ORCID Profile
0000-0002-0116-5427
Current Organisation
University of Queensland
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Zoology | Animal Behaviour | Animal Structure and Function | Physiology | Zoology not elsewhere classified | Population Ecology | Comparative Physiology | Urban And Regional Planning | Environmental Science and Management | Ecology And Evolution Not Elsewhere Classified | Comparative Physiology | Sociobiology And Behavioural Ecology | Wildlife And Habitat Management | Conservation | Ecological Physiology
Expanding Knowledge in the Biological Sciences | Aboriginal and Torres Strait Islander Education | Flora, Fauna and Biodiversity at Regional or Larger Scales | Ecosystem Adaptation to Climate Change | Land and water management | Other | Integrated (ecosystem) assessment and management | Biological sciences |
Publisher: Springer Science and Business Media LLC
Date: 30-03-2000
Abstract: Among hibians, the ability to compensate for the effects of temperature on the locomotor system by thermal acclimation has only been reported in larvae of a single species of anuran. All other analyses have examined predominantly terrestrial adult life stages of hibians and found no evidence of thermal acclimatory capacity. We examined the ability of both tadpoles and adults of the fully aquatic hibian Xenopus laevis to acclimate their locomotor system to different temperatures. Tadpoles were acclimated to either 12 degrees C or 30 degrees C for 4 weeks and their burst swimming performance was assessed at four temperatures between 5 degrees C and 30 degrees C. Adult X. laevis were acclimated to either 10 degrees C or 25 degrees C for 6 weeks and their burst swimming performance and isolated muscle performance was determined at six temperatures between 5 degrees C and 30 degrees C. Maximum swimming performance of cold-acclimated X. laevis tadpoles was greater at cool temperatures and lower at the highest temperature in comparison with the warm-acclimated animals. At the test temperature of 12 degrees C, maximum swimming velocity of tadpoles acclimated to 12 degrees C was 38% higher than the 30 degrees C-acclimation group, while at 30 degrees C, maximum swimming velocity of the 30 degrees C-acclimation group was 41% faster than the 12 degrees C-acclimation group. Maximum swimming performance of adult X. laevis acclimated to 10 degrees C was also higher at the lower temperatures than the 25 degrees C acclimated animals, but there was no difference between the treatment groups at higher temperatures. When tested at 10 degrees C, maximum swimming velocity of the 10 degrees C-acclimation group was 67% faster than the 25 degrees C group. Isolated gastrocnemius muscle fibres from adult X. laevis acclimated to 10 degrees C produced higher relative tetanic tensions and decreased relaxation times at 10 degrees C in comparison with animals acclimated to 25 degrees C. This is only the second species of hibian, and the first adult life stage, reported to have the capacity to thermally acclimate locomotor performance.
Publisher: Elsevier BV
Date: 04-2012
Publisher: Wiley
Date: 04-01-2010
Publisher: Springer Science and Business Media LLC
Date: 24-05-2013
Publisher: Wiley
Date: 02-09-2012
Publisher: The Company of Biologists
Date: 09-2009
DOI: 10.1242/JEB.031310
Abstract: The reasons why many insects breathe discontinuously at rest are poorly understood and hotly debated. Three adaptive hypotheses attempt to explain the significance of these discontinuous gas exchange cycles (DGCs), whether it be to save water, to facilitate gas exchange in underground environments or to limit oxidative damage. Comparative studies favour the water saving hypothesis and mechanistic studies are equivocal but no study has examined the acclimation responses of adult insects chronically exposed to a range of respiratory environments. The present research is the first manipulative study of such chronic exposure to take a strong-inference approach to evaluating the competing hypotheses according to the explicit predictions stemming from them. Adult cockroaches (Nauphoeta cinerea) were chronically exposed to various treatments of different respiratory gas compositions (O2,CO2 and humidity) and the DGC responses were interpreted in light of the a priori predictions stemming from the competing hypotheses. Rates of mass loss during respirometry were also measured for animals acclimated to a range of humidity conditions. The results refute the hypotheses of oxidative damage and underground gas exchange, and provide evidence supporting the hypothesis that DGCs serve to reduce respiratory water loss: cockroaches exposed to low humidity conditions exchange respiratory gases for shorter durations during each DGC and showed lower rates of body mass loss during respirometry than cockroaches exposed to high humidity conditions.
Publisher: Wiley
Date: 04-2005
Publisher: Wiley
Date: 21-09-2012
Publisher: CSIRO Publishing
Date: 09-04-2021
DOI: 10.1071/WR20032
Abstract: Abstract Context Understanding what constitutes high-quality habitat for threatened species is critical for conservation management planning. The endangered northern quoll (Dasyurus hallucatus) has experienced an uneven range contraction among habitat types. Once common across multiple habitats of northern mainland Australia, declining populations have now contracted to rocky escarpments. Aim The island refuge of Groote Eylandt, Northern Territory, Australia, has not experienced the declines as seen on mainland Australia. Here, northern quolls persist in both rocky escarpment and savanna woodland, which provides a rare opportunity to investigate the habitat quality of rocky escarpments and savanna woodland for the northern quoll. Methods Northern quolls (n = 111) were trapped in both rocky escarpment (n = 61) and savanna woodland (n = 50) habitats before the breeding season (May). We conducted body condition assessment, scat analysis, and measured trophic niche breadth of in iduals occupying each habitat type. Key results Female quolls occupying rocky escarpments exhibited a lower body condition than did quolls occupying savanna woodland. Quolls from rocky escarpments consumed a significantly higher proportion of mammals and fed within a narrower dietary niche than did those occupying savanna woodland. Conclusions Quolls had adapted to the dietary resources available within each habitat type, suggesting that the lack of quolls in savanna woodland on the mainland is due to factors other than availability of dietary resources. Implications Groote Eylandt is of critical conservation significance, where high numbers of northern quolls exist in both rocky escarpment and savanna woodland habitats. For population viability on the mainland, managing threats such as feral predators and inappropriate fire regimes in savanna woodland, particularly those surrounding rocky escarpment, should be prioritised.
Publisher: Elsevier BV
Date: 2003
Publisher: The Company of Biologists
Date: 2019
DOI: 10.1242/JEB.189654
Abstract: Characterisation of an organism's performance in different habitats provides insight into the conditions that allow it to survive and reproduce. In recent years, Northern quolls (Dasyurus hallucatus)—a medium-sized semi-arboreal marsupial native to northern Australia—have undergone significant population declines within open forest, woodland and riparian habitats, but less so in rocky areas. To help understand this decline, we quantified the biomechanical performance of wild Northern quolls as they ran up inclined narrow (13 mm pole) and inclined wide (90 mm platform) substrates. We predicted that quolls may possess biomechanical adaptations to increase stability on narrow surfaces, which are more common in rocky habitats. Our results display that quolls have some biomechanical characteristics consistent with a stability advantage on narrow surfaces. This includes the coupled use of limb pairs, as indicated via a decrease in footfall time, and an ability to produce corrective torques to counteract the toppling moments commonly encountered during gait on narrow surfaces. However, speed was constrained on narrow surfaces, and quolls did not adopt diagonal sequence gaits unlike true arboreal specialists such as primates. In comparison with key predators, such as cats and dogs, Northern quolls appear inferior in terrestrial environments but have a stability advantage at higher speeds on narrow supports. This may partially explain the heterogenous declines in Northern quoll populations among various habitats on mainland Australia.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/AM18031
Abstract: Habitat loss and fragmentation threaten the survival of koalas in Queensland. In rural landscapes, remaining koala habitat is often in the form of scattered paddock trees, patches of vegetation and roadside vegetation. The aims of this study were to (1) quantify the use of these three habitat types (2) determine whether there is an increased use of scattered trees during the breeding season and (3) describe the movement characteristics (daily step-length and turning angle) of koalas in different habitat types. To do this, koalas were caught and fitted with global positioning system (GPS) loggers that recorded their daily locations. We found koalas utilised all three habitat types in both breeding and non-breeding seasons, but roadside vegetation and scattered trees were utilised significantly more than expected based on their availability within the landscape. We found no significant difference in step-length or turning angles in scattered trees compared with patches of vegetation. We conclude that scattered trees are a critical element of habitat in this rural landscape. This work provides evidence that retaining or planting scattered trees within the rural landscape would likely complement or possibly enhance the conservation value of rural landscapes for koalas.
Publisher: Wiley
Date: 12-10-2020
Publisher: The Company of Biologists
Date: 2020
DOI: 10.1242/JEB.218503
Abstract: Introduced predators combined with habitat loss and modification are threatening bio ersity worldwide, particularly the ‘critical weight range’ (CWR) mammals of Australia. In order to mitigate the impacts of invasive predators on native species in different landscapes, we must understand how the prey's morphology and performance determine their survival. Here we evaluate how phenotypic traits related to escape performance predict the probability of survival for an endangered CWR mammal, the northern quoll (Dasyurus hallucatus). We measured mass, body size, body shape, body condition, and age, as well as maximum sprint speed, acceleration, and agility of female quolls over two consecutive years. Those with higher body condition and agility around a 135° corner were more likely to survive their first 21 months of life but were not more likely to survive after this period. No other morphological or performance traits affected survival. Heavier second-year in iduals were more agile than first-years but second-years experienced higher mortality rates throughout the year. Females with higher body condition and agility around a 135° corner tended to have shorter limbs and feet but larger heads. Our findings suggest that higher body condition and agility are advantageous for survival in female northern quolls. These results can be used to develop predictive models of predator-prey interactions based on performance capacities and how performance is affected by habitat, aiding conservation efforts to predict and manage the impacts of introduced predators on native species.
Publisher: Elsevier BV
Date: 12-2004
Publisher: The Royal Society
Date: 20-02-2007
Abstract: The reproductive behaviour of the sexually coercive male eastern mosquitofish ( Gambusia holbrooki ) offers an excellent model system for testing the benefits of reversible thermal acclimation responses to mating success. We acclimated male mosquitofish to either 18 or 30°C (14 h light : 10 h dark) for six weeks and tested their ability to obtain coercive copulations in the presence and the absence of male–male competition. Based on the beneficial acclimation hypothesis, we predicted for both sets of experiments that 18°C acclimated males would outperform 30°C acclimated males when tested at 18°C, and vice versa when tested at 30°C. We found that copulation success was greater for acclimated than non-acclimated males at both temperatures when in idual males were tested without competing males. In contrast, when males from the different acclimation treatments were competed against each other for copulations with a single female, the 30°C acclimated males were more aggressive and obtained a greater number of copulations at both test temperatures. Thus, we found a clear benefit for acclimation when fish were tested in a non-competitive environment, but acclimation to cool temperatures was associated with a decrease in aggressive behaviour that reduced mating performance at both test temperatures in a competitive environment. In contrast with the long-held assumption that reversible plasticity is beneficial, the adaptive significance of reversible physiological plasticity is affected by a variety of other ecological factors and is more complex than previously suggested.
Publisher: The Company of Biologists
Date: 2018
DOI: 10.1242/JEB.172544
Abstract: Movement speed can underpin an animal's probability of success in ecological tasks. Prey often use agility to outmanoeuvre predators, however faster speeds increase inertia and reduce agility. Agility is also constrained by grip, as the foot must have sufficient friction with the ground to apply the forces required for turning. Consequently, ground surface should affect optimum turning speed. We tested the speed-agility trade-off in buff-footed antechinus (Antechinus mysticus) on two different surfaces. Antechinus used slower turning speeds over smaller turning radii on both surfaces, as predicted by the speed-agility trade-off. Slipping was 64% more likely on the low-friction surface, and had a higher probability of occurring the faster the antechinus were running before the turn. However, antechinus compensated for differences in surface friction by using slower pre-turn speeds as their amount of experience on the low-friction surface increased, which consequently reduced their probability of slipping. Conversely, on the high-friction surface, antechinus used faster pre-turn speeds in later trials, which had no effect on their probability of slipping. Overall, antechinus used larger turning radii (0.733 ± 0.062 vs 0.576 ± 0.051 m) and slower pre-turn (1.595 ± 0.058 vs 2.174 ± 0.050 ms-1) and turning speeds (1.649 ± 0.061 vs 2.01 ± 0.054 ms-1) on the low-friction surface. Our results demonstrate the interactive effect of surface friction and the speed-agility trade-off on speed choice. To predict wild animals’ movement speeds, future studies should examine the interactions between biomechanical trade-offs and terrain, and quantify the costs of motor mistakes in different ecological activities.
Publisher: Elsevier BV
Date: 05-2003
Publisher: Elsevier BV
Date: 12-2005
Publisher: Springer Science and Business Media LLC
Date: 19-02-2018
DOI: 10.1007/S00360-018-1149-2
Abstract: Studies of sexual selection primarily focus on morphological traits such as body size and secondary trait dimorphism, with less attention been given to the functional differences between the sexes and even more so their thermal performance capacities. Each sex may benefit from possessing different thermal performance capacities that would allow them to maximise their fitness relative to their different reproductive roles especially when performances are closely related to reproductive success. Here, we examine sexual ergence in thermal sensitivities of performance across three populations of the Asian house gecko (Hemidactylus frenatus) over an extensive latitudinal cline. Using analyses of the thermal sensitivity of routine activity, bite force and sprint speed, we explored whether: (i) males and females differed in their optimal temperatures for performance, (ii) the sexes differed in their thermal sensitivities of performance, and (iii) the degree of sexual ergence in thermal sensitivity varied among the populations. Because male H. frenatus are highly aggressive and frequently engage in combat to gain territories and mating opportunities, we expected males would be active over a wider range of temperatures than females and this would favour broad thermal sensitivity curves for males. In addition, we expected a greater ergence between the sexes in thermal sensitivities for the temperate populations that experience greater daily and seasonal thermal variation. We found that males were more active, and had greater bite forces and faster sprint speeds than females, independent of body size. In addition, we found differences between the sexes in thermal sensitivities for the tropical population female H. frenatus were less active and possessed lower sprint speeds at higher temperatures than males. Although H. frenatus from the most variable thermal environments also displayed the broadest thermal performance range, it was the more stable tropical population that exhibited the greatest ergence between the sexes in thermal sensitivity of performance. The ergence in thermal physiology that we detected between the sexes of H. frenatus is consistent with the idea that males will derive mating and territorial advantages for maintaining function over a broader range of temperatures.
Publisher: Wiley
Date: 26-03-2012
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.ENVPOL.2018.03.087
Abstract: Neuromotor deficits are an important sign of manganese (Mn) toxicity in humans and laboratory animals. However, the impacts of Mn exposure on the motor function of wild animals remains largely unknown. Here, we assessed the impact of chronic exposure to Mn from active mining operations on Groote Eylandt, Australia on the motor function of the semi-arboreal northern quoll (Dasyurus hallucatus), an endangered species. The three motor tests conducted-maximum sprint speed on a straight run, manoeuvrability around a corner, and motor control on a balance beam-showed that elevated Mn body burden did not diminish performance of these traits. However, quolls with higher Mn body burden approached a corner at a significantly narrower range of speeds, due to a significantly lower maximum approach speed. Slower speeds approaching a turn may reduce success at catching prey and avoiding predators. Given that maximum sprint speed on a straight run was not affected by Mn body burden, but maximum speed entering a corner was, slower speeds approaching a turn may reflect compensation for otherwise impaired performance in the turn.
Publisher: MDPI AG
Date: 29-07-2018
Abstract: To succeed at a sport, athletes must manage the biomechanical trade-offs that constrain their performance. Here, we investigate a previously unknown trade-off in soccer: how the speed of a kick makes the outcome more predictable to an opponent. For this analysis, we focused on penalty kicks to build on previous models of factors that influence scoring. More than 700 participants completed an online survey, watching videos of penalty shots from the perspective of a goalkeeper. Participants (ranging in soccer playing experience from never played to professional) watched 60 penalty kicks, each of which was occluded at a particular moment (−0.4 s to 0.0 s) before the kicker contacted the ball. For each kick, participants had to predict shot direction toward the goal (left or right). As expected, predictions became more accurate as time of occlusion approached ball contact. However, the effect of occlusion was more pronounced when players kicked with the side of the foot than when they kicked with the top of the foot (instep). For side-foot kicks, the direction of shots was predicted more accurately for faster kicks, especially when a large portion of the kicker’s approach was presented. Given the trade-off between kicking speed and directional predictability, a penalty kicker might benefit from kicking below their maximal speed.
Publisher: The Royal Society
Date: 14-03-2012
Abstract: Animals commonly use their limbs as signals and weapons during territorial aggression. Asymmetries of limb performance that do not relate to asymmetries of limb size (cryptic asymmetry) could substantially affect disputes, but this phenomenon has not been considered beyond primates. We investigated cryptic asymmetry in male crayfish ( Cherax dispar ), which commonly use unreliable signals of strength during aggression. Although the strength of a chela can vary by an order of magnitude for a given size, we found repeatable asymmetries of strength that were only weakly related to asymmetries of size. Size-adjusted strength of chelae and the asymmetry of strength between chelae were highly repeatable between environmental conditions, suggesting that asymmetries of strength stemmed from variation in capacity rather than motivation. Cryptic asymmetry adds another dimension of uncertainty during conflict between animals, which could influence the evolution of unreliable signals and morphological asymmetry.
Publisher: Wiley
Date: 13-04-2020
Publisher: Wiley
Date: 28-06-2013
DOI: 10.1111/IJN.12121
Abstract: The aim of this review is to explore the literature relating to the delivery of cervical screening by practice nurses (PNs) in the United Kingdom and Australia. Research relating to PNs began in earnest approximately 15 years ago in the UK context, and more recently, c.2005, in Australia. Although there is scant literature devoted specifically to the role of PNs in cervical screening, literature relating to the role of PNs provides evidence of the extent to which PNs in the United Kingdom and Australia are involved in the provision of cervical screening services. Findings from this review indicate that the role of PNs in the provision of cervical screening differs substantially between the United Kingdom and Australia. PNs in the United Kingdom provide a high percentage of cervical screening services, whereas in Australia general practitioners provide around 80% of all cervical smears, which account for only 0.6% of all procedures undertaken by PNs. Employment and funding models and inadequate multidisciplinary collaboration are contributing to the underutilization of PNs in Australia.
Publisher: JSTOR
Date: 03-1998
DOI: 10.2307/1565493
Publisher: Wiley
Date: 03-12-0009
DOI: 10.1111/SMS.13276
Abstract: During a soccer penalty, the shooter's strategy and the goalkeeper's strategy interact to determine the outcome. However, most models of penalty success overlook its interactive nature. Here, we quantified aspects of shooter and goalkeeper strategies that interact to influence the outcome of soccer penalties-namely, how the speed of the shot affects the goalkeeper's leave time or shot-blocking success, and the effectiveness of deceptive strategies. We competed 7 goalkeepers and 17 shooters in a series of penalty shoot-out competitions with a total of 1278 shots taken. Each player was free to use any strategy within the rules of a penalty shot, and game-like pressure was created via monetary incentive for goal-scoring (or blocking). We found that faster shots lead to earlier leave times and were less likely blocked by goalkeepers, and-unlike most previous studies-that deceptive shooting strategies did not decrease the likelihood goalkeepers moved in the correct direction. To help identify optimal strategies for shooters and goalkeepers, we generated distributions and mathematical functions sport scientists can use to develop more comprehensive models of penalty success.
Publisher: Wiley
Date: 02-2008
Publisher: The Royal Society
Date: 05-2007
Abstract: The mating system of eastern mosquito fish ( Gambusia holbrooki ) is dominated by male sexual coercion, where all matings are forced and females never appear to cooperate and actively avoid all attempts. Previous research has shown that male G. holbrooki offer a model system for examining the benefits of reversible thermal acclimation for reproductive success, but examining the benefits to female avoidance behaviour has been difficult. In this study, we examined the ability of non-male-deprived female G. holbrooki to avoid forced–coercive matings following acclimation to either 18 or 30°C for six weeks (12 h light : 12 h dark photoperiod). Thermal acclimation of burst and sustained swimming performance was also assessed, as these traits are likely to underlie their ability to avoid forced matings. There was no influence of thermal acclimation on the burst swimming performance of female G. holbrooki over the range 18–30°C however, sustained swimming performance was significantly lower in the warm- than the cool-acclimation group. For mating behaviour, we tested the hypothesis that acclimation would enhance the ability of female G. holbrooki to avoid forced matings at their host acclimation temperature relative to females acclimated to another environment. However, our hypothesis was not supported. The rate of copulations was almost three times greater for females acclimated to 30°C than 18°C when tested at 30°C, indicating that they possess the ability to alter their avoidance behaviour to ‘allow’ more copulations in some environments. Coupled with previous studies, female G. holbrooki appear to have greater control on the outcome of coercive mating attempts than previously considered and can alter their propensity to receive forced matings following thermal acclimation. The significance of this change in female mating-avoidance behaviours with thermal acclimation remains to be explored.
Publisher: Elsevier BV
Date: 04-2015
Publisher: Wiley
Date: 14-05-2012
Publisher: Wiley
Date: 18-08-2020
DOI: 10.1002/ECE3.6593
Publisher: Wiley
Date: 30-11-2018
DOI: 10.1111/CONL.12427
Publisher: Springer Science and Business Media LLC
Date: 24-09-1999
Abstract: Previous analyses of thermal acclimation of locomotor performance in hibians have only examined the adult life history stage and indicate that the locomotor system is unable to undergo acclimatory changes to temperature. In this study, we examined the ability of tadpoles of the striped marsh frog (Limnodynastes peronii) to acclimate their locomotor system by exposing them to either 10 degrees C or 24 degrees C for 6 weeks and testing their burst swimming performance at 10, 24, and 34 degrees C. At the test temperature of 10 degrees C, maximum velocity (Umax) of the 10 degrees C-acclimated tadpoles was 47% greater and maximum acceleration (Amax) 53% greater than the 24 degrees C-acclimated animals. At 24 degrees C, Umax was 16% greater in the 10 degrees C-acclimation group, while there was no significant difference in Amax or the time taken to reach Umax (T-Umax). At 34 degrees C, there was no difference between the acclimation groups in either Umax or Amax, however T-Umax was 36% faster in the 24 degrees C-acclimation group. This is the first study to report an hibian (larva or adult) possessing the capacity to compensate for cool temperatures by thermal acclimation of locomotor performance. To determine whether acclimation period affected the magnitude of the acclimatory response, we also acclimated tadpoles of L. peronii to 10 degrees C for 8 months and compared their swimming performance with tadpoles acclimated to 10 degrees C for 6 weeks. At the test temperatures of 24 degrees C and 34 degrees C, Umax and Amax were significantly slower in the tadpoles acclimated to 10 degrees C for 8 months. At 10 degrees C, T-Umax was 40% faster in the 8-month group, while there were no differences in either Umax or Amax. Although locomotor performance was enhanced at 10 degrees C by a longer acclimation period, this was at the expense of performance at higher temperatures.
Publisher: Wiley
Date: 09-05-2018
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/AM12023
Abstract: In principle, conservation planning relies on long-term data in reality, conservation decisions are apt to be based upon limited data and short-range goals. For the koala (Phascolarctos cinereus), frequently reliance is made on the assumption that indirect signs can be used to indicate behavioural preferences, such as diet choice. We examined the relationship between the use of trees by koalas and the presence of scats beneath those trees. Tree use was associated with scat presence on 49% of occasions when koalas were radio-tracked in both central Queensland (n = 10 koalas) and south-east Queensland (n = 5 koalas), increasing to 77% of occasions when trees were rechecked the following day. Koala densities were correlated with scat abundance at sites with koala density between ~0.2 and 0.6 koalas per hectare. Our results confirm that scat searches are imprecise indicators of tree use by koalas, but demonstrate that these searches can be used, with caveats, to estimate koala population densities. We discuss how errors in estimating or applying predictive model parameters can bias estimates of occupancy and show how a failure to validate adequately the assumptions used in modelling and mapping can undermine the power of the products to direct rational conservation and management efforts.
Publisher: Public Library of Science (PLoS)
Date: 21-01-2022
DOI: 10.1371/JOURNAL.PONE.0261613
Abstract: Completing the genotype-to-phenotype map requires rigorous measurement of the entire multivariate organismal phenotype. However, phenotyping on a large scale is not feasible for many kinds of traits, resulting in missing data that can also cause problems for comparative analyses and the assessment of evolutionary trends across species. Measuring the multivariate performance phenotype is especially logistically challenging, and our ability to predict several performance traits from a given morphology is consequently poor. We developed a machine learning model to accurately estimate multivariate performance data from morphology alone by training it on a dataset containing performance and morphology data from 68 lizard species. Our final, stacked model predicts missing performance data accurately at the level of the in idual from simple morphological measures. This model performed exceptionally well, even for performance traits that were missing values for % of the s led in iduals. Furthermore, incorporating phylogeny did not improve model fit, indicating that the phenotypic data alone preserved sufficient information to predict the performance based on morphological information. This approach can both significantly increase our understanding of performance evolution and act as a bridge to incorporate performance into future work on phenomics.
Publisher: University of Chicago Press
Date: 02-09-2016
DOI: 10.1086/687588
Abstract: Environmental temperature has profound effects on animal physiology, ecology, and evolution. Glucocorticoid (GC) hormones, through effects on phenotypic performance and life history, provide fundamental vertebrate physiological adaptations to environmental variation, yet we lack a comprehensive understanding of how temperature influences GC regulation in vertebrates. Using field studies and meta- and comparative phylogenetic analyses, we investigated how acute change and broadscale variation in temperature correlated with baseline and stress-induced GC levels. Glucocorticoid levels were found to be temperature and taxon dependent, but generally, vertebrates exhibited strong positive correlations with acute changes in temperature. Furthermore, reptile baseline, bird baseline, and capture stress-induced GC levels to some extent covaried with broadscale environmental temperature. Thus, vertebrate GC function appears clearly thermally influenced. However, we caution that lack of detailed knowledge of thermal plasticity, heritability, and the basis for strong phylogenetic signal in GC responses limits our current understanding of the role of GC hormones in species' responses to current and future climate variation.
Publisher: The Company of Biologists
Date: 15-04-2010
DOI: 10.1242/JEB.028472
Abstract: The low pH of naturally acidic aquatic environments is the result of soft-water with low buffering capacity and high concentrations of natural organic acids. Our current understanding of the influence of pH on aquatic organisms is largely limited to laboratory studies conducted under controlled conditions with little incorporation of these organic acids. Recent studies suggest natural organic acids may influence the physiology of aquatic species independent of low pH. We examined the effects of pH and varying concentrations of natural wallum water, which is high in organic acids on the hatching success, growth and locomotor performance of larval striped marsh frogs (Limnodynastes peronii). Based on previous studies, we predicted that the detrimental effects of low pH would be further exacerbated by higher concentrations of naturally occurring organic acids (high concentrations of wallum water). In artificial soft-water, embryos experienced both reduced growth and reduced survival when exposed to low pH. However, greater concentrations of natural organic acids did not exacerbate these effects of low pH on growth and development. Instead, we found some evidence that the natural organic acids within wallum water improved growth and swimming performance across all pH treatments. Using path analyses to investigate the effects of pH and natural organic acid concentration on burst swimming performance, we found performance was directly affected by both body length and organic acid concentration. Our data further highlight our limited understanding of the importance of natural organic acids for aquatic organisms and the need to incorporate greater ecological relevance into these studies.
Publisher: The Company of Biologists
Date: 03-2004
DOI: 10.1242/JEB.00870
Abstract: Tropidurid lizards have colonized a variety of Brazilian open environments without remarkable morphological variation, despite ecological and structural differences among habitats used. This study focuses on two Tropidurussister-species that, despite systematic proximity and similar morphology,exhibit great ecological ergence and a third ecologically generalist congeneric species providing an outgroup comparison. We quantified jumping capacity and sprint speed of each species on sand and rock to test whether ecological ergence was also accompanied by differences in locomotor performance. Relevant physiological traits possibly associated with locomotor performance – metabolic scopes and fiber type composition, power output and activity of the enzymes citrate synthase, pyruvate kinase and lactate dehydrogenase of the iliofibularis muscle – were also compared among the three Tropidurus species. We found that the two sister-species exhibited remarkable differences in jumping performance, while Tropidurus oreadicus, the more distantly related species, exhibited intermediate values. Tropidurus psamonastes, a species endemic to sand dunes,exhibited high absolute sprint speeds on sand, jumped rarely and possessed a high proportion of glycolytic fibers and low activity of citrate synthase. The sister-species Tropidurus itambere, endemic to rocky outcrops,performed a large number of jumps and achieved lower absolute sprint speed than T. psamonastes. This study provides evidence of rapid ergence of locomotor parameters between sister-species that use different substrates,which is only partially explained by variation in physiological parameters of the iliofibularis muscle.
Publisher: Wiley
Date: 02-09-2020
DOI: 10.1111/SMS.13782
Publisher: Springer Science and Business Media LLC
Date: 17-10-2016
DOI: 10.1007/S00360-015-0938-0
Abstract: Many of the far-reaching impacts of climate change on ecosystem function will be due to alterations in species interactions. However, our understanding of the effects of temperature on the dynamics of interactions between species is largely inadequate. Inducible defences persist in prey populations because defensive traits increase survival in the presence of predators but are costly when they are absent. Large-scale changes in the thermal climate are likely to alter the costs or benefits of these defences for ectotherms, whose physiological processes are driven by environmental temperature. A shift in costs of defensive traits would affect not only predator-prey interactions, but also the strength of selection for inducible defences in natural populations. We investigate the effect of temperature on the costs of behavioural defences in larvae of the marine toad, Rhinella marinus. Larvae were reared in the presence or absence of predator cues at both 25 and 30 °C. When exposed to predation cues, larvae reduced activity and spent less time feeding. Exposure to predation cues also reduced metabolic rate, presumably as a by-product of reducing activity levels. Larvae exposed to predation cues also grew more slowly, were smaller at metamorphosis and were poorer jumpers after metamorphosis--three traits associated with fitness in post-metamorphic anurans. We found that the costs of behavioural defences, in terms of larval growth, post-metamorphic size and jumping performance, were exacerbated at cooler temperatures. The thermal sensitivity of costs associated with defensive traits may explain geographic variation in plasticity of defensive traits in other species and suggests that changes in environmental temperature associated with climate change may affect predator-prey interactions in subtle ways not previously considered.
Publisher: Public Library of Science (PLoS)
Date: 16-11-2016
Publisher: The Company of Biologists
Date: 2014
DOI: 10.1242/JEB.099390
Abstract: To reduce the potential costs of combat, animals may rely upon signals to resolve territorial disputes. Signals also provide a means for in iduals to appear better than they actually are, deceiving opponents and gaining access to resources that would otherwise be unattainable. However, other than resource gains, incentives for dishonest signalling remain unexplored. In this study, we tested the idea that unreliable signallers pay lower metabolic costs for their signals, and that energetic savings could represent an incentive for cheating. We focused on two-toned fiddler crabs (Uca vomeris), a species that frequently uses their enlarged claws as signals of dominance to opponents. Previously, we found that regenerated Uca vomeris claws are often large but weak (i.e. unreliable). Here, we found that the original claws of male Uca vomeris consumed 43% more oxygen than weaker, regenerated claws suggesting that muscle quantity drives variation in metabolic costs. Therefore, it seems that metabolic savings could provide a powerful incentive for dishonesty within fiddler crabs.
Publisher: The Company of Biologists
Date: 02-2015
DOI: 10.1242/JEB.111682
Abstract: Movement speed is fundamental to all animal behaviour, yet no general framework exists for understanding why animals move at the speeds they do. Even during fitness-defining behaviours like running away from predators, an animal should select a speed that balances the benefits of high speed against the increased probability of mistakes. In this study, we explored this idea by quantifying trade-offs between speed, manoeuvrability and motor control in wild northern quolls (Dasyurus hallucatus) – a medium-sized carnivorous marsupial native to northern Australia. First, we quantified how running speed affected the probability of crashes when rounding corners of 45, 90 and 135 deg. We found that the faster an in idual approached a turn, the higher the probability that they would crash, and these risks were greater when negotiating tighter turns. To avoid crashes, quolls modulated their running speed when they moved through turns of varying angles. Average speed for quolls when sprinting along a straight path was around 4.5 m s−1 but this decreased linearly to speeds of around 1.5 m s−1 when running through 135 deg turns. Finally, we explored how an in idual's morphology affects their manoeuvrability. We found that in iduals with larger relative foot sizes were more manoeuvrable than in iduals with smaller relative foot sizes. Thus, movement speed, even during extreme situations like escaping predation, should be based on a compromise between high speed, manoeuvrability and motor control. We advocate that optimal – rather than maximal – performance capabilities underlie fitness-defining behaviours such as escaping predators and capturing prey.
Publisher: University of Chicago Press
Date: 07-2013
DOI: 10.1086/671191
Abstract: The locomotor capacity of hibians depends strongly on temperature and hydration. Understanding the potential interactions between these variables remains an important challenge because temperature and water availability covary strongly in natural environments. We explored the effects of temperature and hydration on the hopping speeds of Rhinella granulosa, a small toad from the semiarid Caatinga and the Atlantic Rain Forest in Brazil. We asked whether thermal and hydric states interact to determine performance and whether toads from the Caatinga differ from their conspecifics from the Atlantic Forest. Both dehydration and cooling impaired hopping speed, but effects were independent of one another. In comparison to performances of other anurans, the performance of R. granulosa was far less sensitive to dehydration. Consequently, dehydrated members of this species may be able to sustain performance through high body temperatures, which agrees with the exceptional heat tolerance of this species. Surprisingly, toads from both the Caatinga and the Atlantic Forest were relatively insensitive to dehydration. This observation suggests that migration or gene flow between toads from the forest and those from a drier region occurred or that toads from a dry region colonized the forest secondarily.
Publisher: The Company of Biologists
Date: 15-06-2004
DOI: 10.1242/JEB.01041
Abstract: Amphisbaenians are legless reptiles that differ significantly from other vertebrate lineages. Most species dig underground galleries of similar diameter to that of the animal. We studied the muscle physiology and morphological attributes of digging effort in the Brazilian hisbaenid Leposternon microcephalum (Squamata Amphisbaenia), which burrows by compressing soil against the upper wall of the tunnel by means of upward strokes of the head. The in iduals tested (& g) exerted forces on the soil of up to 24 N. These forces were possible because the fibres of the longissimus dorsi, the main muscle associated with burrowing, are highly pennated, thus increasing effective muscle cross-sectional area. The muscle is characterized by a metabolic transition along its length: proximal, medial and distal fibres are fast contracting and moderately oxidative, but fibres closer to the head are richer in citrate synthase and more aerobic in nature. Distal fibres, then, might be active mainly at the final step of the compression stroke, which requires more power. For animals greater than a given diameter,the work required to compress soil increases exponentially with body diameter. Leposternon microcephalum, and probably some other highly specialized hisbaenids, are most likely constrained to small diameters and can increase muscle mass and effective muscle cross-sectional area by increasing body length, not body diameter.
Publisher: The Company of Biologists
Date: 15-12-2006
DOI: 10.1242/JEB.02531
Abstract: Few studies have examined the adaptive significance of reversible acclimation responses. The aerobic performance and mating behaviour of the sexually coercive male eastern mosquito fish (Gambusia holbrooki)offers an excellent model system for testing the benefits of reversible acclimation responses to mating success. We exposed male mosquito fish to normoxic or hypoxic conditions for 4 weeks and tested their maximum sustained swimming performance and their ability to obtain coercive matings under both normoxic and hypoxic conditions. We predicted that hypoxia-acclimated males would possess greater swimming and mating performance in hypoxic conditions than normoxic-acclimated males, and vice versa when tested in normoxia. Supporting our predictions, we found the sustained swimming performance of male mosquito fish was greater in a hypoxic environment following long-term exposure to low partial pressures of oxygen. However, the benefits of acclimation responses to mating performance were dependent on whether they were tested in the presence or absence of male-male competition. In a non-competitive environment, male mosquito fish acclimated to hypoxic conditions spent a greater amount of time following females and obtained more copulations than normoxic-acclimated males when tested in low partial pressures of oxygen. When males were competed against each other for copulations, we found no influence of long-term exposure to different partial pressures of oxygen on mating behaviour. Thus, despite improvements in the aerobic capacity of male mosquito fish following long-term acclimation to hypoxic conditions, these benefits did not always manifest themselves in improved mating performance. This study represents one of the first experimental tests of the benefits of reversible acclimation responses, and indicates that the ecological significance of physiological plasticity may be more complicated than previously imagined.
Publisher: Wiley
Date: 12-10-2018
DOI: 10.1111/EVO.13617
Abstract: Many exaggerated morphological traits evolve under sexual selection. However, the optimal level of exaggeration is dictated by a trade-off between natural and sexual selection, representing a balance between its benefits and associated costs. Male fiddler crabs wave an enlarged major claw during behavioural displays that eliminates the need for direct combat, and determines courtship outcomes. The outcomes of these displays often depend on claw size, exposing males to selection for larger claws to improve mating and combat success. Applying phylogenetic comparative methods to 27 fiddler crab species, we examined the evolution of major claw morphologies, leg morphologies, and waving displays to determine whether these traits coevolved to optimise functioning of the exaggerated claw, or to mitigate potential metabolic or locomotor costs. We found legs to be sexually dimorphic, with males having longer legs than females. Legs were also longer in species that waved laterally rather than vertically, in species with larger major claws, and in species whose major claws were relatively elongate. These results suggest that leg morphology has coevolved with claw enlargement to enhance functionality of the major claw during waving displays, in addition to compensating for any negative effects of claw size.
Publisher: Public Library of Science (PLoS)
Date: 28-02-2007
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.JBIOMECH.2022.111208
Abstract: Success in a soccer penalty can be the difference between winning and losing matches. The outcome is determined by a complex interaction between the shooter and goalkeeper, whose performances are constrained by biomechanical trade-offs. To overcome these performance constraints, each player has a range of available strategies. Shooters can kick at different speeds, affecting accuracy, while goalkeepers can move at various times (leave-times), affecting the time available to move and the probability they move in the correct direction. Previous models of penalty success ignore such trade-offs and how they interact to influence the outcome. Here, we present a model that accounts for shooting inaccuracy to predict the probability of success for all shooting strategies, defined as any combination of: shot speed, position where the shooter aims, shooter footedness, and kicking technique (side-foot or instep). To estimate the probability of success each shooting strategy is matched against all possible goalkeeper leave-times, considering the probability each leave-time is chosen. We test the model against an average goalkeeper and a goalkeeper who tends to move later. Against the average goalkeeper, aiming on the ground toward the centre of the goal is optimal however, against a late moving goalkeeper, aiming on the ground to the extremities of the goal is effective, with the optimal target in the horizontal dimension dependent on shot speed, kick technique, and footedness. Coaches could use this model to identify their best penalty takers and each players' optimal shooting strategy against either the average goalkeeper or a specific goalkeeper.
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/WR19052
Abstract: Abstract ContextAustralia has experienced the highest number of mammal extinctions of any continent over the past two centuries. Understanding the demography and spatial requirements of populations before declines occur is fundamental to confirm species trajectory, elucidate causes of decline and develop effective management strategies. AimsWe evaluated the demography and spatial requirements of a northern quoll, Dasyurus hallucatus, population on Groote Eylandt, Northern Territory. Groote Eylandt is considered a refuge for the species because key threatening processes are absent or limited cane toads and introduced ungulates are absent, feral cats are infrequently detected and the fire regime is benign compared with mainland Northern Territory. MethodsWe conducted a 4-year capture–mark–recapture study to monitor growth, reproduction and survival of northern quolls within a 128-ha area, and we evaluated spatial requirements by attaching GPS units to both sexes. To assess the status of the Groote Eylandt population, we compared the demographics with existing data from mainland populations. Key resultsThe average density of northern quolls was 0.33ha−1. However, there was a 58% decline in female density, primarily between 2012 and 2013, corresponding with a decrease in female body mass. Females survived and bred in up to 3 years and adult survival rates did not vary among years, suggesting that juvenile recruitment drives population fluctuations. Male quolls were semelparous, with die-off occurring in the months following breeding. The median female and male home ranges were 15.7ha and 128.6ha respectively, and male ranges increased significantly during breeding, with 1616ha being the largest recorded. ConclusionsThe northern quoll population on Groote Eylandt had a higher density, female survival and reproductive success than has been previously recorded on the mainland. However, a marked decline was recorded corresponding with a decrease in female mass, indicating below-average rainfall as the likely cause. ImplicationsGroote Eylandt remains a refuge for the endangered northern quoll. However, even in the absence of key threatening processes, the population has declined markedly, highlighting the impact of environmental fluctuations. Maintaining the ecological integrity of Groote Eylandt is imperative for population recovery, and managing threats on the mainland over appropriate spatial scales is necessary to increase population resilience.
Publisher: Wiley
Date: 06-11-2006
Publisher: The Royal Society
Date: 10-07-2007
Abstract: The outcomes of agonistic interactions modulate access to resources and thereby affect fitness. Success in agonistic encounters may depend on intrinsic physical and physiological performance, and on social experience. Here we test the hypothesis that previous experience will override physical strength in determining the outcome of fights in the freshwater crayfish Cherax dispar . Between unfamiliar opponents, greater chelae closing force significantly increases the chances of winning. However, even when the chelae of the original winners were disabled, the winners kept on winning against the same opponents after 30 min and 24 h. This winner effect disappeared when previous winners encountered unfamiliar in iduals. Similarly, a previous loss did not affect the outcomes of subsequent encounters with unknown crayfish. We suggest that this prolonged recognition of in iduals and their relative fighting ability is a mechanism that can reduce the number of agonistic encounters experienced by in iduals.
Publisher: The Company of Biologists
Date: 10-2011
DOI: 10.1242/JEB.056754
Abstract: The maintenance of unreliable signals within animal populations remains a highly controversial subject in studies of animal communication. Crustaceans are an ideal group for studying unreliable signals of strength because their chela muscles are cryptically concealed beneath an exoskeleton, making it difficult for competitors to visually assess an opponent's strength. In this study, we examined the importance of social avenues for mediating the possible advantages gained by unreliable signals of strength in crustaceans. To do this, we investigated the factors that determine social dominance and the relative importance of signalling and fighting during aggressive encounters in male and female freshwater crayfish, Cherax destructor. Like other species of crayfish, we expected substantial variation in weapon force for a given weapon size, making the assessment of actual fighting ability of an opponent difficult from signalling alone. In addition, we expected fighting would be used to ensure that in iduals that are weak for their signal (i.e. chela) size would not achieve higher than expected dominance. For both male and female C. destructor, we found large variation in the actual force of their chela for any given weapon size, indicating that it is difficult for competitors to accurately assess an opponent's force on signal size alone. For males, these unreliable signals of strength were controlled socially through increased levels of fighting and a decreased reliance on signalling, thus directly limiting the benefits accrued to in iduals employing high-quality signals (large chelae) with only low resource holding potential. However, in contrast to our predictions, we found that females primarily relied on signalling to settle disputes, resulting in unreliable signals of strength being routinely used to establish dominance. The reliance by females on unreliable signals to determine dominance highlights our poor current understanding of the prevalence and distribution of dishonesty in animal communication.
Publisher: Springer Science and Business Media LLC
Date: 24-05-2019
Publisher: Springer Science and Business Media LLC
Date: 08-06-2004
DOI: 10.1007/S00360-004-0431-7
Abstract: Interin idual analyses of physiological performance represent one of the most powerful tools for identifying functional positive and negative linkages between various performance traits. In this study we investigated functional linkages in the whole-gastrocnemius performance of juvenile Bufo viridis by examining interin idual variation in in vitro muscle performance and muscle fibre-type composition. We used the work-loop technique to investigate the maximum in vitro power output and fatigue resistance of the gastrocnemius muscle during repeated sets of three cycles at the cycle frequency of 5 Hz, simulating an intermittent style of locomotion. We found several significant correlations between different measures of in vitro muscle performance, including a negative correlation between maximum net power output and fatigue resistance of power, indicating functional trade-offs between these performance traits. We also investigated the extent of in idual variation in the proportions of different fibre types, and tested for correlations between in idual variation in muscle fibre-type composition and the previously measured isolated muscle performance. Fast glycolytic fibres represented 84.0 +/- 3.4% of the muscle, while the combined slow oxidative and fast oxidative-glycolytic fibres represented 16 +/- 3.4%. We found no significant correlations between measures of in vitro muscle performance and the proportion of different fibre types in the gastrocnemius muscle. However, despite this lack of correlation between whole-muscle performance and muscle fibre-type composition data, we suggest the functional linkages detected between different measures of in vitro muscular performance have important ecological and evolutionary consequences.
Publisher: Wiley
Date: 27-04-2013
Publisher: The Royal Society
Date: 02-08-2017
Abstract: The mechanistic foundations of performance trade-offs are clear: because body size and shape constrains movement, and muscles vary in strength and fibre type, certain physical traits should act in opposition with others (e.g. sprint versus endurance). Yet performance trade-offs are rarely detected, and traits are often positively correlated. A potential resolution to this conundrum is that within -in idual performance trade-offs can be masked by among -in idual variation in ‘quality’. Although there is a current debate on how to unambiguously define and account for quality, no previous studies have partitioned trait correlations at the within- and among-in idual levels. Here, we evaluate performance trade-offs among and within 1369 elite athletes that performed in a total of 6418 combined-events competitions (decathlon and heptathlon). Controlling for age, experience and wind conditions, we detected strong trade-offs between groups of functionally similar events (throwing versus jumping versus running) occurring at the among-in idual level. We further modelled in idual (co)variation in age-related plasticity of performance and found previously unseen trade-offs in throwing versus running performance that manifest through ageing. Our results verify that human performance is limited by fundamental genetic, environmental and ageing constraints that preclude the simultaneous improvement of performance in multiple dimensions. Identifying these constraints is fundamental to understanding performance trade-offs and predicting the ageing of motor function.
Publisher: University of Chicago Press
Date: 09-2005
DOI: 10.1086/432149
Abstract: Frog jumping is an excellent model system for examining the structural basis of interin idual variation in burst locomotor performance. Some possible factors that affect jump performance, such as total body size, hindlimb length, muscle mass, and muscle mechanical and biochemical properties, were analysed at the interin idual (intraspecies) level in the tree frog Hyla multilineata. The aim of this study was to determine which of these physiological and anatomical variables both vary between in iduals and are correlated with interin idual variation in jump performance. The model produced via stepwise linear regression analysis of absolute data suggested that 62% of the interin idual variation in maximum jump distance could be explained by a combination of interin idual variation in absolute plantaris muscle mass, total hindlimb muscle mass (excluding plantaris muscle), and pyruvate kinase activity. When body length effects were removed, multiple regression indicated that the same independent variables explained 43% of the residual interin idual variation in jump distance. This suggests that in iduals with relatively large jumping muscles and high pyruvate kinase activity for their body size achieved comparatively large maximal jump distances for their body size.
Publisher: The Company of Biologists
Date: 15-03-2009
DOI: 10.1242/JEB.024547
Abstract: Unreliable signals of weapon strength are considered to be problematic for signalling theory and reliable signals are predicted to be the dominant form of signalling among conspecifics in nature. Previous studies have shown that males of the Australian freshwater crayfish (Cherax dispar) routinely use unreliable signals of strength whereas females use reliable signals of weapon strength. In this study, we examined the performance benefits of increased weapon (chela) size for both males and females of C. dispar. In addition, we investigated the possibility of functional trade-offs in weapon size by assessing the relationship between chela size and maximum escape swimming performance. We found males possessed larger and stronger chelae than females and the variance in chela force was greater for males than females. By contrast, females possessed greater absolute and body length-specific escape swimming speeds than males. Swimming speed was also negatively correlated with chela size for males but not females, suggesting that a functional trade-off exists for males only. Decreases in swimming speed with increases in weapon size suggest there could be important fitness costs associated with larger chelae. Larger weaponry of males may then act as a handicap ensuring large chelae are reliable signals of quality.
Publisher: Oxford University Press (OUP)
Date: 22-06-2020
DOI: 10.1093/ICB/ICAA070
Abstract: Prey species often modify their foraging and reproductive behaviors to avoid encounters with predators yet once they are detected, survival depends on out-running, out-maneuvering, or fighting off the predator. Though predation attempts involve at least two in iduals—namely, a predator and its prey—studies of escape performance typically measure a single trait (e.g., sprint speed) in the prey species only. Here, we develop a theoretical model in which the likelihood of escape is determined by the prey animal’s tactics (i.e., path trajectory) and its acceleration, top speed, agility, and deceleration relative to the performance capabilities of a predator. The model shows that acceleration, top speed, and agility are all important determinants of escape performance, and because speed and agility are biomechanically related to size, smaller prey with higher agility should force larger predators to run along curved paths that do not allow them to use their superior speeds. Our simulations provide clear predictions for the path and speed a prey animal should choose when escaping from predators of different sizes (thus, biomechanical constraints) and could be used to explore the dynamics between predators and prey.
Publisher: Wiley
Date: 20-03-2014
DOI: 10.1111/EVO.12375
Abstract: Phenotypic traits are often influenced by dynamic resource allocation trade-offs which, when occurring over the course of in idual lifespan, may manifest as trait aging. Although aging is studied for a variety of traits that are closely tied to reproduction or reproductive effort, the aging of multiple traits related to fitness in other ways are less well understood. We took advantage of almost 30 years of data on human whole-organism performance in the National Basketball Association (USA) to examine trends of aging in performance traits associated with scoring. Given that patterns of aging differ between sexes in other animal species, we also analyzed a smaller dataset on players in the Women's National Basketball Association to test for potential sex differences in the aging of comparable traits. We tested the hypothesis that age-related changes in a specific aspect of overall performance can be compensated for by elevated expression of another, related aspect. Our analyses suggest that the aging of performance traits used in basketball is generally characterized by senescence in males, whereas age-related changes in basketball performance are less evident in females. Our data also indicate a different rate of senescence of different performance traits associated with scoring over a male's lifetime.
Publisher: Public Library of Science (PLoS)
Date: 27-08-2015
Publisher: Wiley
Date: 22-09-2015
DOI: 10.1111/BJSO.12129
Abstract: This study examined whether people can detect deception after the fact if they initially accept someone's behaviour at face value but then learn that they have been duped. Fifty-four groups composed of four to six mutual friends engaged in a group discussion with a financial incentive for arriving at a correct decision. One member of each group was secretly assigned to sabotage the decision. Although none of the participants noticed the deception when it was committed, they showed substantial accuracy in identifying the saboteur once they were told that a deception had occurred. Nevertheless, interrogation did not increase the accuracy of their detection of deception. Participants showed a significant positive relationship between confidence and accuracy. Finally, participants also showed better-than-chance accuracy in their judgments of who believed them during the interrogation and who did not. These results suggest that the detection of deception might often be accomplished using information gained after the fact to reinterpret behaviours that were not initially suspected.
Publisher: Public Library of Science (PLoS)
Date: 05-10-2011
Publisher: American Physiological Society
Date: 02-2004
DOI: 10.1152/JAPPLPHYSIOL.00696.2003
Abstract: The effects of 10 mM (high) and 70 μM (physiologically relevant) caffeine on force, work output, and power output of isolated mouse extensor digitorum longus (EDL) and soleus muscles were investigated in vitro during recovery from fatigue at 35°C. To monitor muscle performance during recovery from fatigue, we regularly subjected the muscle to a series of cyclical work loops. Force, work, and power output during shortening were significantly higher after treatment with 10 mM caffeine, probably as a result of increased Ca 2+ release from the sarcoplasmic reticulum. However, the work required to relengthen the muscle also increased in the presence of 10 mM caffeine. This was due to a slowing of relaxation and an increase in muscle stiffness. The combination of increased work output during shortening and increased work input during lengthening had different effects on the two muscles. Net power output of mouse soleus muscle decreased as a result of 10 mM caffeine exposure, whereas net power output of the EDL muscle showed a transient, significant increase. Treatment with 70 μM caffeine had no significant effect on force, work, or power output of EDL or soleus muscles, suggesting that the plasma concentrations found when caffeine is used to enhance performance in human athletes might not directly affect the contractile performance of fatigued skeletal muscle.
Publisher: Elsevier BV
Date: 09-2006
Publisher: Wiley
Date: 08-09-0009
DOI: 10.1111/J.1420-9101.2011.02227.X
Abstract: Thermal performance curves (TPCs) provide a powerful framework for studying the evolution of continuous reaction norms and for testing hypotheses of thermal adaptation. Although featured heavily in comparative studies, the framework has been comparatively underutilized for quantitative genetic tests of thermal adaptation. We assayed the distribution of genetic (co)variance for TPC (locomotor activity) within and among three natural populations of Drosophila serrata and performed replicated tests of two hypotheses of thermal adaptation--that 'hotter is better' and that a generalist-specialist trade-off underpins the evolution of thermal sensitivity. We detected significant genetic variance within, and ergence among, populations. The 'hotter is better' hypothesis was not supported as the genetic correlations between optimal temperature (T(opt)) and maximum performance (z(max)) were consistently negative. A pattern of variation consistent with a generalist-specialist trade-off was detected within populations and ergence among populations indicated that performance curves were narrower and had higher optimal temperatures in the warmer, but less variable tropical population.
Publisher: University of Chicago Press
Date: 08-2007
DOI: 10.1086/519399
Abstract: Many animals resolve disputes without combat by displaying signals of potential strength during threatening displays. Presumably, competitors use each other's displays to assess their relative strengths, and current theory predicts that these signals of strength should generally be honest. We tested this prediction by investigating the relationships among morphology, performance, and social dominance in males of the slender crayfish Cherax dispar. Crayfish routinely use their enlarged front claws (chelae) for both intimidation and fighting, making this species ideal for studying the honesty of weapon size. We evaluated five competing models relating morphological and physiological traits to dominance during paired competitive bouts. Based on the best model, larger chelae clearly resulted in greater dominance however, chela strength had no bearing on dominance. Thus, displays of chela size were dishonest signals of strength, and the enlarged chelae of males seemingly function more for intimidation than for fighting. In addition, an analysis of the performance of isolated chela muscle showed that muscle from male crayfish produced only half the force that muscle from female crayfish produced (236.6+/-26.4 vs. 459.5+/-71.6 kN m(-2)), suggesting that males invest more in developing larger chelae than they do in producing high-quality chela muscle. From our studies of crayfish, we believe dishonest signaling could play a greater role in territorial disputes than previously imagined.
Publisher: Oxford University Press (OUP)
Date: 14-07-2017
DOI: 10.1093/ICB/ICX015
Abstract: All animals experience performance trade-offs as they complete tasks such as capturing prey, defending territories, acquiring mates, and escaping predators. Why then, is it so hard to detect performance trade-offs at the whole-organismal level? Why do we sometimes even obtain positive correlations between two performance traits that are predicted to be negatively associated? Here we explore two plausible explanations. First, most analyses are based on in idual maximal values (i.e., personal best), which could introduce a bias in the correlation estimates. Second, phenotypic correlations alone may be poor indicators of a trade-off when contrasting processes occur at the among- versus within-in idual levels. One such scenario is the "big houses big cars" model developed in life-history theory to explain the existence of "uberfleas" that are superior in all regards (because they acquire more resources than others). We highlight that the exact opposite scenario might occur for performance trade-offs, where among-in idual trade-offs may be masked by within-in idual changes in physical condition. One of the best ways to test among these alternative scenarios is to collect repeated pairs of performance traits and analyze them using multivariate mixed models (MMMs). MMMs allow straightforward and simultaneous examination of trait correlations at the among- and within-in idual levels. We use a simple simulation tool (SQuID package in R) to create a population of Krakens, a mythical giant squid-like sea creature whose morphology generates a performance trade-off between swimming speed and strength or ability to sink ships. The simulations showed that using in idual maximum values introduces a bias that is particularly severe when in iduals differ in the number of repeated s les (ntrial). Finally, we show how MMMs can help detect performance (or any other type of) trade-offs and offer additional insights (e.g., help detect plasticity integration). We hope researchers will adopt MMMs when exploring trade-offs in whole-animal performances.
Publisher: The Royal Society
Date: 07-02-2013
Abstract: During colour signalling in aquatic environments, the colour of the ambient light, the background against which signals are viewed and signal transmission through the environment can all have profound impacts on the efficacy of a given signal. In colour-polymorphic species, where alternative morphs persist owing to a balance in the natural and sexual selection for each, changes to the visual context can have large effects on the local success and relative abundance of competing phenotypes. The ornate rainbowfish, Rhadinocentrus ornatus , is composed of populations that vary in the relative frequency of red and blue in iduals, and inhabit sites that vary in water transmittance from clear (white) to heavily tannin-stained (red-shifted). Using spectroradiometry, we measured the downwelling and sidewelling irradiance, bank radiance and water transmittance of 10 R. ornatus habitats. We found that the relative local abundance of each morph was predicted not by water transmittance but by chromatic differences between the vertical (downwelling light) and horizontal (bank colour) components of the habitat. This visual habitat geometry should increase contrast between the colour signal and background, with large potential to influence the strength of natural and sexual selection in this system.
Publisher: SAGE Publications
Date: 08-06-2015
Abstract: Four studies and a computer simulation tested the hypothesis that people who are overconfident in their self-assessments may be more successful in attracting mates. In Study 1, overconfident people were perceived as more confident in their dating profiles, and this perceived confidence predicted increased romantic desirability. Study 2 revealed that overconfident people also tend to be perceived as arrogant, which counteracts the positive effects of perceived confidence. However, Study 3 revealed that overconfidence might confer an advantage in intrasexual competition, as people were less likely to compete with overconfident in iduals by virtue of their perceived confidence and arrogance. Study 4 showed that overconfident raters were also more likely to choose to compete for romantic partners. In Study 5, agent-based modeling incorporating the coefficients from these studies suggested that overconfidence facilitates mate acquisition in the presence of intrasexual competition.
Publisher: Public Library of Science (PLoS)
Date: 21-02-2018
Publisher: Elsevier BV
Date: 04-2007
Publisher: Wiley
Date: 29-06-2012
DOI: 10.1111/J.1365-2656.2011.01880.X
Abstract: 1. Many prey organisms exhibit adaptive phenotypic plasticity in life-history traits that facilitate a better chance of survival in the presence of predators. The evolution of such plastic traits requires that the defensive phenotype incurs a cost in the absence of predation. 2. Model systems that are used to examine predator-induced defences are often organisms with complex life histories that only induce defences during the larval stage. While many studies have detected costs of inducible defences during the larval stage, detecting the costs of larval defences after metamorphosis is also important. 3. We examine the benefits and costs of inducible larval defences in the urban mosquito, Aedes notoscriptus, by rearing them in the presence and absence of predation cues. We compared survival of larvae inducing behavioural defences, when exposed to predation cues, in predation trials with predatory fish Hypseleotris galii to that of larvae reared in the absence predation cues. We also compared life-history traits of predator-exposed larvae to larvae reared in control conditions. 4. Larvae exposed to chemical predation cues limited activity and were able to avoid predation for longer in trials with H. galii. However, predator-exposed larvae suffered retarded larval growth and development, were smaller at metamorphosis and less resistant to starvation as adults. 5. While it is difficult to understand the 'fitness costs' that poorer starvation resistance might confer to adult mosquitoes, it is likely that smaller adult size of predator-exposed in iduals would reduce fitness, particularly for females where body size limits the size of blood meal they could take to facilitate egg production. We suggest that the demonstrable costs of inducible defences in mosquito larvae make this a good system for testing theoretical models for the evolutionary maintenance of adaptive phenotypic plasticity.
Publisher: Springer Science and Business Media LLC
Date: 14-03-2019
DOI: 10.1007/S00360-019-01212-0
Abstract: The co-evolution of acclimation capacity and thermal performance breadth has been a contentious issue for decades, and little is known regarding the extent to which acclimation alters the shape of acute thermal performance curves. Current acclimation theory suggests that when daily variation is large and unpredictable ectotherms should not acclimate but should evolve wide performance breadths, allowing maintenance of performance across a wide thermal range. The subtropical intertidal zone, however, experiences a large amount of daily thermal variation, but daily means and ranges shift in predictable ways with season, where daily and seasonal variation is roughly equal. We predicted that animals in this habitat would maintain their capacity to acclimate and that performance breadth would not be altered by acclimation to maintain function with rapidly fluctuating daily temperatures. We tested our prediction using a subtropical goby, Bathygobius cocosensis, which lives in tide pools that vary widely, over days and seasons. We exposed B. cocosensis to winter (12-17 °C) and summer (30-35 °C) thermal conditions for six weeks and then measured the thermal dependence of burst swimming speed, routine and maximum metabolic rate, and ventilation rate between 12 and 36 °C. B. cocosensis exhibited an acclimation response for burst swimming speed, maximum metabolic rate and metabolic scope, but acclimation did not alter the shape of acute thermal performance curves. These results indicate that thermal acclimation can occur when short-term thermal variability is large and equal to seasonal variation, and wide performance breadths can be maintained with acclimation in heterogeneous environments.
Publisher: The Company of Biologists
Date: 11-2010
DOI: 10.1242/JEB.046979
Abstract: Organisms adjust to seasonal variability in the environment by responding to cues that indicate environmental change. As most studies of seasonal phenotypic plasticity test only the effect of a single environmental cue, how animals may integrate information from multiple cues to fine-tune plastic responses remains largely unknown. We examined the interaction between correlated (seasonally matching) and conflicting (seasonally opposite) temperature and photoperiod cues on the acclimation of performance traits in male zebrafish, Danio rerio. We acclimated fish for 8 weeks and then tested the change in thermal dependence of maximum burst swimming and feeding rate between 8 and 38°C. We predicted that correlated environmental cues should induce a greater acclimation response than uncorrelated cues. However, we found that only temperature was important for the seasonal acclimation of performance traits in zebrafish. Thermal acclimation shifted the thermal performance curve of both traits. For maximum burst swimming, performance increased for each group near the acclimation temperature and reduced in environments that were far from their acclimation temperature. The feeding rate of cold-acclimated zebrafish was reduced across the test temperature range compared with that of warm-acclimated fish. Our study is the first that has found no effect of the covariation between temperature and photoperiod acclimation cues on locomotor performance in fishes. Our results support the intuitive idea that photoperiod may be a less important seasonal cue for animals living at lower latitudes.
Publisher: The Royal Society
Date: 11-2016
Abstract: Daylight saving time (DST) could reduce collisions with wildlife by changing the timing of commuter traffic relative to the behaviour of nocturnal animals. To test this idea, we tracked wild koalas ( Phascolarctos cinereus ) in southeast Queensland, where koalas have declined by 80% in the last 20 years, and compared their movements with traffic patterns along roads where they are often killed. Using a simple model, we found that DST could decrease collisions with koalas by 8% on weekdays and 11% at weekends, simply by shifting the timing of traffic relative to darkness. Wildlife conservation and road safety should become part of the debate on DST.
Publisher: The Company of Biologists
Date: 2014
DOI: 10.1242/JEB.095620
Abstract: The role of different limbs in supporting and propelling the body has been studied in many species with animals appearing to have either similarity in limb function or differential limb function. Differential hind vs. fore limb function has been proposed as a general feature of running with a sprawling posture and as benefiting sprawled postured animals by enhancing maneuvering and minimizing joint moments. Yet only a few species have been studied and thus the generality of differential limb function in running animals with sprawled postures is unknown. We measured the limb lengths of seven species of lizard and their single limb three-dimensional ground reaction forces during high speed running. We found that most species relied on the hindlimb for producing accelerative forces. Braking forces were either forelimb dominated in fours species and equally distributed between limbs in the other three. Vertical forces were dominated by the hindlimb in three species and equally distributed between the fore- and hindlimb in the other four. Medial forces were dominated by the hindlimb in four species and equally distributed in the other three, with all Iguanians exhibiting hindlimb biased medial forces. Relative hind- to forelimb length of each species was related to variation in hind- vs. fore limb medial forces species with relatively longer hindlimbs compared to forelimbs exhibited medial forces that were more biased towards the hindlimbs. These results suggest that the function of in idual limbs in lizards varies across species with only a single general pattern (hindlimb dominated accelerative force) being present.
Publisher: The Royal Society
Date: 24-02-2010
Abstract: The most commonly assumed cost for exaggerated male ornamentation is increased predation pressure owing to decreased locomotor performance or increased conspicuousness to predators. Despite its intuitive basis, the locomotor costs of male ornamentation are not well established. We tested the hypothesis that multiple male signals that are used independently during female choice and male competition could lead to varied locomotor costs. Multiple signals with varied costs could provide a more detailed indicator of overall male quality, as only the highest-quality in iduals could support all costs. To test this idea, we investigated the burst locomotor consequences of multiple ornaments for males of the pacific blue-eye ( Pseudomugil signifer ). We evaluated five competing models relating body size, ornament size and performance traits to field measures of dominance and attractiveness. Non-propulsive male fin ornaments used during male competition were different from those used in female choice. First dorsal fin length was the most important predictor of male attractiveness, while dominance was only associated with anal fin length. Furthermore, first dorsal fin length was positively correlated with swim speed, while anal fin length was negatively associated with speed. Our study shows that multiple male signals that are used independently during male competition and female choice also differ in their associated costs. This provides a mechanism for understanding why locomotor costs for exaggerated male ornamentation are not often empirically demonstrated.
Publisher: Springer Science and Business Media LLC
Date: 02-02-2010
DOI: 10.1007/S00360-010-0445-2
Abstract: The strategies used by ectotherms to minimise the detrimental effects of suboptimal thermal environments on physiological performance are often related to whether they inhabit a terrestrial or aquatic environment. Most terrestrial ectotherms use thermoregulatory strategies to maintain body temperature within an optimal range, while many aquatic ectotherms utilise thermal acclimation to maintain performance over varying seasonal temperatures. This study aimed to elucidate the relative contributions of acclimation and behavioural thermoregulation to maintaining whole-animal performance over varying seasonal temperatures in the semi-terrestrial Lamington spiny crayfish (Euastacus sulcatus). Crayfish activity and surface temperatures were determined by means of radio tracking and behavioural observations. Field studies demonstrated that E. sulcatus is exposed to stable daily temperatures, varying only between seasons from 10 degrees C in late winter to over 20 degrees C in summer. Also, terrestrial behaviour corresponded to a small portion of crayfish time (1.13%), much lower than predicted, indicating that E. sulcatus has limited opportunity for behavioural thermoregulation. We also tested the effect of acclimation to either 10 or 20 degrees C on chela strength and stamina. We found acclimation had a more marked effect on chela stamina than maximum strength measures however, overall acclimatory capacity was limited in E. sulcatus. Thus, we found that the semi-terrestrial crayfish E. sulcatus used neither thermoregulatory behaviours nor physiological strategies to deal with seasonal changes in environmental temperature.
Publisher: Oxford University Press (OUP)
Date: 31-07-2016
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.JBIOMECH.2018.03.003
Abstract: In many sports, athletes perform motor tasks that simultaneously require both speed and accuracy for success, such as kicking a ball. Because of the biomechanical trade-off between speed and accuracy, athletes must balance these competing demands. Modelling the optimal compromise between speed and accuracy requires one to quantifyhow task speed affects the dispersion around a target, a level of experimental detail not previously addressed. Using soccer penalties as a system, we measured two-dimensional kicking error over a range of speeds, target heights, and kicking techniques. Twenty experienced soccer players executed a total of 8466 kicks at two targets (high and low). Players kicked with the side of their foot or the instep at ball speeds ranging from 40% to 100% of their maximum. The inaccuracy of kicks was measured in horizontal and vertical dimensions. For both horizontal and vertical inaccuracy, variance increased as a power function of speed, whose parameter values depended on the combination of kicking technique and target height. Kicking precision was greater when aiming at a low target compared to a high target. Side-foot kicks were more accurate than instep kicks. The centre of the dispersion of shots shifted as a function of speed. An analysis of the covariance between horizontal and vertical error revealed right-footed kickers tended to miss below and to the left of the target or above and to the right, while left-footed kickers tended along the reflected axis. Our analysis provides relationships needed to model the optimal strategy for penalty kickers.
Publisher: CRC Press
Date: 11-07-2205
DOI: 10.1201/B10190
Publisher: Elsevier BV
Date: 05-2004
Publisher: University of Chicago Press
Date: 11-2005
DOI: 10.1086/432923
Abstract: During metamorphosis, most hibians undergo rapid shifts in their morphology that allow them to move from an aquatic to a more terrestrial existence. Two important challenges associated with this shift in habitat are the necessity to switch from an aquatic to terrestrial mode of locomotion and changes in the thermal environment. In this study, I investigated the consequences of metamorphosis to the burst swimming and running performance of the European newt Triturus cristatus to determine the nature and magnitude of any locomotor trade-offs that occur across life-history stages. In addition, I investigated whether there were any shifts in the thermal dependence of performance between life-history stages of T. cristatus to compensate for changes in their thermal environment during metamorphosis. A trade-off between swimming and running performance was detected across life-history stages, with metamorphosis resulting in a simultaneous decrease in swimming and increase in running performance. Although the terrestrial habitat of postmetamorphic stages of the newt T. cristatus experienced greater daily fluctuations in temperature than the aquatic habitat of the larval stage, no differences in thermal sensitivity of locomotor performance were detected between the larval aquatic and postmetamorphic stages. The absence of variation across life-history stages of T. cristatus may indicate that thermal sensitivity may be a conservative trait across ontogenetic stages in hibians, but further studies are required to investigate this assertion.
Publisher: The Royal Society
Date: 02-2023
DOI: 10.1098/RSOS.221180
Abstract: Semelparity is a breeding strategy whereby an in idual invests large amounts of resources into a single breeding season, leading to the death of the in idual. Male northern quolls ( Dasyurus hallucatus ) are the largest known mammal to experience a post-breeding die-off however, the cause of their death is unknown, dissimilar from causes in other semelparous dasyurids. To identify potential differences between male northern quolls that breed once, and females that can breed for up to four seasons, the behaviours, activity budgets, speeds and distances travelled were examined. Northern quolls were captured on Groote Eylandt off the coast of the Northern Territory, Australia, and were fitted with accelerometers. A machine learning algorithm (Self-organizing Map) was trained on more than 76 h of recorded footage of quoll behaviours and used to predict behaviours in 42 days of data from wild roaming quolls (7M : 6F). Male northern quolls were more active (male 1.27 g , s.d. = 0.41 female 1.18 g, s.d. = 0.36), spent more time walking (13.09% male: 8.93% female) and engaged in less lying/resting behaviour than female northern quolls (7.67% male: 23.65% female). Reduced resting behaviour among males could explain the post-breeding death as the deterioration in appearance reflects that reported for sleep-deprived rodents.
Publisher: Public Library of Science (PLoS)
Date: 31-12-2018
Publisher: Oxford University Press (OUP)
Date: 02-09-2015
DOI: 10.1093/ICB/ICV103
Abstract: The ability for prey to escape a pursuing predator is dependent both on the prey's speed away from the threat and on their ability to rapidly change directions, or maneuverability. Given that the biomechanical trade-off between speed and maneuverability limits the simultaneous maximization of both performance traits, animals should not select their fastest possible speeds when running away from a pursuing predator but rather a speed that maximizes the probability of successful escape. We explored how variation in the relationship between speed and maneuverability-or the shape of the trade-off-affects the optimal choice of speed for escaping predators. We used tablet-based games that simulated interactions between predators and prey (human subjects acting as predators attempting to capture "prey" moving across a screen). By defining a specific relationship between speed and maneuverability, we could test the survival of each of the possible behavioral choices available to this phenotype, i.e., the best combination of speed and maneuverability for prey fitness, based on their ability to escape. We found that the shape of the trade-off function affected the prey's optimal speed for success in escaping, the prey's maximum performance in escaping, and the breadth of speeds over which the prey's performance was high. The optimal speed for escape varied only when the trade-off between speed and maneuverability was non-linear. Phenotypes possessing trade-off functions for which maneuverability was only compromised at high speeds exhibited lower optimal speeds. Phenotypes that exhibited greater increases in maneuverability for any decrease in speed were more likely to have broader ranges of performance, meaning that in iduals could attain their maximum performance across a broader range of speeds. We also found that there was a differential response of the subject's learning to these different components of locomotion. With increased experience through repeated trials, subjects were able to successfully catch faster and faster dots. However, no improvement was observed in the subject's ability to capture more maneuverable prey. Our work highlights the costs of high-speed movement on other traits, including maneuverability, which make the use of an animal's fastest speeds unlikely, even when attempting to escape predators. By investigating the shape of the trade-off functions between speed and maneuverability and the way the environment and morphology mediates this trade-off, we can begin to understand why animals choose to move at the speeds they do when they are running away from predators or attempting to capture prey.
Publisher: The Company of Biologists
Date: 03-2013
DOI: 10.1242/JEB.079756
Abstract: Aggressive behaviour is linked to fitness, but it is metabolically costly. Changes in metabolic demand during the reproductive cycle could constrain activity and thereby modulate behavioural phenotypes. We predicted that increased metabolic demands in late pregnancy would lead to reduced aggression and a lower metabolic cost of behaviour in the mosquitofish Gambusia holbrooki. Contrary to our prediction, females became more aggressive in late pregnancy, but metabolic scope (i.e. the metabolic energy available for activity and behaviour) decreased. Consequently, late-stage pregnant females spent significantly more of their available metabolic scope on aggressive behaviour. Hence, as pregnancy progressed, females showed increasingly risky behaviour by depleting metabolic resources available for activities other than fighting. We argue that the metabolic cost of behaviour, and possibly personality, is best expressed with reference to metabolic scope, rather than resting metabolic rates or concentrations of metabolites. This dependence on metabolic scope could render reproductive success sensitive to environmental changes.
Publisher: The Company of Biologists
Date: 06-2011
DOI: 10.1242/JEB.054478
Abstract: Human-induced climate change is predicted to affect not only the mean temperature of the environment but also the variability and frequency of extreme climatic events. Variability in an organism's developmental environment has the potential to markedly affect an in idual's growth trajectory and physiological function, leading to impacts on in idual fitness and population dynamics. Thus, it is important to consider the consequences of thermal variability on developing organisms and understand their capacity to respond to such increased variation. We investigated the capacity of larval striped marsh frogs (Limnodynastes peronii) to initiate a response to increases in the thermal variability of their developmental environment by reducing the sensitivity of their physiological rate functions to changes in temperature. In variable environments, we expected the thermal sensitivity of rate functions to decrease and their performance breadth to widen so as to buffer the effect of thermal variability. We raised larvae in stable (24°C), narrowly variable (22–26°C mean 24°C) and widely variable (14–34°C mean 24°C) thermal environments and measured the thermal sensitivity of their locomotor performance, heart rate, oxygen consumption and activities of two metabolic enzymes, lactate dehydrogenase and cytochrome c oxidase. We found that the temperature-dependent relationships of these physiological functions did not differ between tadpoles raised in stable or variable thermal conditions. Furthermore, the Q10 values of each response variable were virtually unaffected by treatment when measured over the entire thermal range. Our results reveal that larval hibians exhibit little plasticity in metabolic traits to thermal variability. This lack of plasticity may have important implications for the growth and population dynamics of organisms in environments that are beginning to experience increased thermal variability.
Publisher: The Company of Biologists
Date: 2015
DOI: 10.1242/JEB.120857
Abstract: Males of many species use signals during aggressive contests to communicate their fighting capacity. These signals are usually reliable indicators of an in idual's underlying quality, however, in several crustacean species, displays of weapons do not always accurately reflect the attribute being advertised. Male fiddler crabs possess one enlarged claw that is used to attract females and to intimidate opponents during territorial contests. After the loss of their major, claw males can regenerate a replacement claw that is similar in size but considerably weaker. As this inferior weapon can still be used to successfully intimidate rivals, it represents one of the clearest cases of unreliable signalling of strength during territorial contests. We investigated the functional mechanisms that govern signal reliability in the two-toned fiddler crab, Uca vomeris. Male U. vomeris exhibit both reliable and unreliable signals of strength via the expression of original and regenerated claw morphs. We examined the morphological, biomechanical and biochemical characteristics of original and regenerated claws to establish the best predictors of variation in claw strength. For a given claw size, regenerated claws have less muscle mass than original claws, and for a given muscle mass regenerated claws were significantly weaker than original claws. The mechanical advantage was also lower in regenerated claws compared with original claws. However, the activity of three catabolic enzymes did not differ between claw types. We concluded that the structural and physiological predictors of force production influence the frequencies of reliable and unreliable signals of strength in U. vomeris. This study furthers our understanding of the proliferation of unreliable signals in natural populations.
Publisher: Wiley
Date: 26-03-2007
Publisher: Informa UK Limited
Date: 18-06-2020
Publisher: CRC Press
Date: 13-01-2019
Publisher: The Company of Biologists
Date: 15-02-2012
DOI: 10.1242/JEB.058032
Abstract: Physiological ecologists have long sought to understand the plasticity of organisms in environments that vary widely among years, seasons and even hours. This is now even more important because human-induced climate change is predicted to affect both the mean and variability of the thermal environment. Although environmental change occurs ubiquitously, relatively few researchers have studied the effects of fluctuating environments on the performance of developing organisms. Even fewer have tried to validate a framework for predicting performance in fluctuating environments. Here, we determined whether reaction norms based on performance at constant temperatures (18, 22, 26, 30 and 34°C) could be used to predict embryonic and larval performance of anurans at fluctuating temperatures (18–28°C and 18–34°C). Based on existing theory, we generated hypotheses about the effects of stress and acclimation on the predictability of performance in variable environments. Our empirical models poorly predicted the performance of striped marsh frogs (Limnodynastes peronii) at fluctuating temperatures, suggesting that extrapolation from studies conducted under artificial thermal conditions would lead to erroneous conclusions. During the majority of ontogenetic stages, growth and development in variable environments proceeded more rapidly than expected, suggesting that acute exposures to extreme temperatures enable greater performance than do chronic exposures. Consistent with theory, we predicted performance more accurately for the less variable thermal environment. Our results underscore the need to measure physiological performance under naturalistic thermal conditions when testing hypotheses about thermal plasticity or when parameterizing models of life-history evolution.
Publisher: Oxford University Press (OUP)
Date: 22-10-2015
DOI: 10.1093/ICB/ICV106
Abstract: An animal's movement speed affects all behaviors and underlies the intensity of an activity, the time it takes to complete it, and the probability of successfully completing it, but which factors determine how fast or slow an animal chooses to move? Despite the critical importance of an animal's choice of speed (hereafter designated as "speed-choice"), we still lack a framework for understanding and predicting how fast animals should move in nature. In this article, we develop a framework for predicting speed that is applicable to any animal-including humans-performing any behavior where choice of speed occurs. To inspire new research in this area, we (1) detail the main factors likely to affect speed-choice, including organismal constraints (i.e., energetic, physiological, and biomechanical) and environmental constraints (i.e., predation intensity and abiotic factors) (2) discuss the value of optimal foraging theory in developing models of speed-choice and (3) describe how optimality models might be integrated with the range of potential organismal and environmental constraints to predict speed. We show that by utilizing optimality theory it is possible to provide quantitative predictions of optimal speeds across different ecological contexts. However, the usefulness of any predictive models is still entirely dependent on being able to provide relevant mathematical functions to insert into such models. We still lack basic knowledge about how an animal's speed affects its motor control, maneuverability, observational skills, and vulnerability to predators. Studies exploring these gaps in knowledge will help facilitate the field of optimal performance and allow us to adequately parameterize models predicting the speed-choice of animals, which represents one of the most basic of all behavioral decisions.
Publisher: Oxford University Press (OUP)
Date: 22-10-2015
DOI: 10.1093/ICB/ICV107
Abstract: Speed of movement is fundamental to animal behavior-defining the intensity of a task, the time needed to complete it, and the likelihood of success-but how does an animal decide how fast to move? Most studies of animal performance measure maximum capabilities, but animals rarely move at their maximum in the wild. It was the goal of our symposium to develop a conceptual framework to explore the choices of speed in nature. A major difference between our approach and previous work is our move toward understanding optimal rather than maximal speeds. In the following series of papers, we provide a starting point for future work on animal movement speeds, including a conceptual framework, a simple optimality model, an evolutionary context, and an exploration of the various biomechanical and energetic constraints on speed. By applying a cross-disciplinary approach to the study of the choice of speed-as we have done here-we can reveal much about the way animals use habitats, interact with conspecifics, avoid predators, obtain food, and negotiate human-modified landscapes.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.ENVPOL.2017.10.088
Abstract: Mining is fundamental to the Australian economy, yet little is known about how potential contaminants bioaccumulate and affect wildlife living near active mining sites. Here, we show using air s ling that fine manganese dust within the respirable size range is found at levels exceeding international recommendations even 20 km from manganese extraction, processing, and storage facilities on Groote Eylandt, Northern Territory. Endangered northern quolls (Dasyurus hallucatus) living near mining sites were found to have elevated manganese concentrations within their hair, testes, and in two brain regions-the neocortex and cerebellum, which are responsible for sensory perception and motor function, respectively. Accumulation in these organs has been associated with adverse reproductive and neurological effects in other species and could affect the long-term population viability of northern quolls.
Publisher: Informa UK Limited
Date: 26-02-2016
DOI: 10.1080/02640414.2016.1151544
Abstract: The development of a comprehensive protocol for quantifying soccer-specific skill could markedly improve both talent identification and development. Surprisingly, most protocols for talent identification in soccer still focus on the more generic athletic attributes of team sports, such as speed, strength, agility and endurance, rather than on a player's technical skills. We used a multivariate methodology borrowed from evolutionary analyses of adaptation to develop our quantitative assessment of in idual soccer-specific skill. We tested the performance of 40 in idual academy-level players in eight different soccer-specific tasks across an age range of 13-18 years old. We first quantified the repeatability of each skill performance then explored the effects of age on soccer-specific skill, correlations between each of the pairs of skill tasks independent of age, and finally developed an in idual metric of overall skill performance that could be easily used by coaches. All of our measured traits were highly repeatable when assessed over a short period and we found that an in idual's overall skill - as well as their performance in their best task - was strongly positively correlated with age. Most importantly, our study established a simple but comprehensive methodology for assessing skill performance in soccer players, thus allowing coaches to rapidly assess the relative abilities of their players, identify promising youths and work on eliminating skill deficits in players.
Publisher: The Company of Biologists
Date: 15-11-2010
DOI: 10.1242/JEB.043356
Abstract: One of the more common patterns of offspring size variation is that mothers tend to produce larger offspring at lower temperatures. Whether such variation is adaptive remains unclear. Determining whether optimal offspring size differs between thermal environments provides a direct way of assessing the adaptive significance of temperature-driven variation in egg size. Here, we examined the relationship between offspring size and performance at three temperatures for several important fitness components in the zebra fish, Danio rerio. The effects of egg size on performance were highly variable among life-history stages (i.e. pre- and post-hatching) and dependent on the thermal environment offspring size positively affected performance at some temperatures but negatively affected performance at others. When we used these data to generate a simple optimality model, the model predicted that mothers should produce the largest size offspring at the lowest temperature, offspring of intermediate size at the highest temperature and the smallest offspring at the intermediate temperature. An experimental test of these predictions showed that the rank order of observed offspring sizes produced by mothers matched our predictions. Our results suggest that mothers adaptively manipulate the size of their offspring in response to thermally driven changes in offspring performance and highlight the utility of optimality approaches for understanding offspring size variation.
Publisher: Oxford University Press (OUP)
Date: 2011
Publisher: Wiley
Date: 22-01-2018
Publisher: Wiley
Date: 13-06-2017
Publisher: Informa UK Limited
Date: 26-07-2021
DOI: 10.1080/24733938.2021.1899274
Abstract: Kicking powerfully and accurately is essential in soccer, and players who kick proficiently with both feet are highly sought after. Assessing performance in youth players is often confounded by more physically developed players outperforming their smaller peers. To alleviate such bias, we present a testing protocol and normative data developed with an elite Brazilian soccer academy that controls for players' age and size to assess kick performance with both feet. We measured kick speed and kick accuracy of 178 players and recorded their age (10-20 years), height, and mass. Combining age, height, and mass into an age and size index (ASI), we developed equations describing the relationship between ASI and performance. To determine the underlying predictors of performance, we also measured sprint ability and soccer-specific motor control of each foot with ball dribbling tasks. Kicking speed with the dominant foot was predicted by ASI, sprint speed, and motor control of the nondominant foot, while kicking speed with the nondominant foot was predicted by ASI and motor control of the nondominant foot. Kick accuracy with each foot was predicted by ASI and motor control of the corresponding foot. To improve kicking performance, we suggest training programs focus on motor control.
Publisher: University of Chicago Press
Date: 03-2000
DOI: 10.1086/316730
Abstract: The effect of ontogenetic increases in total length on burst swimming performance was investigated in tadpoles of the striped marsh frog (Limnodynastes peronii) over the total-length range of 1. 5-4 cm and Gosner developmental stages 25-38. The burst swimming performance of tadpoles at 10 degrees and 24 degrees C was determined by videotaping startle responses with a high-speed video camera at 200 Hz and analysing the sequences frame by frame. Maximum swimming velocity (Umax) and acceleration (Amax) increased with total length (L) at a rate that was proportionally greater than the increase in total length (i.e., positive allometry exponents >1) and was described by the allometric equations Umax=0.061L1.34 and Amax=1.15L1.11 at 10 degrees C and Umax=0.114L1.34 and Amax=1.54L1. 11 at 24 degrees C. Stride length increased with a total-length exponent of approximately 1 but was unaffected by temperature. Tail-beat frequency was not affected by total length and increased from 7.8+/-0.2 Hz at 10 degrees C to 21.7+/-0.7 Hz at 24 degrees C. Developmental stage did not significantly influence the relationship between total length and Umax or Amax. Furthermore, temperature and the associated changes in water viscosity did not affect the relationship between total length and burst swimming performance. At their Umax, Reynolds numbers ranged from approximately 1,500 in the smaller tadpoles up to 50,000 for the larger animals at 24 degrees C. We suggest the positive allometry of Umax in larval L. peronii was due in part to the increases in tail width (TW) with total length (TW=-1.36L1.66), possibly reflecting the increasing importance of burst swimming performance to survival during larval development.
Publisher: Elsevier BV
Date: 11-2010
Publisher: Informa UK Limited
Date: 23-11-2019
DOI: 10.1080/02640414.2018.1544110
Abstract: This study assessed whether a new, closed-skill dribbling or sprinting task could predict attacking performance in soccer. Twenty-five male players were recruited from the Londrina Junior Team Football Academy in Brazil and asked to either dribble the ball or sprint through five custom circuits that varied in average curvature (0-1.37 radians.m
Publisher: Springer Science and Business Media LLC
Date: 02-2002
DOI: 10.1038/415755B
Publisher: The Royal Society
Date: 07-2017
Abstract: How extinct, non-avian theropod dinosaurs locomoted is a subject of considerable interest, as is the manner in which it evolved on the line leading to birds. Fossil footprints provide the most direct evidence for answering these questions. In this study, step width—the mediolateral (transverse) distance between successive footfalls—was investigated with respect to speed (stride length) in non-avian theropod trackways of Late Triassic age. Comparable kinematic data were also collected for humans and 11 species of ground-dwelling birds. Permutation tests of the slope on a plot of step width against stride length showed that step width decreased continuously with increasing speed in the extinct theropods ( p 0.001), as well as the five tallest bird species studied ( p 0.01). Humans, by contrast, showed an abrupt decrease in step width at the walk–run transition. In the modern bipeds, these patterns reflect the use of either a discontinuous locomotor repertoire, characterized by distinct gaits (humans), or a continuous locomotor repertoire, where walking smoothly transitions into running (birds). The non-avian theropods are consequently inferred to have had a continuous locomotor repertoire, possibly including grounded running. Thus, features that characterize avian terrestrial locomotion had begun to evolve early in theropod history.
Publisher: Springer Science and Business Media LLC
Date: 07-05-2001
Abstract: We examined the burst swimming performance of two Antarctic fishes, Trematomus bernacchii and T. centronotus, at five temperatures between -1 degrees C and 10 degrees C. As Antarctic fishes are considered one of the most cold specialised and stenothermal of all ectotherms, we predicted they would possess a narrow thermal performance breadth for burst swimming and a correlative decrease in performance at high temperatures. Burst swimming was assessed by videotaping swimming sequences with a 50-Hz video camera and analysing the sequences frame-by-frame to determine maximum velocity, the distance moved throughout the initial 200 ms, and the time taken to reach maximum velocity. In contrast to our prediction, we found both species possessed a wide thermal performance breadth for burst swimming. Although maximum swimming velocity for both T. bernacchii and T. centronotus was significantly highest at 6 degrees C, maximum velocity at all other test temperatures was less than 20% lower. Thus, it appears that specialisation to a highly stable and cold environment is not necessarily associated with a narrow thermal performance breadth for burst swimming in Antarctic fish. We also examined the ability of the Antarctic fish Pagothenia borchgrevinki to acclimate their burst-swimming performance to different temperatures. We exposed P. borchgrevinki to either -1 degrees C or 4 degrees C for 4 weeks and tested their burst-swimming performance at four temperatures between -1 degrees C and 10 degrees C. Burst-swimming performance of Pagothenia borchgrevinki was unaffected by exposure to either -1 degrees C or 4 degrees C for 4 weeks. Maximum swimming velocity of both acclimation groups was thermally independent over the total temperature range of 1 degrees C to 10 degrees C. Therefore, the loss of any capacity to restructure the phenotype and an inability to thermally acclimate swimming performance appears to be associated with inhabiting a highly stable thermal environment.
Publisher: Wiley
Date: 26-10-2007
Publisher: Springer Science and Business Media LLC
Date: 09-2012
DOI: 10.1007/S00360-011-0611-1
Abstract: In nature, many organisms alter their developmental trajectory in response to environmental variation. However, studies of thermal acclimation have historically involved stable, unrealistic thermal treatments. In our study, we incorporated ecologically relevant treatments to examine the effects of environmental stochasticity on the thermal acclimation of the fall field cricket (Gryllus pennsylvanicus). We raised crickets for 5 weeks at either a constant temperature (25°C) or at one of three thermal regimes mimicking a seasonal decline in temperature (from 25 to 12°C). The latter three treatments differed in their level of thermal stochasticity: crickets experienced either no diel cycle, a predictable diel cycle, or an unpredictable diel cycle. Following these treatments, we measured several traits considered relevant to survival or reproduction, including growth rate, jumping velocity, feeding rate, metabolic rate, and cold tolerance. Contrary to our predictions, the acclimatory responses of crickets were unrelated to the magnitude or type of thermal variation. Furthermore, acclimation of performance was not ubiquitous among traits. We recommend additional studies of acclimation in fluctuating environments to assess the generality of these findings.
Publisher: The Company of Biologists
Date: 15-02-2014
DOI: 10.1242/JEB.092056
Abstract: Why are performance trade-offs so rarely detected in animals when their underlying physiological basis seems so intuitive? One possibility is that in idual variation in health, fitness, nutrition, development or genetics, or 'in idual quality', makes some in iduals better or worse performers across all motor tasks. If this is the case, then correcting for in idual quality should reveal functional trade-offs that might otherwise be overlooked. We tested this idea by exploring trade-offs in maximum physical performance and motor skill function in semi-professional soccer players. We assessed in idual performance across five maximum 'athletic' tasks providing independent measures of power, stamina and speed, as well as five soccer-specific 'motor skill' tasks providing independent measures of foot control. We expected to find functional trade-offs between pairs of traits (e.g. endurance versus power/speed tasks or specialist-generalist performance) - but only after correcting for in idual quality. Analyses of standardised raw data found positive associations among several pairs of traits, but no evidence of performance trade-offs. Indeed, peak performance across a single athletic task (degree of specialisation) was positively associated with performance averaged across all other athletic tasks (generalist). However, after accounting for an in idual's overall quality, several functional trade-offs became evident. Within our quality-corrected data, 1500 m-speed (endurance) was negatively associated with squat time (power), jump distance (power) and agility speed - reflecting the expected speed-endurance trade-off and degree of specialisation was negatively associated with average performance across tasks. Taken together, our data support the idea that in idual variation in general quality can mask the detection of performance trade-offs at the whole-animal level. These results highlight the possibility that studies may spuriously conclude certain functional trade-offs are unimportant or non-existent when analyses that account for variation in general quality may reveal their cryptic presence.
Publisher: Elsevier BV
Date: 02-2002
Publisher: Wiley
Date: 24-04-2021
DOI: 10.1111/SMS.13969
Abstract: We designed and tested a protocol for measuring the performance of in iduals in small‐sided soccer games. We tested our protocol on three different groups of youth players from elite Brazilian football academies. Players in each group played a series of 3v3 games, in which in iduals were randomly assigned into new teams and against new opponents for each game. We calculated each in idual's average in idual goals scored, goals scored by teammates, goals conceded, and net team goals per game. Our protocol was consistent across days and repeatable across groups, with intraclass correlation coefficients (ICCs) of 0.57–0.69 for average net goals per game across testing days. Players could achieve high success by scoring goals or ensuring their team concede few goals. We also calculated the first and second dimension of a principal component analysis based on each player's number of goals scored, goals scored by teammates, and number of goals conceded per game. Players that were overall high performers had higher PC 1 scores, while PC 2 scores represented the type of contribution made by a player to overall performance. Positive PC 2 values were indicative of high number of in idual goals while negative values were associated with more goals from teammates and fewer conceded goals. Our design allows coaches and scouts to easily collect a robust metric of in idual performance using randomly designed, small‐sided games. We also provide simulations that allow one to apply our methodology for in idual talent identification to other small‐sided games in any team sport.
Publisher: The Royal Society
Date: 07-05-2004
Publisher: The Royal Society
Date: 26-01-2011
Abstract: Increased ultraviolet-B (UV-B) radiation as a consequence of ozone depletion is one of the many potential drivers of ongoing global hibian declines. Both alone and in combination with other environmental stressors, UV-B is known to have detrimental effects on the early life stages of hibians, but our understanding of the fitness consequences of these effects remains superficial. We examined the independent and interactive effects of UV-B and predatory chemical cues (PCC) on a suite of traits of Limnodynastes peronii embryos and tadpoles, and assessed tadpole survival time in a predator environment to evaluate the potential fitness consequences. Exposure to a 3 to 6 per cent increase in UV-B, which is comparable to changes in terrestrial UV-B associated with ozone depletion, had no effect on any of the traits measured, except survival time in a predator environment, which was reduced by 22 to 28 per cent. Exposure to PCC caused tadpoles to hatch earlier, have reduced hatching success, have improved locomotor performance and survive for longer in a predator environment, but had no effect on tadpole survival, behaviour or morphology. Simultaneous exposure to UV-B and PCC resulted in no interactive effects. These findings demonstrate that increased UV-B has the potential to reduce tadpole fitness, while exposure to PCCs improves their fitness.
Publisher: The Company of Biologists
Date: 2013
DOI: 10.1242/JEB.083063
Abstract: One of the more intuitive viability costs that can result from the possession of exaggerated sexually selected traits is increased predation pressure due to reduced locomotor capacity. Despite mixed empirical support for such locomotor costs, recent studies suggest such costs may be masked by compensatory traits that effectively offset any detrimental effects. In this study, we provide a comprehensive assessment of the locomotor costs associated with improved male-male competitive ability by simultaneously testing for locomotor trade-offs and potential compensatory mechanisms in territorial male and non-territorial female geckos. Fighting capacity and escape performance of male Asian house geckos (Hemidactylus frenatus) are likely to pose conflicting demands on the optimum phenotype for each task. Highly territorial and aggressive males may require greater investment in head size/strength but such an enhancement may affect overall escape performance. Among male geckos, we found that greater biting capacity due to larger head size was associated with reduced sprint performance this trade-off was further exacerbated when sprinting on an incline. Females, however, showed no evidence of this trade-off on either flat or inclined surfaces. The sex specificity of this trade-off suggests that the sexes differ in their optimal strategies for dealing with the conflicting requirements of bite force and sprint speed. Unlike males, female H. frenatus had a positive association between hind-limb lengths and head size, suggesting that they have utilised a compensatory mechanism to alleviate for the possible locomotor costs of larger head sizes. It appears that there is greater selection on traits that improve fighting ability (bite force) for males but it is viability traits (sprint speed) that appear to be of greater importance for females. Our results emphasise that only by examining both functional trade-offs and potential compensatory mechanisms is it possible to discover the varied mechanisms affecting the morphological design of a species.
Publisher: University of Chicago Press
Date: 03-2006
DOI: 10.1086/499990
Abstract: Over the last 50 yr, thermal biology has shifted from a largely physiological science to a more integrated science of behavior, physiology, ecology, and evolution. Today, the mechanisms that underlie responses to environmental temperature are being scrutinized at levels ranging from genes to organisms. From these investigations, a theory of thermal adaptation has emerged that describes the evolution of thermoregulation, thermal sensitivity, and thermal acclimation. We review and integrate current models to form a conceptual model of coadaptation. We argue that major advances will require a quantitative theory of coadaptation that predicts which strategies should evolve in specific thermal environments. Simply combining current models, however, is insufficient to understand the responses of organisms to thermal heterogeneity a theory of coadaptation must also consider the biotic interactions that influence the net benefits of behavioral and physiological strategies. Such a theory will be challenging to develop because each organism's perception of and response to thermal heterogeneity depends on its size, mobility, and life span. Despite the challenges facing thermal biologists, we have never been more pressed to explain the ersity of strategies that organisms use to cope with thermal heterogeneity and to predict the consequences of thermal change for the ersity of communities.
Publisher: Oxford University Press (OUP)
Date: 08-08-2015
DOI: 10.1093/ICB/ICV091
Abstract: How fast should animals move when trying to survive? Although many studies have examined how fast animals can move, the fastest speed is not always best. For ex le, an in idual escaping from a predator must run fast enough to escape, but not so fast that it slips and falls. To explore this idea, we developed a simple mathematical model that predicts the optimal speed for an in idual running from a predator along a straight beam. A beam was used as a proxy for straight-line running with severe consequences for missteps. We assumed that success, defined as reaching the end of the beam, had two broad requirements: (1) running fast enough to escape a predator, and (2) minimizing the probability of making a mistake that would compromise speed. Our model can be tailored to different systems by revising the predator's maximal speed, the prey's stride length and motor coordination, and the dimensions of the beam. Our model predicts that animals should run slower when the beam is narrower or when coordination is worse.
Publisher: The Royal Society
Date: 29-11-2017
Abstract: Just as evolutionary biologists endeavour to link phenotypes to fitness, sport scientists try to identify traits that determine athlete success. Both disciplines would benefit from collaboration, and to illustrate this, we used an analytical approach common to evolutionary biology to isolate the phenotypes that promote success in soccer, a complex activity of humans played in nearly every modern society. Using path analysis, we quantified the relationships among morphology, balance, skill, athleticism and performance of soccer players. We focused on performance in two complex motor activities: a simple game of soccer tennis (1 on 1), and a standard soccer match (11 on 11). In both contests, players with greater skill and balance were more likely to perform better. However, maximal athletic ability was not associated with success in a game. A social network analysis revealed that skill also predicted movement. The relationships between phenotypes and success during in idual and team sports have potential implications for how selection acts on these phenotypes, in humans and other species, and thus should ultimately interest evolutionary biologists. Hence, we propose a field of evolutionary sports science that lies at the nexus of evolutionary biology and sports science. This would allow biologists to take advantage of the staggering quantity of data on performance in sporting events to answer evolutionary questions that are more difficult to answer for other species. In return, sports scientists could benefit from the theoretical framework developed to study natural selection in non-human species.
Publisher: Wiley
Date: 19-04-2006
DOI: 10.1111/J.1365-2656.2006.01089.X
Abstract: 1. To survive adverse or unpredictable conditions in the ontogenetic environment, many organisms retain a level of phenotypic plasticity that allows them to meet the challenges of rapidly changing conditions. Larval anurans are widely known for their ability to modify behaviour, morphology and physiological processes during development, making them an ideal model system for studies of environmental effects on phenotypic traits. Although temperature is one of the most important factors influencing the growth, development and metamorphic condition of larval anurans, many studies have failed to include ecologically relevant thermal fluctuations among their treatments. 2. We compared the growth and age at metamorphosis of striped marsh frogs Limnodynastes peronii raised in a diurnally fluctuating thermal regime and a stable regime of the same mean temperature. We then assessed the long-term effects of the larval environment on the morphology and performance of post-metamorphic frogs. 3. Larval L. peronii from the fluctuating treatment were significantly longer throughout development and metamorphosed about 5 days earlier. Frogs from the fluctuating group metamorphosed at a smaller mass and in poorer condition compared with the stable group, and had proportionally shorter legs. 4. Frogs from the fluctuating group showed greater jumping performance at metamorphosis and less degradation in performance during a 10-week dormancy. Treatment differences in performance could not be explained by whole-animal morphological variation, suggesting improved contractile properties of the muscles in the fluctuating group.
Publisher: SAGE Publications
Date: 11-08-2023
DOI: 10.1177/17479541221117630
Abstract: In many youth sports, selection into elite training academies is dominated by athletes born earlier in the year. Previous research suggests this is partly due to these athletes being more physically developed than their younger peers. How athletes born later in the year survive in elite academies is less understood. Here, we tested the hypothesis that players born later in the year are more technically skilled than their peers born earlier in the same year. Using 150 youth players (10–19 years of age) from an elite Brazilian soccer academy, we measured each player's date of birth, height, and mass sprinting ability dribbling ability and kicking accuracy and speed. We found most players in this academy were born in the first half of the year, and those born earlier in the year (relatively older) tended to be taller and heavier than those born later in the same year (relatively younger). In addition, relatively older players were faster when sprinting and dribbling the ball in a straight line. Conversely, relatively younger players were more accurate when passing the ball with their nondominant foot, providing some evidence these players were more technically skilled than their older peers of the same age. We suggest skill tests with youth players need to consider relative age and physical size in order to best assess a player's potential.
Publisher: Hindawi Limited
Date: 08-04-2020
DOI: 10.1002/TSM2.142
Publisher: Wiley
Date: 26-07-2005
Start Date: 07-2003
End Date: 07-2006
Amount: $270,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2016
End Date: 06-2020
Amount: $928,552.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2016
End Date: 12-2019
Amount: $325,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2007
End Date: 12-2010
Amount: $270,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2015
End Date: 12-2017
Amount: $355,100.00
Funder: Australian Research Council
View Funded ActivityStart Date: 02-2018
End Date: 12-2021
Amount: $344,192.00
Funder: Australian Research Council
View Funded ActivityStart Date: 02-2012
End Date: 12-2015
Amount: $370,000.00
Funder: Australian Research Council
View Funded Activity