ORCID Profile
0000-0001-8302-0370
Current Organisation
University of Tasmania
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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: 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: Wiley
Date: 12-10-2020
Publisher: Wiley
Date: 22-01-2018
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: Inter-Research Science Center
Date: 28-09-2012
DOI: 10.3354/MEPS09865
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: 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: Wiley
Date: 09-03-2021
DOI: 10.1111/ELE.13705
Abstract: Animals alter their habitat use in response to the energetic demands of movement (‘energy landscapes’) and the risk of predation (‘the landscape of fear’). Recent research suggests that animals also select habitats and move in ways that minimise their chance of temporarily losing control of movement and thereby suffering slips, falls, collisions or other accidents, particularly when the consequences are likely to be severe (resulting in injury or death). We propose that animals respond to the costs of an ‘accident landscape’ in conjunction with predation risk and energetic costs when deciding when, where, and how to move in their daily lives. We develop a novel theoretical framework describing how features of physical landscapes interact with animal size, morphology, and behaviour to affect the risk and severity of accidents, and predict how accident risk might interact with predation risk and energetic costs to dictate movement decisions across the physical landscape. Future research should focus on testing the hypotheses presented here for different real‐world systems to gain insight into the relative importance of theorised effects in the field.
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: 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.
No related grants have been discovered for Rebecca Wheatley.