ORCID Profile
0000-0003-1259-7898
Current Organisation
University of Western Australia
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Ecology | Behavioural Ecology | Life Histories | Population, Ecological and Evolutionary Genetics | Evolutionary Biology | Quantitative Genetics | Sociobiology And Behavioural Ecology | Ethology and Sociobiology | Animal Behaviour | Conservation and Biodiversity | Invertebrate Biology |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Biological Sciences | Biological sciences | Control of pests and exotic species | Flora, Fauna and Biodiversity of environments not elsewhere classified | Climate Change Mitigation Strategies | Plant Production and Plant Primary Products not elsewhere classified | Control of Plant Pests, Diseases and Exotic Species in Farmland, Arable Cropland and Permanent Cropland Environments | Disease Distribution and Transmission (incl. Surveillance and Response) | Forest and Woodlands Flora, Fauna and Biodiversity
Related Links
Publications
Sampling bias and fluctuating asymmetry
Publisher: Elsevier BV
Date: 06-1995
Is sexual selection defined by dimorphism alone? A reply to Padian and Horner
Publisher: Elsevier BV
Date: 05-2013
Positive size–speed relationships in gametes and vegetative cells of Chlamydomonas reinhardtii; implications for the evolution of sperm
Publisher: Wiley
Date: 03-2018
DOI: 10.1111/EVO.13427
Abstract: It is commonly held that differences in gametes of the two sexes (anisogamy) evolved from ancestors whose gametes were similar in size and behavior (isogamy). Underlying many hypotheses explaining anisogamy are assumed relationships between cell size and speed in the ancestral isogamous population. Using the isogamous alga Chlamydomonas reinhardtii, we explored size-speed distributions in vegetative and gamete cells of 10 cell lines, and clonal data from within two cell lines. We applied an independent speed selection approach to gamete populations of C. reinhardtii, monitoring correlated responses in size following selection for high speed. We demonstrate positive size-speed relationships in clones, cell lines, and artificially selected speed selection lines. We found different size-speed relationships in the two cell types of C. reinhardtii even though they overlap in size, suggesting that cell composition and/or programs of gene expression are capable of altering this relationship, and that the relationship is evolvable. The positive genetic size-speed correlation means that the ision of parent vegetative cells into numerous gametes trades off against not only size, but also speed, a trade-off that has not received previous attention. Our results support reevaluating the role of speed selection in the evolution of anisogamy.
Demographics of polycystic kidney disease and captive population viability in pygmy hippopotamus (Choeropsis liberiensis)
Publisher: Wiley
Date: 15-02-2017
DOI: 10.1002/ZOO.21351
Abstract: Polycystic kidney disease (PKD) was previously diagnosed at necropsy in several pygmy hippopotami (Choeropsis liberiensis) from the Smithsonian National Zoo and Zoo Basel, suggesting a threat to the long-term viability of the captive population. We determined the incidence and demographics of PKD in the captive population historically we tested if the condition is linked to pedigree we investigated mode of inheritance we examined effects of PKD on longevity we conducted survival analysis and we examined long-term population viability. Thirty-seven percent of 149 necropsied adult pygmy hippos were affected by PKD, and it was more common in females, controlling for the overall female-biased sex-ratio. Prevalence increased significantly with age, but most hippos were beyond their reproductive prime before developing clinical signs thus fecundity was likely unaffected. PKD was linked to pedigree and may exhibit X-linked dominance, but further research is needed to definitively establish the mode of inheritance. PKD did not affect longevity, overall or within any age class. There was no significant correlation between inbreeding coefficient (F) and PKD, and the prevalence in wild-caught and captive-born animals was similar. Longevity for both captive-born and inbred hippos (F > 0) was significantly shorter than longevity for their wild-caught and non-inbred counterparts. Demographic projections indicated the extant population will likely experience a slow increase over time, provided there are no space constraints. We conclude that although PKD is an important cause of morbidity and mortality in pygmy hippos, the condition is not a primary concern for overall viability of the captive population.
Developmental instability as phenodeviance in a secondary sexual trait increases sharply with thermal stress
Publisher: Wiley
Date: 23-11-2012
DOI: 10.1111/J.1420-9101.2011.02429.X
Abstract: We test for effects of thermal stress applied to pupal flies from Noumea (New Caledonia) and Taipei (Taiwan) on developmental instability (DI) in the male sex comb of Drosophila bipectinata, as well as on pre-adult survivorship and adult body size. The temperature treatments were Low (25 °C), High (29 °C) and Variable (18 h at 29 °C, 6 h at 34 °C). Although the Variable treatment reduced survivorship and body size, absolute comb size and fluctuating asymmetry generally were invariant across treatments. In contrast, comb phenodeviance increased with stress in both populations. Phenodeviance in one comb segment (C2) increased sharply with stress, whereas phenodeviance in a second major segment (C1) also increased with stress but only in Noumea flies. A major conclusion is that phenodeviations induced in a secondary sexual trait reflect the developmental environment that also damages fitness components, a foundation stone of the hypothesis that expressions of DI reveal phenotypic quality in sexual selection.
Quantifying variation in female internal genitalia: no evidence for plasticity in response to sexual conflict risk in a seed beetle
Publisher: The Royal Society
Date: 07-07-2021
Abstract: Sexually antagonistic coevolution can drive the evolution of male traits that harm females, and female resistance to those traits. While males have been found to vary their harmfulness to females in response to social cues, plasticity in female resistance traits remains to be examined. Here, we ask whether female seed beetles Callosobruchus maculatus are capable of adjusting their resistance to male harm in response to the social environment. Among seed beetles, male genital spines harm females during copulation and females might resist male harm via thickening of the reproductive tract walls. We develop a novel micro computed tomography imaging technique to quantify female reproductive tract thickness in three-dimensional space, and compared the reproductive tracts of females from populations that had evolved under high and low levels of sexual conflict, and for females reared under a social environment that predicted either high or low levels of sexual conflict. We find little evidence to suggest that females can adjust the thickness of their reproductive tracts in response to the social environment. Neither did evolutionary history affect reproductive tract thickness. Nevertheless, our novel methodology was capable of quantifying fine-scale differences in the internal reproductive tracts of in idual females, and will allow future investigations into the internal organs of insects and other animals.
Genic capture and resolving the lek paradox
Publisher: Elsevier BV
Date: 06-2004
DOI: 10.1016/J.TREE.2004.03.029
Abstract: The genic capture hypothesis offers a resolution to the question of how genetic variation in male sexually selected traits is maintained in the face of strong female preferences. The hypothesis is that male display traits are costly to produce and hence depend upon overall condition, which itself is dependent upon genes at many loci. Few attempts have been made to test the assumptions and predictions of the genic capture hypothesis rigorously and, in particular, little attention has been paid to determining the genetic basis of condition. Such tests are crucial to our understanding of the maintenance of genetic variation and in the evaluation of recent models that propose a role for sexual selection in the maintenance of sex. Here, we review approaches to testing the link between genetically determined condition and levels of sexual trait expression and consider the probable importance of deleterious mutations.
Sociosexual environment influences patterns of ejaculate transfer andfemale kicking in Callosobruchus maculatus
Publisher: Elsevier BV
Date: 08-2014
The limits of elaboration: Curved allometries reveal the constraints on mandible size in stag beetles
Publisher: The Royal Society
Date: 07-03-2004
Environmental and genetic determinants of the male forceps length dimorphism in the European earwig Forficula auricularia L.
Publisher: Springer Science and Business Media LLC
Date: 03-12-1999
Status‐dependence and morphological trade‐offs in the expression of a sexually selected character in the mite, Sancassania berlesei
Publisher: Wiley
Date: 21-08-2002
Publication bias in meta‐analysis: seeing the wood for the trees
Publisher: Wiley
Date: 2004
Males Influence Maternal Effects That Promote Sexual Selection: A Quantitative Genetic Experiment with Dung BeetlesOnthophagus taurus
Publisher: University of Chicago Press
Date: 06-2003
DOI: 10.1086/375173
Abstract: Recently, doubt has been cast on studies supporting good genes sexual selection by the suggestion that observed genetic benefits for offspring may be confounded by differential maternal allocation. In traditional analyses, observed genetic sire effects on offspring phenotype may result from females allocating more resources to the offspring of attractive males. However, maternal effects such as differential allocation may represent a mechanism promoting genetic sire effects, rather than an alternative to them. Here we report results from an experiment on the horned dung beetle Onthophagus taurus, in which we directly compare genetic sire effects with maternal effects that are dependent on sire phenotype. We found strong evidence that mothers provide more resources to offspring when mated with large-horned males. There were significant heritabilities for both horn length and body size, but when differential maternal effects were controlled, the observed estimates of genetic variance were greatly reduced. Our experiment provides evidence that differential maternal effects may lify genetic effects on offspring traits that are closely related to fitness. Thus, our results may partly explain the relatively high coefficients of additive genetic variation observed in fitness-related traits and provide empirical support for the theoretical argument that maternal effects can play an important role in evolution.
A theoretical muddle of the conditional strategy: a comment on Neff and Svensson
Publisher: The Royal Society
Date: 19-05-2014
Identification of seminal proteins related to the inhibition of mate searching in female crickets
Publisher: Oxford University Press (OUP)
Date: 19-10-2020
Abstract: In response to the reduction in fitness associated with sperm competition, males are expected to evolve tactics that hinder female remating. For ex le, females often display a postmating reduction in their sexual receptivity that has been shown to be mediated by proteins contained in a male’s seminal fluid (sfps). However, although there has been comprehensive research on sfps in genetically well-characterized species, few nonmodel species have been studied in such detail. We initially confirm that female Australian field crickets, Teleogryllus oceanicus, do display a significant reduction in their mate-searching behavior 24 h after mating. This effect was still apparent 3 days after mating but was entirely absent after 1 week. We then attempted to identify the sfps that might play a role in inducing this behavioral response. We identified two proteins, ToSfp022 and ToSfp011, that were associated with the alteration in female postmating behavior. The knockdown of both proteins resulted in mated females that displayed a significant increase in their mate-searching behaviors compared with females mated to males having the full compliment of seminal fluid proteins in their ejaculate. Our results indicate that the female refractory period in T. oceanicus likely reflects a sperm competition avoidance tactic by males, achieved through the action of male seminal fluid proteins.
Correlated responses to selection for different cell size in Chlamydomonas reinhardtii using divergent evolutionary pathways
Publisher: Springer Science and Business Media LLC
Date: 18-05-2023
DOI: 10.1007/S10811-023-02978-1
Abstract: Cell size is an important trait that is often correlated with organisms’ survival under different thermal environments, and in the case of phytoplankton, it is also related to survival under different light irradiance. While smaller phytoplankton thrive under warm and high light (summer conditions), larger cells seem to be more efficient under cool and low light conditions (winter conditions). In this study, we used different evolutionary pathways, nitrogen depletion and size selection, to select for differences in average cell diameter in the single-celled alga Chlamydomonas reinhardtii. We tested whether there was a size-related fitness (growth rate) advantage across two light intensities and two temperatures environmental effects that have dramatic effects on algal growth. Under these environmental conditions we then tested how the evolutionary pathway to reduced cell size affected fitness and photophysiology. The results suggest that the relationship between size and growth rate in C. reinhardtii is strongly correlated with changes in the photosynthetic apparatus in different sized cells. Large-selected cells evolved to have smaller light-harvesting antennae, making them less susceptible to photodamage. However, they accumulate larger amounts of reactive oxygen species, potentially due to their lack of antioxidant carotenoids. In addition, the maximum growth rate was reduced, potentially due to their reduced ability to repair PSII due to lower metabolic rates. Similar responses were observed in lines that evolved to have smaller cells under nitrogen depletion. The results demonstrate that different evolutionary pathways to reduced cell size result in different changes in metabolism, with N-depleted and Small-selected cell lineages having similar sizes, but thriving differently under winter/summer conditions. With large production systems in mind, it is possible to assume that the choice of strains selected using adaptative laboratory evolution or direct selection on size can affect the overall production yield and carbon capture according to the seasons and possibly other abiotic parameters.
The discrimination of alternative male morphologies
Publisher: Oxford University Press (OUP)
Date: 09-2001
Towards a resolution of the lek paradox
Publisher: Springer Science and Business Media LLC
Date: 04-2001
DOI: 10.1038/35070557
An age-dependent ovulatory strategy explains the evolution of dizygotic twinning in humans
Publisher: Springer Science and Business Media LLC
Date: 11-05-2020
Dung pad residence time covaries with male morphology in the dung beetle Onthophagus taurus
Publisher: Wiley
Date: 05-1999
Brood-provisioning strategies in Dawson's burrowing bee, Amegilla dawsoni (Hymenoptera: Anthophorini)
Publisher: Springer Science and Business Media LLC
Date: 06-06-2001
Improved biomass production of a microalga through adaptative laboratory evolution to a high light environment
Publisher: Springer Science and Business Media LLC
Date: 17-03-2023
Heat stress but not inbreeding affects offensive sperm competitiveness in Callosobruchus maculatus
Publisher: Wiley
Date: 24-07-2013
DOI: 10.1002/ECE3.667
Experimental evidence for accelerated adaptation to desiccation through sexual selection on males
Publisher: Wiley
Date: 25-05-2020
DOI: 10.1111/JEB.13634
Phylogeography and Population Genetic Structure of the Ornate Dragon Lizard, Ctenophorus ornatus
Publisher: Public Library of Science (PLoS)
Date: 10-2012
Female Callosobruchus maculatus can maximize long-term fitness through polyandry
Publisher: Oxford University Press (OUP)
Date: 15-12-2015
Comparing evolvabilities: Common errors surrounding the calculation and use of coefficients of additive genetic variation
Publisher: Wiley
Date: 06-02-2012
DOI: 10.1111/J.1558-5646.2011.01565.X
Abstract: In 1992, David Houle showed that measures of additive genetic variation standardized by the trait mean, CVA (the coefficient of additive genetic variation) and its square (IA), are suitable measures of evolvability. CVA has been used widely to compare patterns of genetic variation. However, the use of CVAs for comparative purposes relies critically on the correct calculation of this parameter. We reviewed a s le of quantitative genetic studies, focusing on sire models, and found that 45% of studies use incorrect methods for calculating CVA and that practices that render these coefficients meaningless are frequent. This may have important consequences for conclusions drawn from comparative studies. Our results are suggestive of a broader problem because miscalculation of the additive genetic variance from a sire model is prevalent among the studies s led, implying that other important quantitative genetic parameters might also often be estimated incorrectly. We discuss the most prominent issues affecting the use of CVA and IA, including scale effects, data transformation, and the comparison of traits with different dimensions. Our aim is to increase awareness of the potential mistakes surrounding the calculation and use of evolvabilities, and to compile general guidelines for calculating, reporting, and interpreting these useful measures in future studies.
Male responses to sperm competition when rivals vary in number and familiarity
Publisher: The Royal Society
Date: 30-01-2019
Abstract: Males of many species adjust their reproductive investment to the number of rivals present simultaneously. However, few studies have investigated whether males sum previous encounters with rivals, and the total level of competition has never been explicitly separated from social familiarity. Social familiarity can be an important component of kin recognition and has been suggested as a cue that males use to avoid harming females when competing with relatives. Previous work has succeeded in independently manipulating social familiarity and relatedness among rivals, but experimental manipulations of familiarity are confounded with manipulations of the total number of rivals that males encounter. Using the seed beetle Callosobruchus maculatus , we manipulated three factors: familiarity among rival males, the maximum number of rivals encountered simultaneously and the total number of rivals encountered over a 48 h period. Males produced smaller ejaculates when exposed to more rivals in total, regardless of the maximum number of rivals they encountered simultaneously. Males did not respond to familiarity. Our results demonstrate that males of this species can sum the number of rivals encountered over separate days, and therefore the confounding of familiarity with the total level of competition in previous studies should not be ignored.
Metabolic rate does not decrease with starvation in Gryllus bimaculatus when changing fuel use is taken into account
Publisher: Wiley
Date: 14-11-2010
Testing the status‐dependent ESS model: population variation in fighter expression in the mite Sancassania berlesei
Publisher: Wiley
Date: 31-08-2004
DOI: 10.1111/J.1420-9101.2004.00780.X
Abstract: The conditional evolutionarily stable strategy (ESS) with status-dependent tactics is the most commonly invoked ESS for alternative reproductive tactics within the sexes. Support for this model has recently been criticized as apparent rather than real. We address key predictions of the status-dependent ESS in three populations of the male dimorphic mite Sancassania berlesei. In S. berlesei'fighter' males are characterized by a thickened pair of legs used for killing rivals 'scramblers' are benign. Most males in each population could be manipulated to become fighters by decreasing density, fulfilling the prediction that males make a 'decision'. There was evidence of genetic covariance between sire status and offspring morph, but also a strong effect of sire morph on offspring morph ratio. This was consistent with considerable genetic variation for the status-dependent switch point as a breeding experiment found no support for single-locus inheritance. We also found evidence that switch points evolve independently of distributions of status. This study supports the current status-dependent ESS model.
Phenotypic plasticity in the developmental integration of morphological trade-offs and secondary sexual trait compensation
Publisher: The Royal Society
Date: 07-03-2005
Abstract: Trait exaggeration through sexual selection will take place alongside other changes in phenotype. Exaggerated morphology might be compensated by parallel changes in traits that support, enhance or facilitate exaggeration: ‘secondary sexual trait compensation’ (SSTC). Alternatively, exaggeration might be realized at the expense of other traits through morphological trade-offs. For the most part, SSTC has only been examined interspecifically. For these phenomena to be important intraspecifically, the sexual trait must be developmentally integrated with the compensatory or competing trait. We studied developmental integration in two species with different development: the holometabolous beetle Onthophagus taurus and the hemimetabolous earwig Forficula auricularia . Male-dimorphic variation in trait exaggeration was exploited to expose both trade-offs and SSTC. We found evidence for morphological trade-offs in O. taurus , but not F. auricularia , supporting the notion that trade-offs are more likely in closed developmental systems. However, we found these trade-offs were not limited solely to traits growing close together. Developmental integration of structures involved in SSTC were detected in both species. The developmental integration of SSTC was phenotypically plastic, such that the compensation for relatively larger sexual traits was greater in the exaggerated male morphs. Evidence of intraspecific SSTC demands studies of the selective, genetic and developmental architecture of phenotypic integration.
Habitat Complexity Drives Experimental Evolution of a Conditionally Expressed Secondary Sexual Trait
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.CUB.2011.02.032
Abstract: The conditional expression of alternative phenotypes underlies the production of almost all life history decisions and many dichotomous traits, including male alternative reproductive morphs and behavioral tactics. Changes in tactic fitness should lead to evolutionary shifts in developmental switch points that underlie tactic expression. We used experimental evolution to directly test this hypothesis by rearing ten generations of the male-dimorphic mite Rhizoglyphus echinopus in either simple or three-dimensionally complex habitats that differed in their effects on morph fitness. In R. echinopus, fighter males develop weapons used for killing rivals, whereas scrambler males do not. Populations evolving in complex 3D habitats, where fighters had reduced fitness, produced fewer fighters because the switch point for fighter development evolved to a larger critical body size. Both the reduced mobility of fighter males and the altered spatial distribution of potential mates and rivals in the complex habitat were implicated in the evolutionary ergence of switch point between the habitats. Our results demonstrate how abiotic factors like habitat complexity can have a profound effect on evolution through sexual selection.
STRUCTURAL COMPLEXITY OF THE ENVIRONMENT AFFECTS THE SURVIVAL OF ALTERNATIVE MALE REPRODUCTIVE TACTICS
Publisher: The Society for the Study of Evolution
Date: 2006
DOI: 10.1554/05-423.1
Land clearing reduces gene flow in the granite outcrop-dwelling lizard, Ctenophorus ornatus
Publisher: Wiley
Date: 11-09-2010
Molecular evidence supports a genic capture resolution of the lek paradox
Publisher: Springer Science and Business Media LLC
Date: 25-03-2019
DOI: 10.1038/S41467-019-09371-Y
Abstract: The genic capture hypothesis, where sexually selected traits capture genetic variation in condition and the condition reflects genome-wide mutation load, stands to explain the presence of abundant genetic variation underlying sexually selected traits. Here we test this hypothesis by applying bidirectional selection to male mating success for 14 generations in replicate populations of Drosophila melanogaster . We then resequenced the genomes of flies from each population. Consistent with the central predictions of the genic capture hypothesis, we show that genetic variance decreased with success selection and increased with failure selection, providing evidence for purifying sexual selection. This pattern was distributed across the genome and no consistent molecular pathways were associated with ergence, consistent with condition being the target of selection. Together, our results provide molecular evidence suggesting that strong sexual selection erodes genetic variation, and that genome-wide mutation-selection balance contributes to its maintenance.
SPERM COMPETITION GAMES BETWEEN SNEAKS AND GUARDS: A COMPARATIVE ANALYSIS USING DIMORPHIC MALE BEETLES
Publisher: Wiley
Date: 11-2007
DOI: 10.1111/J.1558-5646.2007.00243.X
Abstract: Sperm competition is widely recognized as a pervasive force of sexual selection. Theory predicts that across species increased risk of sperm competition should favor an increased expenditure on the ejaculate, a prediction for which there is much evidence. Sperm competition games have also been developed specifically for systems in which males adopt the alternative male mating tactics of sneaking copulations or guarding females. These models have not yet been tested in a comparative context, but predict that: across species male expenditure on the ejaculate should increase with increasing probability of a sneak mating within species, sneaks should have the greater expenditure on the ejaculate and the disparity in expenditure between sneaks and guards should be greatest in species with moderate risk of a sneak mating, and decline toward parity in species with low or high risk. Beetles in the genus Onthophagus are often characterized by dimorphic male morphologies that reflect the alternative mating tactics of sneak (minor males) and guard (major males). We conducted a comparative analysis across 16 species of male dimorphic onthophagines, finding that testes size increased across species with increasing frequency of the minor male phenotype. Minor males generally had the greater testes size, but across species the disparity between morphs was independent of the frequency of minor males. We present data on testes allometry from two populations of O. taurus that have undergone genetic ergence in the frequency of minor males. Consistent with the comparative analysis, these data support the notion that the relative frequency of sneaks in the population influences male expenditure on the ejaculate.
Sperm competition games played by dimorphic male beetles
Publisher: The Royal Society
Date: 22-01-1999
Dimorphisms and fluctuating asymmetry in the forceps of male earwigs
Publisher: Wiley
Date: 11-1996
Positive Allometry and the Prehistory of Sexual Selection
Publisher: University of Chicago Press
Date: 08-2010
DOI: 10.1086/653001
Abstract: The function of the exaggerated structures that adorn many fossil vertebrates remains largely unresolved. One recurrent hypothesis is that these elaborated traits had a role in thermoregulation. This orthodoxy persists despite the observation that traits exaggerated to the point of impracticality in extant organisms are almost invariably sexually selected. We use allometric scaling to investigate the role of sexual selection and thermoregulation in the evolution of exaggerated traits of the crested pterosaur Pteranodon longiceps and the sail-backed eupelycosaurs Dimetrodon and Edaphosaurus. The extraordinarily steep positive allometry of the head crest of Pteranodon rules out all of the current hypotheses for this trait's main function other than sexual signaling. We also find interspecific patterns of allometry and sexual dimorphism in the sails of Dimetrodon and patterns of elaboration in Edaphosaurus consistent with a sexually selected function. Furthermore, small ancestral, sail-backed pelycosaurs would have been too small to need adaptations to thermoregulation. Our results question the popular view that the elaborated structures of these fossil species evolved as thermoregulatory organs and provide evidence in support of the hypothesis that Pteranodon crests and eupelycosaur sails are among the earliest and most extreme ex les of elaborate sexual signals in the evolution of terrestrial vertebrates.
Among-individual variation in behaviour and its effect on reproductive success
Publisher: Elsevier BV
Date: 03-2023
Can minor males of Dawson's burrowing bee, Amegilla dawsoni (Hymenoptera: Anthophorini) compensate for reduced access to virgin females through sperm competition?
Publisher: Oxford University Press (OUP)
Date: 05-2000
Genetic variation underlying the expression of a polyphenism
Publisher: Wiley
Date: 22-02-2012
DOI: 10.1111/J.1420-9101.2012.02469.X
Abstract: Polyphenic traits are widespread and represent a conditional strategy sensitive to environmental cues. The environmentally cued threshold (ET) model considers the switchpoint between alternative phenotypes as a polygenic quantitative trait with normally distributed variation. However, the genetic variation for switchpoints has rarely been explored empirically. Here, we used inbred lines to investigate the genetic variation for the switchpoint in the mite Rhizoglyphus echinopus, in which males are either fighters or scramblers. The conditionality of male dimorphism varied among inbred lines, indicating that there was genetic variation for switchpoints in the base population, as predicted by the ET model. Our results also suggest a mixture between canalized and conditional strategists in R. echinopus. We propose that major genes that canalize morph expression and affect the extent to which a trait can be conditionally expressed could be a feature of the genetic architecture of threshold traits in other taxa.
Morph-specific artificial selection reveals a constraint on the evolution of polyphenisms
Publisher: The Royal Society
Date: 23-05-2018
Abstract: Theory predicts that the evolution of polyphenic variation is facilitated where morphs are genetically uncoupled and free to evolve towards their phenotypic optima. However, the assumption that developmentally plastic morphs can evolve independently has not been tested directly. Using morph-specific artificial selection, we investigated correlated evolution between the sexes and male morphs of the bulb mite Rhizoglyphus echinopus . Large ‘fighter’ males have a thick and sharply terminating pair of legs used to kill rival males, while small ‘scrambler’ males have unmodified legs, and search for unguarded females, avoiding fights. We selected on the relative leg width of only the fighter male morph, tracked the evolutionary responses in fighters and the correlated evolutionary responses in scramblers and females that were untouched by direct selection. Fighters erged in relative leg thickness after six generations assaying scramblers and females at the ninth generation we observed correlated responses in relative leg width in both. Our results represent strong evidence for the evolution of intraspecific phenotypic ersity despite correlated evolution between morphs and sexes, challenging the idea that male morphs are genetically uncoupled and free to independently respond to selection. We therefore question the perceived necessity for genetic independence in traits with extreme phenotypic plasticity.
It's not all black and white: Investigating colour polymorphism in manta rays across Indo-Pacific populations
Publisher: The Royal Society
Date: 09-10-2019
Abstract: Intraspecific colour polymorphisms have been the focus of numerous studies, yet processes affecting melanism in the marine environment remain poorly understood. Arguably, the most prominent ex le of melanism in marine species occurs in manta rays ( Mobula birostris and Mobula alfredi ). Here, we use long-term photo identification catalogues to document the frequency variation of melanism across Indo-Pacific manta ray populations and test for evidence of selection by predation acting on colour morph variants. We use mark–recapture modelling to compare survivorship of typical and melanistic colour morphs in three M. alfredi populations and assess the relationship between frequency variation and geographical distance . While there were large differences in melanism frequencies among populations of both species (0–40.70%), apparent survival estimates revealed no difference in survivorship between colour morphs. We found a significant association between phenotypic and geographical distance in M. birostris , but not in M. alfredi . Our results suggest that melanism is not under selection by predation in the tested M. alfredi populations, and that frequency differences across populations of both species are a consequence of neutral genetic processes . As genetic colour polymorphisms are often subjected to complex selection mechanisms, our findings only begin to elucidate the underlying evolutionary processes responsible for the maintenance and frequency variation of melanism in manta ray populations.
Towards an evolutionary understanding of questing behaviour in the tick Ixodes ricinus
Publisher: Public Library of Science (PLoS)
Date: 15-10-2014
Investigating the genetic architecture of conditional strategies using the environmental threshold model
Publisher: The Royal Society
Date: 22-12-2015
Abstract: The threshold expression of dichotomous phenotypes that are environmentally cued or induced comprise the vast majority of phenotypic dimorphisms in colour, morphology, behaviour and life history. Modelled as conditional strategies under the framework of evolutionary game theory, the quantitative genetic basis of these traits is a challenge to estimate. The challenge exists firstly because the phenotypic expression of the trait is dichotomous and secondly because the apparent environmental cue is separate from the biological signal pathway that induces the switch between phenotypes. It is the cryptic variation underlying the translation of cue to phenotype that we address here. With a ‘half-sib common environment’ and a ‘family-level split environment’ experiment, we examine the environmental and genetic influences that underlie male dimorphism in the earwig Forficula auricularia . From the conceptual framework of the latent environmental threshold (LET) model, we use pedigree information to dissect the genetic architecture of the threshold expression of forceps length. We investigate for the first time the strength of the correlation between observable and cryptic ‘proximate’ cues. Furthermore, in support of the environmental threshold model, we found no evidence for a genetic correlation between cue and the threshold between phenotypes. Our results show strong correlations between observable and proximate cues and less genetic variation for thresholds than previous studies have suggested. We discuss the importance of generating better estimates of the genetic variation for thresholds when investigating the genetic architecture and heritability of threshold traits. By investigating genetic architecture by means of the LET model, our study supports several key evolutionary ideas related to conditional strategies and improves our understanding of environmentally cued decisions.
How sperm competition shapes the evolution of testes and sperm: a meta-analysis
Publisher: The Royal Society
Date: 19-10-2020
Abstract: Females of many species mate with multiple males, thereby inciting competition among ejaculates from rival males for fertilization. In response to increasing sperm competition, males are predicted to enhance their investment in sperm production. This prediction is so widespread that testes size (correcting for body size) is commonly used as a proxy of sperm competition, even in the absence of any other information about a species' reproductive behaviour. By contrast, a debate about whether sperm competition selects for smaller or larger sperm has persisted for nearly three decades, with empirical studies demonstrating every possible response. Here, we synthesize nearly 40 years of sperm competition research in a meta-analytical framework to determine how the evolution of sperm number (i.e. testes size) and sperm size (i.e. sperm head, midpiece, flagellum and total length) is influenced by varying levels of sperm competition across species. Our findings support the long-held assumption that higher levels of sperm competition are associated with relatively larger testes. We also find clear evidence that sperm competition is associated with increases in all components of sperm length. We discuss these results in the context of different theoretical predictions and general patterns in the breeding biology and selective environment of sperm. This article is part of the theme issue ‘Fifty years of sperm competition’.
Translocation precipitates natural hybridisation and pervasive introgression between marine gastropods with divergent developmental modes
Publisher: Elsevier BV
Date: 07-2023
Mixed evidence for the erosion of intertactical genetic correlations through intralocus tactical conflict
Publisher: Wiley
Date: 11-05-2017
DOI: 10.1111/JEB.13093
Abstract: Alternative reproductive tactics, whereby members of the same sex use different tactics to secure matings, are often associated with conditional intrasexual dimorphisms. Given the different selective pressures on males adopting each mating tactic, intrasexual dimorphism is more likely to arise if phenotypes are genetically uncoupled and free to evolve towards their phenotypic optima. However, in this context, genetic correlations between male morphs could result in intralocus tactical conflict (ITC). We investigated the genetic architecture of male dimorphism in bulb mites (Rhizoglyphus echinopus) and earwigs (Forficula auricularia). We used half-sibling breeding designs to assess the heritability and intra/intersexual genetic correlations of dimorphic and monomorphic traits in each species. We found two contrasting patterns F. auricularia exhibited low intrasexual genetic correlations for the dimorphic trait, suggesting that the ITC is moving towards a resolution. Meanwhile, R. echinopus exhibited high and significant intrasexual genetic correlations for most traits, suggesting that morphs in the bulb mite may be limited in evolving to their optima. This also shows that intrasexual dimorphisms can evolve despite strong genetic constraints, contrary to current predictions. We discuss the implications of this genetic constraint and emphasize the potential importance of ITC for our understanding of intrasexual dimorphisms.
Maternal effects on male weaponry
Publisher: Springer Science and Business Media LLC
Date: 2012
Population density drives the local evolution of a threshold dimorphism
Publisher: Springer Science and Business Media LLC
Date: 10-2004
DOI: 10.1038/NATURE02918
Abstract: Evolution can favour more than one reproductive tactic among conspecifics of the same sex. Under the conditional evolutionarily stable strategy, in iduals adopt the tactic that generates the highest fitness return for their status: large males guard females, whereas small males sneak copulations. Tactics change at the status at which fitness benefits switch from favouring one tactic to favouring the alternative. This 'switchpoint' is expressed in many species as a threshold between ergent morphologies. Environmental and demographic parameters that influence the relative fitness of male tactics are predicted to determine a population's switchpoint and consequently whether the population is monomorphic or dimorphic. Here we show threshold evolution in the forceps dimorphism of the European earwig Forficula auricularia and document the transition from completely monomorphic to classical male-dimorphic populations over a distance of only 40 km. Because the superior fighting ability of the dominant morph will be more frequently rewarded at high encounter rates, population density is likely to be a key determinant of the relative fitness of the alternative tactics, and consequently the threshold. We show that, as predicted, population density correlates strongly with the shift in threshold, and that this factor drives the local evolution of the male dimorphism in these island populations. Our data provide evidence for the origin of phenotypic ersity within populations, through the evolution of a switchpoint in a conditional strategy that has responded to local population density.
Sex-specific pace-of-life syndromes
Publisher: Oxford University Press (OUP)
Date: 25-04-2019
Abstract: The pace-of-life syndrome (POLS) hypothesis considers an animal’s behavior, physiology, and life history as nonindependent components of a single integrated phenotype. However, frequent deviations from the expected correlations between POLS traits suggest that these relationships may be context, and potentially, sex dependent. To determine whether the sexes express distinct POLS trait covariance structures, we observed the behavior (mobility, latency to emerge from a shelter), physiology (mass-specific metabolic rate), and life history (life span, development time) of male and female Australian field crickets (Teleogryllus oceanicus). Path analysis modeling suggested that POLS trait covariation differed between the sexes. Although neither sex displayed the complete integration of traits predicted by the POLS hypothesis, females did display greater overall integration with a significant negative correlation between metabolic rate and risk-taking behavior but with life-history traits varying independently. In males, however, there was no clear association between traits. These results suggest that T. oceanicus do indeed display sex-specific trait covariance structures, emphasizing the importance of acknowledging sex in assessments of POLS.
Measuring relative investment: a case study of testes investment in species with alternative male reproductive tactics
Publisher: Elsevier BV
Date: 05-2002
The role of genes and environment in the phenotypic expression of alternative mating tactics: a reply to Buzatto et al.
Publisher: The Royal Society
Date: 19-05-2014
Nongenetic inheritance of behavioural variability is context specific and sex specific
Publisher: Wiley
Date: 08-10-2021
Abstract: Environmentally mediated nongenetic inheritance extends the concept of phenotypic plasticity across generations, allowing for the experience of parents to influence the physiology, life history and behaviour of their offspring. We assess whether the perceived social environment of mothers and fathers impacts offspring behaviour in the Australian field cricket Teleogryllus oceanicus . We varied parents' perception of the density of conspecific males by exposing parents to either the presence or absence of male song throughout rearing. Following mating in a factorial design, the offspring of the parental pairs were also reared across the two acoustic environments and their behaviour assessed as adults. When reared in a no‐song environment, offspring of both sexes were more active, emerging from a shelter sooner and displaying greater mobility in search of male song. Offspring behaviour was not directly impacted by either the maternal or paternal social environments independently, but there was a significant interaction effect between the parental environments on the behaviour of daughters. When both parents were reared in song (‘paternal song × maternal song’), their no‐song‐reared daughters exhibited lower levels of mobility than the no‐song‐reared daughters of ‘paternal song × maternal no‐song’ and ‘paternal no‐song × maternal song’ pairs. Although our data suggest that nongenetic parental effects may have the potential to drive behavioural variability in offspring, such effects are highly complex, only arising as sex‐ and context‐specific traits. A free Plain Language Summary can be found within the Supporting Information of this article.
Sexual selection and the allometry of earwig forceps
Publisher: Springer Science and Business Media LLC
Date: 1996
DOI: 10.1007/BF01239350
Males adjust their manipulation of female remating in response to sperm competition risk
Publisher: The Royal Society
Date: 02-09-2020
Abstract: To reduce the potential for sperm competition, male insects are thought to inhibit the post-mating reproductive behaviour of females through receptivity-inhibiting compounds transferred in the ejaculate. Selection is expected to favour phenotypic plasticity in male post-copulatory expenditure, with males investing strategically in response to their perceived risk of sperm competition. However, the impact that socially cued strategic allocation might have on female post-mating behaviour has rarely been assessed. Here, we varied male perception of sperm competition risk, both prior to and during mating, to determine if a male's competitive environment impacts the extent to which he manipulates female remating behaviour. We found that female Australian field crickets ( Teleogryllus oceanicus ) mated to males that were reared under sperm competition risk emerged from a shelter in search of male song sooner than did females mated to males reared without risk, but only when mating occurred in a risk-free environment. We also found that females reared in a silent environment where potential mates were scarce emerged from the shelter sooner than females exposed to male calls during development. Collectively, our findings suggest complex interacting effects of male and female sociosexual environments on female post-mating sexual receptivity.
Sex ratio bias in the dung beetle Onthophagus taurus: adaptive allocation or sex-specific offspring mortality?
Publisher: Springer Science and Business Media LLC
Date: 03-09-2010
Sperm competition games played by dimorphic male beetles: fertilization gains with equal mating access
Publisher: The Royal Society
Date: 07-08-2000
State-dependent changes in risk-taking behaviour as a result of age and residual reproductive value
Publisher: Elsevier BV
Date: 08-2018
Fitness consequences of threshold trait expression subject to environmental cues
Publisher: The Royal Society
Date: 27-06-2018
Abstract: Most cases of alternative reproductive tactics (ARTs) are thought to represent conditional strategies, whereby high-status males express highly competitive phenotypes, whereas males below a certain status threshold resort to sneaky tactics. The underlying evolutionarily stable strategy (ESS) model assumes that males of high competitive ability achieve higher fitness when expressing the territorial phenotype, whereas the less competitive males are more fit as sneakers, caused by fitness functions for the ARTs having different slopes and intersecting at a threshold value of competitive ability. The model, however, is notoriously difficult to test as it requires access to low-status territorials and high-status sneakers, that rarely occur in nature. Here, we test the conditional ESS in the androdimorphic acarid mite Sancassania berlesei , where large males tend to develop into an armoured, aggressive ‘fighter’ morph, while small males become unarmoured, non-aggressive ‘scramblers’. In addition to body size, male morph is affected by pheromones produced by big populations, with fighters being suppressed in dense colonies. By manipulating pheromone concentration, we obtained high-status scramblers and low-status fighters. We also estimated status- and size-dependent fitness functions for male morphs across a range of population sizes. Fighters had the highest fitness in small populations and their fitness declined with increasing density, whereas the reverse was true for scramblers, providing support for condition-dependent ESS with respect to demography. However, whereas male fitness increased with body size, the fitness functions did not differ significantly between morphs. Thus, although we found evidence for the intersection of morph fitness functions with respect to demography, we did not find such an intersection in relation to male body size. Our results highlight how demography can exert selection pressures shaping the evolution of the conditional strategy in species with ARTs.
Evolutionary divergence in competitive mating success through female mating bias for good genes
Publisher: American Association for the Advancement of Science (AAAS)
Date: 04-05-2018
Abstract: Evolutionary ergence in competitive male mating success correlates with the load of deleterious recessive mutations.
Heritability of size but not symmetry in a sexually selected trait chosen by female earwigs
Publisher: Springer Science and Business Media LLC
Date: 02-1999
Explaining Phenotypic Diversity: The Conditional Strategy and Threshold Trait Expression
Publisher: Wiley
Date: 08-04-2011
Additive genetic breeding values correlate with the load of partially deleterious mutations
Publisher: American Association for the Advancement of Science (AAAS)
Date: 14-05-2010
Abstract: The phenotype of an organism is related to its additive genetic phenotype, the small but numerous genetic differences between in iduals affecting their phenotype, and its mutational load, which is the number of mutations an in idual carries. How these two factors affect an in idual's ability to leave offspring in the next generation is a major component of evolutionary theory, but evidence for a direct relationship has been lacking. By estimating the contribution of partially recessive mutations to additive genetic variation in seed-feeding cow-pea weevils over a seven-generation pedigree breeding program involving variation in levels of inbreeding, Tomkins et al. (p. 892 ) demonstrate an association between genetic quality and the mutational load carried, especially for males.
On the resolution of the lek paradox
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/J.TREE.2007.09.012
Abstract: Directional female mate choice is expected to deplete additive genetic variation in male traits. This should preclude such trait-based choice from resulting in genetic benefits to offspring, and yet genetic benefits are the explanation for the choice. This evolutionary conundrum is known as the lek paradox. Newly proposed resolutions to this paradox aim to unravel mechanisms that contribute to the persistence of genetic variance in traits under directional female mate choice.
Cell size selection in Chlamydomonas reinhardtii gametes using fluorescence activated cell sorting
Publisher: Elsevier BV
Date: 06-2016
Major Differences in Minor Allometries: A Reply to Moczek
Publisher: University of Chicago Press
Date: 04-2006
DOI: 10.1086/501077
Abstract: By comparing alternative measurements of horn length in the beetle Onthophagus taurus, we have investigated why scaling patterns differ between laboratories. We show that some measurements are confounded by including part of the head in the horn size measurement and consistently underestimate the allometry of horns in minor males. Our data show how linear measures that avoid confounding horn length with head size produce scaling patterns that support a positive allometry rather than a reprogramming model of horn growth. We also found horn volume was highly positively allometric this estimate of growth therefore further supports a positive allometry model.
Fluctuating paradigm
Publisher: The Royal Society
Date: 22-03-1999
Male semelparity and multiple paternity confirmed in an arid‐zone dasyurid
Publisher: Wiley
Date: 21-04-2019
DOI: 10.1111/JZO.12672
Intralocus tactical conflict
Publisher: Wiley
Date: 03-2015
DOI: 10.1111/JEB.12598
Abstract: Males and females differ in their phenotypic optima for many traits, and as the majority of genes are expressed in both sexes, some alleles can be beneficial to one sex but harmful to the other (intralocus sexual conflict ISC). ISC theory has recently been extended to intrasexual dimorphisms, where certain alleles may have opposite effects on the fitness of males of different morphs that employ alternative reproductive tactics (intralocus tactical conflict ITC). Here, we use a half-sib breeding design to investigate the genetic basis for ISC and ITC in the dung beetle Onthophagus taurus. We found positive heritabilities and intersexual genetic correlations for almost all traits investigated. Next, we calculated the intrasexual genetic correlation between males of different morphs for horn length, a sexually selected trait, and compared it to intrasexual correlations for naturally selected traits in both sexes. Intrasexual genetic correlations did not differ significantly between the sexes or between naturally and sexually selected traits, failing to support the hypothesis that horns present a reduction of intrasexual genetic correlations due to ITC. We discuss the implications for the idea of developmental reprogramming between male morphs and emphasize the importance of genetic correlations as constraints for the evolution of dimorphisms.
Patterns of fluctuating asymmetry in earwig forceps: no evidence for reliable signalling
Publisher: The Royal Society
Date: 23-01-1995
Experience counts: lessons from studies of differential allocation
Publisher: Oxford University Press (OUP)
Date: 22-06-2005
The effects of the social environment and physical disturbance on personality traits
Publisher: Elsevier BV
Date: 04-2018
Matters of Scale: Positive Allometry and the Evolution of Male Dimorphisms
Publisher: University of Chicago Press
Date: 03-2005
DOI: 10.1086/427732
Abstract: The developmental independence of alternative phenotypes is key to evolutionary theories of phenotypic plasticity and the origins of ersity. Male dimorphisms associated with alternative reproductive tactics are widely cited ex les of such facultative expression of ergent fitness optima. Current models for the evolution of male dimorphisms invoke a size-dependent threshold at which the phenotype is reprogrammed. We use predictions derived from allometric modeling to test for the existence of reprogramming thresholds in two species of beetle, Onthophagus taurus and Onthophagus binodis, and the European earwig Forficula auricularia. We also compare the allometry of a number of morphological traits to determine whether minor males suppress their secondary sexual traits. The intercept of the horn allometry was suppressed, but there was no evidence of reprogramming of horn growth in either beetle species. There was reprogramming in the earwig. In the beetles, the horn length in all males can be explained largely in terms of exponential horn growth following an extraordinarily steep power function. The asymptote in O. taurus can be explained by exponential growth meeting the constraint of resource exhaustion. These findings question the currently held view that beetle horn dimorphisms showcase the importance of developmental independence in the evolution of ersity.
Genome-wide SNPs detect no evidence of genetic population structure for reef manta rays (Mobula alfredi) in southern Mozambique
Publisher: Springer Science and Business Media LLC
Date: 10-2021
The status of the conditional evolutionarily stable strategy
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.TREE.2007.09.002
Abstract: The conditional evolutionarily stable strategy (ESS) has proven to be a versatile tool for understanding the production of alternative phenotypes in response to environmental cues. Hence, we would expect the theoretical basis of the conditional strategy to be robust. However, Shuster and Wade have recently criticized the conditional ESS based on Gross's 1996 proposal that most alternative reproductive tactics are conditional and have evolved by 'status-dependent selection.' We critically assess Gross's status-dependent selection model and Shuster and Wade's critique. We find shortcomings and misconceptions in both. We return to the findings of the strategic models behind the conditional ESS and demonstrate how environmental threshold models use a reaction norm approach and quantitative genetic theory to understand the evolution of conditional strategies.
Correlates of ball size and rolling speed in the dung beetle Kheper nigroaeneus (Coleoptera: Scarabaeidae)
Publisher: Wiley
Date: 08-1999
Sexual selection in prehistoric animals: detection and implications
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.TREE.2012.07.015
Abstract: Many fossil animals bear traits such as crests or horns that probably functioned as sexually selected signals or weapons. Interpretations of these structures as functioning in mate choice or intrasexual contests are often controversial, with interpretations based on biomechanics or physiology being favoured by many. Although testing hypotheses based on sexual selection can be difficult, especially given that there is no single, reliable means of recognising sexual selection, we argue that it is not impossible indeed, there are now several cases where sexual selection is strongly supported. In other cases, a careful study of features such as sexual dimorphism, ontogeny, and allometry, coupled with testing of alternative hypotheses, will be necessary to distinguish between possible explanations for exaggerated features.
Countering counteradaptations: Males hijack control of female kicking behavior
Publisher: Oxford University Press (OUP)
Date: 17-03-2014
Alternative phenotypes and sexual selection: can dichotomous handicaps honestly signal quality?
Publisher: The Royal Society
Date: 07-07-2004
Structural complexity of the environment affects the survival of alternative male reproductive tactics
Publisher: Wiley
Date: 02-2006
Correlated evolution of sexual dimorphism and male dimorphism in a clade of neotropical harvestmen
Publisher: Wiley
Date: 09-04-2014
DOI: 10.1111/EVO.12395
Abstract: Secondary sexual traits increase male fitness, but may be maladaptive in females, generating intralocus sexual conflict that is ameliorated through sexual dimorphism. Sexual selection on males may also lead some males to avoid expenditure on secondary sexual traits and achieve copulations using alternative reproductive tactics (ARTs). Secondary sexual traits can increase or decrease fitness in males, depending on which ART they employ, generating intralocus tactical conflict that can be ameliorated through male dimorphism. Due to the evolutionary forces acting against intralocus sexual and tactical conflicts, male dimorphism could coevolve with sexual dimorphism, a hypothesis that we tested by investigating these dimorphisms across 48 harvestman species. Using three independently derived phylogenies, we consistently found that the evolution of sexual dimorphism was correlated with that of male dimorphism, and suggest that the major force behind this relationship is the similarity between selection against intralocus sexual conflict and selection against intralocus tactical conflict. We also found that transitions in male dimorphism were more likely in the presence of sexual dimorphism, indicating that if a sexually selected trait arises on an autosome and is expressed in both sexes, its suppression in females probably evolves earlier than its suppression in small males that adopt ARTs.
Unfamiliar citations breed mistakes
Publisher: Springer Science and Business Media LLC
Date: 07-1999
DOI: 10.1038/22405
No evidence for a trade-off between sperm length and male premating weaponry
Publisher: Wiley
Date: 22-09-2015
DOI: 10.1111/JEB.12742
Abstract: Male ornaments and armaments that mediate success in mate acquisition and ejaculate traits influencing competitive fertilization success are under intense sexual selection. However, relative investment in these pre- and post-copulatory traits depends on the relative importance of either selection episode and on the energetic costs and fitness gains of investing in these traits. Theoretical and empirical work has improved our understanding of how precopulatory sexual traits and investments in sperm production covary in this context. It has recently also been suggested that male weapon size may trade off with sperm length as another post-copulatory sexual trait, but the theoretical framework for this suggestion remains unclear. We evaluated the relationship between precopulatory armaments and sperm length, previously reported in ungulates, in five taxa as well as meta-analytically. Within and between taxa, we found no evidence for a negative or positive relationship between sperm length and male traits that are important in male-male contest competition. It is important to consider pre- and post-copulatory sexual selection together to understand fitness, and to study investments in different reproductive traits jointly rather than separately. A trade-off between pre- and post-copulatory sexual traits may not manifest itself in sperm length but rather in sperm number or function. Particularly in large-bodied taxa such as ungulates, sperm number is more variable interspecifically and likely to be under more intense selection than sperm length. We discuss our and the previous results in this context.
No evidence for divergence in male harmfulness or female resistance in response to changes in the opportunity for dispersal
Publisher: Wiley
Date: 04-05-2020
DOI: 10.1111/JEB.13628
Meta‐analysis, can it ever fail?
Publisher: Wiley
Date: 03-2002
Kin-mediated plasticity in alternative reproductive tactics
Publisher: The Royal Society
Date: 04-08-2021
Abstract: Conditional strategies occur when the relative fitness pay-off from expressing a given phenotype is contingent upon environmental circumstances. This conditional strategy model underlies cases of alternative reproductive tactics, in which in iduals of one sex employ different means to obtain reproduction. How kin structure affects the expression of alternative reproductive tactics remains unexplored. We address this using the mite Rhizoglyphus echinopus , in which large males develop into aggressive ‘fighters’ and small males develop into non-aggressive ‘scramblers.’ Because only fighters kill their rivals, they should incur a greater indirect fitness cost when competing with their relatives, and thus fighter expression could be reduced in the presence of relatives. We raised mites in full-sibling or mixed-sibship groups and found that fighters were more common at higher body weights in full-sibling groups, not less common as we predicted (small in iduals were almost exclusively scramblers in both treatments). This result could be explained if relatedness and cue variability are interpreted signals of population density, since fighters are more common at low densities in this species. Alternatively, our results may indicate that males compete more intensely with relatives in this species. We provide the first evidence of kin-mediated plasticity in the expression of alternative reproductive tactics.
Heritable variation in heat shock gene expression: A potential mechanism for adaptation to thermal stress in embryos of sea turtles
Publisher: The Royal Society
Date: 13-01-2016
Abstract: The capacity of species to respond adaptively to warming temperatures will be key to their survival in the Anthropocene. The embryos of egg-laying species such as sea turtles have limited behavioural means for avoiding high nest temperatures, and responses at the physiological level may be critical to coping with predicted global temperature increases. Using the loggerhead sea turtle ( Caretta caretta ) as a model, we used quantitative PCR to characterise variation in the expression response of heat-shock genes ( hsp60, hsp70 and hsp90 molecular chaperones involved in cellular stress response) to an acute non-lethal heat shock. We show significant variation in gene expression at the clutch and population levels for some, but not all hsp genes. Using pedigree information, we estimated heritabilities of the expression response of hsp genes to heat shock and demonstrated both maternal and additive genetic effects. This is the first evidence that the heat-shock response is heritable in sea turtles and operates at the embryonic stage in any reptile. The presence of heritable variation in the expression of key thermotolerance genes is necessary for sea turtles to adapt at a molecular level to warming incubation environments.
Retraction
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-09-2011
Changes in dominance status erode personality and behavioral syndromes
Publisher: Oxford University Press (OUP)
Date: 11-10-2017
Female monopolization mediates the relationship between pre- and postcopulatory sexual traits
Publisher: Springer Science and Business Media LLC
Date: 23-01-2014
DOI: 10.1038/NCOMMS4184
Abstract: Theory predicts a trade-off between investments in precopulatory (ornaments and armaments) and postcopulatory (testes and ejaculates) sexual traits due to the costs associated with their growth and maintenance within the finite energy resources available. Empirical studies, however, have revealed considerable inconsistency in the strength and direction of relationships among these sexual traits. Ambiguity may result from variance in the marginal benefits gained by increasing investments in either pre- or postcopulatory sexual traits. Here, in a broad comparative study, we test the prediction that the relationship between pre- and postcopulatory sexual traits differs among taxa relative to the importance of male-male contest competition within them. We find that covariance between pre- and postcopulatory sexual traits gradually shifts from strongly positive to strongly negative with increasing male-male contest competition. Thus, our findings reveal a potentially unifying explanation for the oftentimes inconsistent relationships in the strength and direction of covariance among sexual traits.
Female choice and manipulations of forceps size and symmetry in the earwigForficula auriculariaL.
Publisher: Elsevier BV
Date: 08-1998
Abstract: The size and asymmetry of male secondary sexual traits are believed to convey reliable information to females concerning the quality of potential mates. Experimental manipulations of male sexual traits provide a powerful approach to the study of preference evolution. Nevertheless, the majority of studies rely on correlational evidence for selection acting on secondary sexual traits. Here we report that in three of four populations of the European earwig, Forficula auricularia, females mated sooner with males with longer forceps although there was no female preference based on forceps asymmetry. We isolated the potentially confounding influences of forceps length and asymmetry by independently manipulating each trait. Manipulations of forceps length confirmed that females preferred males with longer forceps. However, manipulations of asymmetry revealed that although females pay attention to forceps condition, they show no preferences based on asymmetry. No relationships were found between the length and asymmetry of forceps in field populations, and there were no differences in condition between symmetrical and asymmetrical males. Our results are consistent with the notion that female choice has contributed to the sexual dimorphism in earwig forceps. However, they refute the notion that fluctuating asymmetry plays a role in sexual selection. Copyright 1998 The Association for the Study of Animal Behaviour
Reduced heterozygosity depresses sperm quality in wild rabbits, Oryctolagus cuniculus
Publisher: Elsevier BV
Date: 03-2006
DOI: 10.1016/J.CUB.2006.02.059
Abstract: When close relatives are forced to reproduce, the resulting offspring inherit above average homozygosity and reduced fitness. Biologists now recognize inbreeding depression in the wild, a phenomenon that will probably increase as natural populations become depleted and fragmented. Inbreeding depression is most commonly expressed as compromised fertility and embryogenesis, but actual mechanisms remain poorly understood, especially for wild populations. Here, we examine how reduced heterozygosity influences spermatozoal and gonadal traits in wild rabbits (Oryctolagus cuniculus) s led across the United Kingdom. By using a suite of 29 microsatellite markers (analyzed to confirm representation of in idual heterozygosity across our s le), we found a significant negative relationship between heterozygosity and the production of normal sperm the relationship was significant both between (n = 12) and within (n = 91 [total males], 42 [island], 49 [mainland]) populations. Reduced heterozygosity was also associated with decreased testis size across males (n = 112), but no relationship was seen at the population level, suggesting environmental confounds. Our results show, for a wild mammal, that inbreeding is associated with decreased sperm quality, confirming suggestions of links between inbreeding and elevated sperm abnormalities in rare felids . These findings could explain why inbreeding depression so frequently arises via compromised fertility and embryogenesis .
Climate of origin affects tick (Ixodes ricinus) host-seeking behavior in response to temperature: Implications for resilience to climate change?
Publisher: Wiley
Date: 10-03-2014
DOI: 10.1002/ECE3.1014
Developmental selection against developmental instability: A direct demonstration
Publisher: The Royal Society
Date: 23-04-2013
Abstract: Developmental selection, the non-random elimination of offspring during development, is hypothesized to alter the opportunity for selection on a given trait at later stages of the life cycle. Here, we provide a direct demonstration of developmental selection against developmental instability, assessed as the incidence of minor, discrete phenotypic abnormalities in the male sex comb, a condition-dependent secondary sexual trait in Drosophila bipectinata . We exposed developing flies from two geographically separate populations to increasing levels of temperature stress, and recovered the males that died during development by teasing them out of their pupal cases. These dead males, the so-called ‘invisible fraction’ of the population, were more developmentally unstable than their surviving counterparts, and dramatically so under conditions of relatively high temperature stress. We illustrate that had these dead juvenile flies actually survived and entered the pool of sexually mature adult in iduals, their mating success would have been significantly reduced, thus intensifying sexual selection in the adult cohort for reducing developmental instability. The data suggest that without accounting for developmental selection, a study focusing exclusively on the adult cohort may unwittingly underestimate the net force of selection operating on a given phenotypic trait.
Flow Cytometric Methods for Indirect Analysis and Quantification of Gametogenesis in Chlamydomonas reinhardtii (Chlorophyceae)
Publisher: Public Library of Science (PLoS)
Date: 27-09-2016
Evaluating the genetic architecture of quantitative traits via selection followed by inbreeding
Publisher: Springer Science and Business Media LLC
Date: 09-04-2019
Patterns of threshold evolution in polyphenic insects under different developmental models
Publisher: Wiley
Date: 02-2009
DOI: 10.1111/J.1558-5646.2008.00563.X
Abstract: Two hypotheses address the evolution of polyphenic traits in insects. Under the developmental reprogramming model, in iduals exceeding a threshold follow a different developmental pathway from in iduals below the threshold. This decoupling is thought to free selection to independently hone alternative morphologies, increasing phenotypic plasticity and morphological ersity. Under the alternative model, extreme positive allometry explains the existence of alternative phenotypes and ergent phenotypes are developmentally coupled by a continuous reaction norm, such that selection on either morph acts on both. We test the hypothesis that continuous reaction norm polyphenisms, evolve through changes in the allometric parameters of even the smallest males with minimal trait expression, whereas threshold polyphenisms evolve independent of the allometric parameters of in iduals below the threshold. We compare two polyphenic species the dung beetle Onthophagus taurus, whose allometry has been modeled both as a threshold polyphenism and a continuous reaction norm and the earwig Forficula auricularia, whose allometry is best modeled with a discontinuous threshold. We find that across populations of both species, variation in forceps or horn allometry in minor males are correlated to the population's threshold. These findings suggest that regardless of developmental mode, alternative morphs do not evolve independently of one another.
Contrasting effects of landscape features on genetic structure in different geographic regions in the ornate dragon lizard, Ctenophorus ornatus
Publisher: Wiley
Date: 25-07-2013
DOI: 10.1111/MEC.12367
Abstract: Habitat fragmentation can have profound effects on the distribution of genetic variation within and between populations. Previously, we showed that in the ornate dragon lizard, Ctenophorus ornatus, lizards residing on outcrops that are separated by cleared agricultural land are significantly more isolated and hold less genetic variation than lizards residing on neighbouring outcrops connected by undisturbed native vegetation. Here, we extend the fine-scale study to examine the pattern of genetic variation and population structure across the species' range. Using a landscape genetics approach, we test whether land clearing for agricultural purposes has affected the population structure of the ornate dragon lizard. We found significant genetic differentiation between outcrop populations (FST = 0.12), as well as isolation by distance within each geographic region. In support of our previous study, land clearing was associated with higher genetic ergences between outcrops and lower genetic variation within outcrops, but only in the region that had been exposed to intense agriculture for the longest period of time. No other landscape features influenced population structure in any geographic region. These results show that the effects of landscape features can vary across species' ranges and suggest there may be a temporal lag in response to contemporary changes in land use. These findings therefore highlight the need for caution when assessing the impact of contemporary land use practices on genetic variation and population structure.
Paternal effects on the expression of a male polyphenism
Publisher: Wiley
Date: 04-05-2012
DOI: 10.1111/J.1558-5646.2012.01662.X
Abstract: Polyphenic traits are widespread, but compared to other traits, relatively few studies have explored the mechanisms that influence their inheritance. Here we investigated the relative importance of additive, nonadditive genetic, and parental sources of variation in the expression of polyphenic male dimorphism in the mite Rhizoglyphus echinopus, a species in which males are either fighters or scramblers. We established eight inbred lines through eight generations of full-sibling matings, and then crossed the inbred lines in a partial diallel design. Nymphs were isolated and raised to adulthood with ad libitum food. At adulthood, male morph was recorded for all male offspring. Using a Cockerham-Weir model, we found strong paternal effects for this polyphenic trait that could be either linked to the Y chromosome of males or an indirect genetic effect that is environmentally transmitted. In additional analyses, we were able to corroborate the paternal effects but also detected significant additive effects questioning the Cockerham-Weir analysis. This study reveals the potential importance of paternal effects on the expression of polyphenic traits and sheds light on the complex genetic architecture of these traits.
On female choice, heterozygosity and the lek paradox
Publisher: Elsevier BV
Date: 2008
Social cues affect quantitative genetic variation and covariation in animal personality traits
Publisher: Wiley
Date: 24-01-2019
DOI: 10.1111/EVO.13661
Abstract: The social environment is expected to have substantial effects on behavior, and as a consequence, its heritability and evolvability. We investigated these effects by exposing Australian field crickets (Teleogryllus oceanicus) to either silence or recordings of male acoustic sexual signals. We used a combined pedigree and full-sib/half-sib breeding design to estimate the repeatability, heritability, and evolvability of behaviors related to boldness, exploration, and activity. All behaviors measured were significantly repeatable in both social environments. Additionally, most behaviors showed significant heritabilities in the two environments. We found no difference in repeatabilities between the silent and the acoustic environment but did find significant differences in the heritabilities and evolvabilities between these environments. There was a high degree of similarity between the phenotypic covariance matrices across the two environments, while the genotypic covariance matrices were highly dissimilar. Reflecting this, we found significant genotype-by-environment interactions for most of the behaviors. Lastly, we found that the repeatable aspect of behavior ("personality") was significantly heritable for most behaviors, but that these heritabilities were higher in the acoustic than in the silent environment. We conclude that the social environment can have a significant impact on the heritability and evolvability of behavior, and argue that evolutionary inferences from phenotypic studies should be made with caution.
Related Organisations
Related Funding Activities
Discovery Projects - Grant ID: DP210100868
Start Date: 07-2021
End Date: 12-2024
Amount: $378,087.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0663746
Start Date: 07-2006
End Date: 12-2009
Amount: $185,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP170100554
Start Date: 2017
End Date: 12-2020
Amount: $400,000.00
Funder: Australian Research Council
View Funded ActivityARC Future Fellowships - Grant ID: FT110100500
Start Date: 2012
End Date: 12-2017
Amount: $818,156.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0557849
Start Date: 07-2005
End Date: 04-2011
Amount: $670,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP130100783
Start Date: 2013
End Date: 12-2017
Amount: $324,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP220100120
Start Date: 2022
End Date: 12-2025
Amount: $563,312.00
Funder: Australian Research Council
View Funded Activity