ORCID Profile
0000-0002-9843-926X
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Publisher: Cold Spring Harbor Laboratory
Date: 05-06-2017
DOI: 10.1101/146076
Abstract: Recent theory suggests that male coercion could contribute to the maintenance of obligate sex. However, it is unclear how sexually antagonistic coevolution might interact with mate scarcity to influence the probability of invasions of obligately sexual populations by mutants capable of parthenogenetic reproduction. Furthermore, if invasion does occur, it is unclear which factors promote or prevent the complete loss of sex. Using in idual-based models, we show that male coercion cannot prevent the invasion of a mutant allele that gives virgin females the ability to reproduce parthenogenetically because mutants always benefit by producing at least some offspring asexually prior to mating. Indeed, the likelihood of invasion generally increases as sexual conflict intensifies, and the effects of sexual conflict and mate scarcity can interact in complex ways to promote invasion. Nonetheless, we find that coercion prevents the complete loss of sex unless linkage disequilibrium can build up between the mutant allele and alleles for effective female resistance. Our findings clarify how costs and limitations of female resistance can promote the maintenance of sexual reproduction, turning sex into an evolutionary trap. At the same time, our results highlight the need to explain why facultative reproductive strategies so rarely evolve in nature.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.TREE.2017.06.002
Abstract: Theory suggests that occasional or conditional sex involving facultative switching between sexual and asexual reproduction is the optimal reproductive strategy. Therefore, the true 'paradox of sex' is the prevalence of obligate sex. This points to the existence of powerful, general impediments to the invasion of obligately sexual populations by facultative mutants, and recent studies raise the intriguing possibility that a key impediment could be sexual conflict. Using Bateman gradients we show that facultative asexuality can lify sexual conflict over mating, generating strong selection for both female resistance and male coercion. We hypothesize that invasions are most likely to succeed when mutants have negative Bateman gradients, can avoid mating, and achieve high fecundity through asexual reproduction - a combination unlikely to occur in natural populations.
Publisher: Cold Spring Harbor Laboratory
Date: 20-11-2019
DOI: 10.1101/846287
Abstract: Transgenerational plasticity (TGP) occurs when the environment experienced by parents induces changes in traits of offspring and/or subsequent generations. Such effects can be adaptive or non-adaptive and are increasingly recognised as key determinants of health, cognition, development and performance across a wide range of taxa, including humans. While the conditions that favour maternal TGP are well understood, rapidly accumulating evidence indicates that TGP can be maternal or paternal, and offspring responses can be sex-specific. However, the evolutionary mechanisms that drive this ersity are unknown. We used an in idual-based model to investigate the evolution of TGP when the sexes experience different ecologies. We find that adaptive TGP rarely evolves when alleles at loci that determine offspring responses to environmental information originating from the mother and father are subject to sexually antagonistic selection. By contrast, duplication and sex-limitation of such loci can allow for the evolution of a variety of sex-specific responses, including non-adaptive sex-specific TGP when sexual selection is strong. Sexual conflict could therefore help to explain why adaptive TGP evolves in some species but not others, why sons and daughters respond to parental signals in different ways, and why complex patterns of sex-specific TGP may often be non-adaptive.
Publisher: California Digital Library (CDL)
Date: 23-03-2021
Publisher: Wiley
Date: 08-06-2022
Abstract: In facultatively parthenogenetic populations, the prevalence of sexual reproduction depends on whether females mate and therefore produce sons and daughters or avoid mating and produce daughters only. The relative advantage of mating in such species may depend on a female's own reproductive origin (i.e. development from a fertilised or unfertilised egg) if parthenogenesis reduces heterozygosity similar to sexual inbreeding, or if it inhibits mating, sperm storage or fertilisation. But effects of reproductive origin on development and performance are poorly understood. Using the facultatively parthenogenetic stick insect, Extatosoma tiaratum , we quantified morphology, mating probability, and reproductive success in mated versus unmated females of sexual versus automictic (parthenogenetic) origin. We found strong evidence that increased homozygosity negatively impacted some traits in parthenogenetically produced females: compared to sexually produced females, parthenogenetically produced females were smaller and more prone to deformities in vestigial wings, but not more prone to fluctuating asymmetry in their legs. Parthenogenetically produced females received fewer mating attempts and avoided mating more often than sexually produced females. Yet, contrary to the expectation that sex should rescue parthenogenetic lineages from the detrimental effects of increased homozygosity, parthenogenetically produced females gained no net reproductive benefit from mating, suggesting that physiological constraints limit fitness returns of sexual reproduction for these females. Our findings indicate that advantages of mating in this species depend on female reproductive origin. These results could help to explain spatial distributions of sex in facultatively parthenogenetic animals and evolutionary transitions to obligate asexuality. Read the free Plain Language Summary for this article on the Journal blog.
Publisher: The Royal Society
Date: 27-08-2018
Abstract: Obligately asexual organisms tend to occur at higher altitudes or latitudes and occupy larger ranges than their obligately sexual relatives—a phenomenon called geographical parthenogenesis. Some facultatively parthenogenetic organisms that reproduce both sexually and asexually also exhibit spatial variation in reproductive mode. Theory suggests that sexual conflict and mate limitation can determine the relative frequency of sex in facultative parthenogens, but the effect of these dynamics on spatial distributions is unknown. Here, we use in idual-based models to investigate whether these dynamics can generate local differences in the reproductive mode in a facultatively parthenogenetic metapopulation occupying an environmental gradient. We find that selection for resistance and high fecundity creates positive epistasis in virgin females between a mutant allele for parthenogenesis and alleles for resistance, resulting in female-biased sex ratios and higher resistance and coercion towards the productive ‘core’ of the metapopulation. However, steeper environmental gradients, which lead to lower density and less mating at the ‘edge’, generate female bias without promoting coercion or resistance. Our analysis shows that local adaptation of facultatively parthenogenetic populations subject to sexual conflict and productivity gradients can generate striking spatial variation suggesting new patterns for empirical investigation. These findings could also help to explain the rarity of facultative parthenogenesis in animals. This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences'.
Publisher: Wiley
Date: 06-02-2018
DOI: 10.1002/ECE3.3895
Publisher: Cold Spring Harbor Laboratory
Date: 03-11-2022
DOI: 10.1101/2022.11.02.514965
Abstract: Transitions from sexual to asexual reproduction have occurred in numerous lineages across the tree of life, but it remains unclear why asexual populations rarely persist. In facultatively parthenogenetic animals, all-female populations can arise when males are absent or become extinct, and such populations can give rise to obligately asexual species. Facultative parthenogens could therefore shed light on the initial stages of transitions to asexuality, and the factors that determine the success or failure of asexual populations. Here, we describe a novel spatial mosaic of mixed-sex and all-female populations of the facultatively parthenogenetic Australian phasmid Megacrania batesii , and use this system to investigate the consequences of reproductive mode variation in the wild. Analysis of single nucleotide polymorphisms (SNPs) indicated multiple, independent transitions between reproductive modes. As expected, all-female populations had drastically reduced heterozygosity and genetic ersity relative to mixed-sex populations. However, we found few consistent differences in fitness-related traits between population types. All-female populations exhibited more frequent and severe (non-functional) wing deformities, but did not show higher rates of appendage loss. All-female populations also harbored more parasites, but only in certain habitats. Reproductive mode explained little variation in female body size, fecundity, or egg hatch-rate. Our results confirm that transitions to parthenogenetic reproduction can lead to dramatic reductions in genetic ersity and heterozygosity. However, our findings also suggest that asexual M. batesii populations consist of high-fitness genotypes that might be able to thrive for many generations, perhaps until they encounter a drastic environmental change to which they are unable to adapt.
No related grants have been discovered for Nathan W Burke.