Mating system affects population performance and extinction risk under environmental challenge

Failure of organisms to adapt to sudden environmental changes may lead to extinction. The type of mating system, by affecting fertility and the strength of sexual selection, may have a major impact on a population's chances to adapt and survive. Here, we use experimental evolution in bulb mites (Rhizoglyphus robini) to examine the effects of the mating system on population performance under environmental change. We demonstrate that populations in which monogamy was enforced suffered a dramatic fitness decline when evolving at an increased temperature, whereas the negative effects of change in a thermal environment were alleviated in polygamous populations. Strikingly, within 17 generations, all monogamous populations experiencing higher temperature went extinct, whereas all polygamous populations survived. Our results show that the mating system may have dramatic effects on the risk of extinction under environmental change

Relative costs and benefits of alternative reproductive phenotypes at different temperatures : genotype-by-environment interactions in a sexually selected trait

Abstract Background The maintenance of considerable genetic variation in sexually selected traits (SSTs) is puzzling given directional selection expected to act on these traits. A possible explanation is the existence of a genotype-by-environment (GxE) interaction for fitness, by which elaborate SSTs are favored in some environments but selected against in others. In the current study, we look for such interactions for fitness-related traits in the bulb mite, a male-dimorphic species with discontinuous expression of a heritable SST in the form of enlarged legs that are used as weapons. Results We show that evolution at 18 °C resulted in populations with a higher prevalence of this SST compared to evolution at 24 °C. We further demonstrate that temperature modified male reproductive success in a way that was consistent with these changes. There was a genotype-by-environment interaction for reproductive success – at 18 °C the relative reproductive success of armored males competing with unarmored ones was higher than at the moderate temperature of 24 °C. However, male morph did not have interactive effects with temperature with respect to other life history traits (development time and longevity). Conclusions A male genotype that is associated with the expression of a SST interacted with temperature in determining male reproductive success. This interaction caused an elaborate SST to evolve in different directions (more or less prevalent) depending on the thermal environment. The implication of this finding is that seasonal temperature fluctuations have the potential to maintain male polymorphism within populations. Furthermore, spatial heterogeneity in thermal conditions may cause differences among populations in SST selection. This could potentially cause selection against male immigrants from populations in different environments and thus strengthen barriers to gene flow

No evidence for reproductive isolation through sexual conflict in the bulb mite Rhizoglyphus robini

Sexual conflict leading to sexual antagonistic coevolution has been hypothesized to drive reproductive isolation in allopatric populations and hence lead to speciation. However, the generality of this speciation mechanism is under debate. We used experimental evolution in the bulb mite Rhizoglyphus robini to investigate whether sexual conflict promotes reproductive isolation measured comprehensively to include all possible pre- and post-zygotic mechanisms. We established replicate populations in which we either enforced monogamy, and hence removed sexual conflict by making male and female evolutionary interests congruent, or allowed promiscuity. After 35 and 45 generations of experimental evolution, we found no evidence of reproductive isolation between the populations in any of the mating systems. Our results indicate that sexual conflict does not necessarily drive fast reproductive isolation and it may not be a ubiquitous mechanism leading to speciation

Sexual conflict in a changing environment

Sexual conflict has extremely important consequences for various evolutionary processes including its effect on local adaptation and extinction probability during environmental change. The awareness that the intensity and dynamics of sexual conflict is highly dependent on the ecological setting of a population has grown in recent years, but much work is yet to be done. Here, we review progress in our understanding of the ecology of sexual conflict and how the environmental sensitivity of such conflict feeds back into population adaptivity and demography, which, in turn, determine a population's chances of surviving a sudden environmental change. We link two possible forms of sexual conflict – intralocus and interlocus sexual conflict – in an environmental context and identify major gaps in our knowledge. These include sexual conflict responses to fluctuating and oscillating environmental changes and its influence on the interplay between interlocus and intralocus sexual conflict, among others. We also highlight the need to move our investigations into more natural settings and to investigate sexual conflict dynamics in wild populations

full_dataset

The number of eggs (fecundity) and fertility (fertile collumn; fertile females are coded with 1 and infertile with 0) of females from scrambler (s) and fighter (f) selected lines (sel) at different temperatures (temp). Line identities are given in lineID collumn