Female mating preferences for outbred versus inbred males are conditional upon the female's own inbreeding status

Inbreeding occurs when relatives mate with each other, and it often has detrimental effects for the fitness of any resulting offspring. It is an important issue in ecology and evolutionary biology with profound implications for genetic variation and the evolution of mating systems and reproductive strategies. For example, inbreeding may shape mate choice through the avoidance of outbred, related individuals to prevent inbreeding, or through the avoidance of inbred, unrelated individuals that have been produced through inbreeding. Although the former has been studied extensively, little is known about mating preferences based on the inbreeding status of potential partners. It is also unclear whether these mating preferences are influenced by the inbreeding status of the choosing sex. Here, we examined female mating preferences for outbred versus inbred males using dichotomous choice tests in the burying beetle Nicrophorus vespilloides. We found that these mating preferences were conditional upon the female's own inbreeding status: inbred females preferentially mated with outbred males, whereas outbred females did not show such a preference. Our findings suggest that inbred males suffer reduced mating success only when interacting with inbred females. In species where this is the case, the fitness costs of inbreeding with respect to male mating success will therefore depend on the frequency of inbred females relative to outbred females, which depends on the rate of inbreeding in the population

Ecology of Botfly Parasitism in White-Footed Mice (Peromyscus leucopus)

White-footed mice (Peromyscus leucopus) are an abundant species in eastern deciduous forests. The objective of this study was to examine the ecology of botfly parasitism in a white footed mouse population in the Brockport Woods, Brockport, NY. I analyzed data collected by live trapping in May and September from 1993 to 2009. Males and females exhibited similar levels of botfly infestation. When a greater percentage of mice was infected with botflies, there was a significant increase in average body mass. I also found that as fall trap success increased, the proportion of mice with botflies decreased, but the number of infected mice remained relatively constant over time. This may be due to the fluctuation of P. leucopus populations, which is characterized by rapid increases and sudden collapses, so there may not be enough botflies to take advantage of all the available hosts at high densities. Botfly infection did not have an impact on overwinter survival. Lastly, spring abundance was most affected by trap success in the previous fall and two weather variables; spring abundance increased when fall trap success and mean January temperature increased and when total January snowfall decreased. These three variables, however, did not explain all of the observed variability in abundance. Population fluctuations in P. leucopus are complex, so future studies should look at other factors that could be responsible for driving abundance of this species

Predation risk reduces a female preference for heterospecific males in the green swordtail

The presence of a predator can result in the alteration, loss or reversal of a mating preference. Under predation risk, females often change their initial preference for conspicuous males, favouring less flashy males to reduce the risk of being detected by predators. Previous studies on predator-induced plasticity in mate preferences have given females a choice between more and less conspicuous conspecific males. However, in species that naturally hybridize, it is also possible that females might choose an inconspicuous heterospecific male over a conspicuous conspecific male under predation risk. Our study addresses this question using the green swordtail (Xiphophorus helleri) and the southern platyfish (Xiphophorus maculatus), which are sympatric in the wild. We hypothesized that X. helleri females would prefer the sworded conspecific males in the absence of a predator but favour the less conspicuous, swordless, heterospecific males in the presence of a predator. Contrary to our expectation, females associated more with the heterospecific male than the conspecific male in the control (no predator) treatment, and they were non-choosy in the predator treatment. This might reflect that females were attracted to the novel male phenotype when there was no risk of predation but became more neophobic after predator exposure. Regardless of the underlying mechanism, our results suggest that predation pressure may affect female preferences for conspecific versus heterospecific males. We also found striking within-population, between-individual variation in behavioural plasticity: females differed in the strength and direction of their preferences, as well as in the extent to which they altered their preferences in response to changes in perceived predation risk. Such variation in female preferences for heterospecific males could potentially lead to temporal and spatial variation in hybridization rates in the wild

Sexual selection and environmental change : what do we know and what comes next?

Funding: M.A. was supported by the Swiss National Science Foundation (Early Postdoc Mobility Fellowship No. P2SKP3_184052) during part of the time devoted to this work.Publisher PDFPeer reviewe

Effects of prior contest experience and contest outcome on female reproductive decisions and offspring fitness

Winning or losing a prior contest can influence the outcome of future contests, but it might also alter subsequent reproductive decisions. For example, losers may increase their investment in the current breeding attempt if losing a contest indicates limited prospects for future breeding. Using the burying beetle Nicrophorus vespilloides, we tested whether females adjust their prehatching and posthatching reproductive effort after winning or losing a contest with a same-sex conspecific. Burying beetles breed on carcasses of small vertebrates for which there is fierce intrasexual competition. We found no evidence that winning or losing a contest influenced reproductive investment decisions in this species. Instead, we show that a female’s prior contest experience (regardless of its outcome) influenced the amount of posthatching care provided, with downstream consequences for the female’s reproductive output; both winners and losers spent more time provisioning food to their offspring and produced larger broods than females with no contest experience. We discuss the wider implications of our findings and present a conceptual model linking contest-mediated adjustments in parental investment to population-level processes. We propose that the frequency of intraspecific contests could both influence and be influenced by population dynamics in species where contest experience influences the size and/or number of offspring produced

The consequences of heatwaves for animal reproduction are timing-dependent

The study was funded by a SULSA Early Career Researcher Prize and a Royal Society Research Grant awarded to NP (RGS\R1\211295).In light of the increased frequency of heatwaves due to climate change, it is crucial to better understand their potential effects on animal reproduction. Heat stress can affect all aspects of reproduction, including gamete development, fertilisation success, parental care and offspring survival. We may, therefore, expect these effects to be highly sensitive to the timing of a heatwave event relative to an organism's reproductive cycle. Here, we use an insect study system (Nicrophorus vespilloides) to test whether variation in the timing of a heatwave within a short timeframe has differential effects on reproductive success and offspring fitness. We found that heatwaves had little to no effect when they occurred a few days before or after mating, but they were highly detrimental for fitness if they occurred during mating. Individuals that experienced a heatwave during mating were significantly less likely to have a successful breeding bout, had a longer breeding bout, and their offspring were smaller and suffered a lower survival rate. Our study shows that variation in the timing of a heatwave event over very short timescales (on the order of days) can have drastically different consequences for animal reproduction. This work provides novel insights into the vulnerability of organisms at different stages of their reproductive cycle and can improve our ability to make informed predictions about the ecological consequences of heatwaves under climate change.Publisher PDFPeer reviewe

Does phenotypic plasticity initiate developmental bias?

Acknowledgements We thank attendees and organizers of the “developing a theory of developmental bias” workshop for stimulating discussion on the topics in this manuscript. We are grateful to Matt Wund and an anonymous reviewer who provided thoughtful and constructive comments that helped to improve the manuscript. We also thank Calum Campbell,Joey Humble, and Iain Hill for photographing sticklebacks that were used to generate Figure 2. This paper was partially supported by NERC grant NE/N016734/1 and by an EPSRC studentship grant EP/M508056/1.Peer reviewedPublisher PD

Multigenerational exposure to elevated temperatures leads to a reduction in standard metabolic rate in the wild

In light of global climate change, there is a pressing need to understand and predict the capacity of populations to respond to rising temperatures. Metabolic rate is a key trait that is likely to influence the ability to cope with climate change. Yet, empirical and theoretical work on metabolic rate responses to temperature changes has so far produced mixed results and conflicting predictions. Our study addresses this issue using a novel approach of comparing fish populations in geothermally warmed lakes and adjacent ambient‐temperature lakes in Iceland. This unique ‘natural experiment' provides repeated and independent examples of populations experiencing contrasting thermal environments for many generations over a small geographic scale, thereby avoiding the confounding factors associated with latitudinal or elevational comparisons. Using Icelandic sticklebacks from three warm and three cold habitats, we measured individual metabolic rates across a range of acclimation temperatures to obtain reaction norms for each population. We found a general pattern for a lower standard metabolic rate in sticklebacks from warm habitats when measured at a common temperature, as predicted by Krogh's rule. Metabolic rate differences between warm‐ and cold‐habitat sticklebacks were more pronounced at more extreme acclimation temperatures, suggesting the release of cryptic genetic variation upon exposure to novel conditions, which can reveal hidden evolutionary potential. We also found a stronger divergence in metabolic rate between thermal habitats in allopatry than sympatry, indicating that gene flow may constrain physiological adaptation when dispersal between warm and cold habitats is possible. In sum, our study suggests that fish may diverge toward a lower standard metabolic rate in a warming world, but this might depend on connectivity and gene flow between different thermal habitats

Evolvability under climate change: bone development and shape plasticity are heritable and correspond with performance in Arctic charr (Salvelinus alpinus)

Environmental conditions can impact the development of phenotypes and in turn the performance of individuals. Climate change, therefore, provides a pressing need to extend our understanding of how temperature will influence phenotypic variation. To address this, we assessed the impact of increased temperatures on ecologically significant phenotypic traits in Arctic charr (Salvelinus alpinus). We raised Arctic charr at 5°C and 9°C to simulate a predicted climate change scenario and examined temperature-induced variation in ossification, bone metabolism, skeletal morphology, and escape response. Fish reared at 9°C exhibited less cartilage and bone development at the same developmental stage, but also higher bone metabolism in localized regions. The higher temperature treatment also resulted in significant differences in craniofacial morphology, changes in the degree of variation, and fewer vertebrae. Both temperature regime and vertebral number affected escape response performance, with higher temperature leading to decreased latency. These findings demonstrate that climate change has the potential to impact development through multiple routes with the potential for plasticity and the release of cryptic genetic variation to have strong impacts on function through ecological performance and survival

Geothermal stickleback populations prefer cool water despite multigenerational exposure to a warm environment

Given the threat of climate change to biodiversity, a growing number of studies are investigating the potential for organisms to adapt to rising temperatures. Earlier work has predicted that physiological adaptation to climate change will be accompanied by a shift in temperature preferences, but empirical evidence for this is lacking. Here, we test whether exposure to different thermal environments has led to changes in preferred temperatures in the wild. Our study takes advantage of a “natural experiment” in Iceland, where freshwater populations of threespine sticklebacks (Gasterosteus aculeatus) are found in waters warmed by geothermal activity year-round (warm habitats), adjacent to populations in ambient-temperature lakes (cold habitats). We used a shuttle-box approach to measure temperature preferences of wild-caught sticklebacks from three warm–cold population pairs. Our prediction was that fish from warm habitats would prefer higher water temperatures than those from cold habitats. We found no support for this, as fish from both warm and cold habitats had an average preferred temperature of 13°C. Thus, our results challenge the assumption that there will be a shift in ectotherm temperature preferences in response to climate change. In addition, since warm-habitat fish can persist at relatively high temperatures despite a lower-temperature preference, we suggest that preferred temperature alone may be a poor indicator of a population's adaptive potential to a novel thermal environment