Context dependence of transgenerational plasticity: the influence of parental temperature depends on offspring environment and sex.

Under environmental change, the relationship between phenotype and fitness can change rapidly, leaving populations vulnerable. Plasticity within and between generations could provide the fastest mitigation to environmental change. However, plasticity may depend on interactions among parental environment, offspring environment and offspring sex, and we know little of how these interactions manifest. We examine the importance of parental and offspring thermal environment in the context of a terrestrial ectotherm (the jacky lizard, Amphibolurus muricatus), where the thermal environment depends on complex thermoregulatory behaviours. By manipulating both parental and offspring thermoregulatory (basking) opportunities in a full factorial design, we found that transgenerational plasticity was highly context dependent. Overall, longer parental thermoregulatory opportunities led to increased growth in offspring, providing a clear fitness benefit to daughters but inducing a cost of increased oxidative stress in sons. Daughters, but not sons, received the greatest advantage when their thermal environment matched that of their parents. The offspring thermal environment had little independent effect on offspring phenotype. Together, the results suggest that both directional selection on offspring size (leading to growth being dependent on thermal conditions) and selection for anticipatory parental effects operate, but with a different balance in males and females. More broadly, restrictions in thermoregulatory opportunities under climatic warming will have negative consequences both within and between generations, but the exact nature will depend on the evolved functional form of plasticity.

Female mice seek refuge from castrated males, but not intact or vasectomized males, mitigating a socially-induced glucocorticoid response.

Sexual conflict may be manifested during social interactions, shaping the costs of reproduction in sexually reproducing species. This conflict, and the physical necessity of intromission, can intensify the already costly nature of reproduction for female mammals. To identify and partition the costs that males inflict on females during mating and reproduction, we paired female mice with either other females or castrated, vasectomised, or intact (sham-vasectomised) males, thus manipulating exposure to social mating behavior and costs arising from fertilization. We also provided females with refuges where males could not enter, to test whether females show avoidance or attraction to males of different gonadal status expected to exhibit different levels of social behavior. We found that females paired with vasectomised and castrated males spent the most time in their refuge. Females housed with castrated males also had increased glucocorticoid levels, an effect that was mitigated when females could retreat from these males to a refuge. This suggests that females actively refuge from castrated males, and that housing with such males is sufficient to generate an increased glucocorticoid response. Our results show that females choose to refuge from males depending on the partner's gonadal status, choices that are linked to social induced stress responses but not exposure to male mating behaviour.