Heat-induced maternal effects shapes avian eggshell traits and embryo response to high temperatures

Populations without a sufficient rate of genetic adaptation may risk extinction in the face of rapid environmental change, however, phenotypic plasticity can facilitate their persistence. For example, mothers can prepare offspring for the thermal environment young will experience through transgenerational plasticity. In oviparous species, whether mothers can prepare offspring to cope with thermal stress experienced as embryos is largely unknown. We demonstrate that when zebra finch mothers are exposed to a heat stress, their offspring show altered heart rates as embryos in response to high incubation temperatures, as well as an increase in eggshell pore density that was positively correlated with survival. These results are the first to show that temperature induced transgenerational plasticity may promote embryonic survival in an oviparous species.