Evolvability of phenotypic plasticity under environmental variation in a population of pied flycatchers, Ficedula hypoleuca
One of the major goals in evolutionary biology is to understand how the interplay between natural selection and genetic variation results in local adaptation. However, quantification of evolutionary adaptation of populations in temporally changing environments is not widely spread, particularly in life-history traits like laying date in birds. On the one side, microevolutionary responses to climate change for advanced laying date are lacking despite consistent selection for early phenology. Alternatively, local adaptation may occur without genetic change when? evolution favours phenotypic plasticity. Here, we explored the relative role of microevolution and phenotypic plasticity as evolutionary mechanisms in relation to 17 climatic factors. In a long-term study in Spain (1987-2016) of an individually-based monitored population of pied flycatchers (Ficedula hypoleuca), we took advantage of “animal models” to explore the genetic basis of phenotypic plasticity and microevolution of laying date. Our results show 1), no net temporal change in mean laying date but high yearly variation in all climatic variables considered; 2) a dramatic increase in population density; 3) a small heritability and a lack of temporal trend in the genetic part of laying date (breeding value) 4) statistical support for genotype-by-environment interaction (plasticity), considering the two climatic factors that best explain selection on laying date in our population: variation in spring temperature and mean North Atlantic Oscillation in winter. Considering the presence of a genotype-by-environment interaction and the increase in population density, our results support the idea that evolution may favor local adaptation by favouring more plastic genotypes able to adapt to stochastic environments.