Ecological and Evolutionary Response of Natural Populations to Climate Change: The Role of Phenotypic Plasticity
Final Report Abstract
Climate change affects the phenology of life cycle events in a variety of taxa, and many bird species of temperate regions have responded to increasing spring temperatures by shifting their timing of reproduction towards earlier breeding over the last decades. However, the relative contributions of phenotypic plasticity and microevolutionary responses to the widely observed trends on the population level remain unclear. Disentangling these fundamental biological mechanisms and quantifying their relative contribution is of crucial importance for predicting how populations will respond to future climate change and for informing managing decisions. In this project, I analysed a data set of more than 3100 breeding events from a pedigreed German pied flycatcher Ficedula hypoleuca population. Tracking increasing spring temperatures, this population has shifted forward the timing of reproduction more than 14 days over the last 37 years. Analysis of multiple observations of the same individuals under different spring temperatures demonstrated that individual phenotypic plasticity in the timing of reproduction is powerful enough to explain entirely the massive forward shift on the population level. Moreover, although variation in the timing of reproduction had a heritable component and could therefore evolve in response to climate change related selection for earlier breeding, quantitative genetic analysis revealed no evidence for any microevolutionary shifts in the genetic composition of the study population. In conclusion, the main results from this study suggest that the evolved, contemporary levels of phenotypic plasticity in the timing of reproduction were sufficient to enable this particular population to track the increase in spring temperatures without a need for evolutionary rescue by adaptive microevolutionary changes. However, it is an open and important question for future research to what degree these results can be generalised to other populations of the pied flycatcher across its extended European breeding grounds or to other species that are just as well subject to climate change.
