Natural selection: methodological constraints and climatic drivers

Dr Pascal Marrot

CNRS Toulouse, France

Date: Wednesday, 13.02.2019, 13:00, Cent Lecture Theatre 0142                                         How to get there: Lecture theatre 0142 is c. ~15 meters to the right after entering CeNT

Abstract. Global change results in an increase in temperature mean and variability and generates new environmental conditions for wild populations. In order to respond to this new threat, wild populations can move to another place (dispersion), change their behaviour or their phenology (phenotypic plasticity), or respond by evolutionary change (involving changes in alleles frequency). While many examples of phenotypic plasticity and dispersion have been observed in the wild, empirical detection of evolutionary responses to climate change remains rare. During my PhD, I studied natural selection induced by climate change (both in term of warming and extreme event frequency) acting on monitored population of blue tits (Cyanistes caeruleus) in southern France monitored for the past 26 years. Supporting past results for the Mediterranean region (known as a “hot spot” of climate warming), our climatic analyses revealed a strong warming in our study site, especially in spring (+ 0.6°C / decades since 1970). This warming was correlated with an increase in natural selection strength for earlier breeding. In fact, our results indicated an increase in the strength of selection by 46% every +1°C anomalies in maximum April temperature. Beyond this selective impact of the warming trend, we detected an impact of extreme hot days occurrence, independently of mean temperature trend: when 10% of broods in the population experienced this type of extreme climatic event, selection for earlier breeding increased by 39%. This study confirmed the selective impact of warming, pointing out a potential evolutionary response to climate change in the future.

Photo credit: Stephane Tillo