The role of contemporary evolution in shaping life history, demography and the fate of functional genetic variation in natural populations

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Evolutionary biology has undergone a small revolution with the recent demonstration that evolution by natural selection can be detected over just a few years or decades in the wild. For example, there is evidence that selection due to global warming can modify the timing of reproductive timing in animals at the genetic level. This raises major questions about the importance and consequences of rapid evolution in contemporary natural populations, e.g. how evolution contributes to their short-term adaptation and alters ecological processes such as population dynamics. My research programme will address these questions by following genetic variation "in real time", namely generation-by-generation, using genealogical and molecular data. I will use the French-Canadian population from Québec as a model to study life-history traits (e.g., fertility, lifespan) evolution. Exceptional data spanning four centuries, and unequalled by long-term animal data sets, is available for this population. Previously, I documented a microevolutionary change (i.e. a genetic response to natural selection) in the age at first reproduction of women in a regional population from Québec over 140 years. With my Discovery Grant, I will assess the heterogeneity of such evolutionary responses across populations facing similar or different environmental conditions. I will then quantify how temporal changes in life history moulded the demography of populations. Rapid life history evolution can also have cascading effects on functionally important genetic variants. Hence, I will develop a new class of models that will allow the measurement, across generations, of natural selection on variants affecting organismal condition and lifespan, to link dynamically changes in life history to those in the frequency of genetic variants. By following molecular variation across generations, I will also test the "mother's curse", an important hypothesis that could partly explain the faster senescence and shorter lifespan of males in many species. This programme will thus follow a logical sequence by investigating the feedback loop "life-history trait evolution->demography->variant frequencies-> life-history trait evolution". It should provide major insights into how contemporary evolution shapes the dynamics of population and their adaptation. This issue is most relevant within the context of global environmental changes that modern living organisms are currently facing.