ERC Starting Grant SHE: Multi-level Selection in a Heterogeneous Environment Grant agreement no. 337365
Context of the project:
While many theoretical models predict how traits should evolve under natural and sexual selection, measures of traits in wild plants or animals shows that these rarely follow the predictions we can make. One of the reasons for our limited ability to predict evolution in the wild is that we lack temporal and spatial replication in our observations, we lack studies on traits other than morphology, and we lack of statistical power.
Our ERC project ‘SHE’ (Selection in a Heterogeneous Environment) offers to integrate measures of selection at multiple levels (selection acting on phenotypic, additive genetic and genomic variations) for multiple potentially correlated traits (morphology, life-history, sexual ornament and personality) and across space and time.
We will use data from a long-term monitoring project of blue titsCyanistes caeruleus and great titsParus major in multiple Mediterranean study sites at the southern edge of the species range. First, a phenotypic approach will measure present selection on combinations of traits, and explore spatio-temporal fluctuations of selection. We will especially test the importance of selection during extreme climatic events, of particular relevance in a region identified as a main climate change ‘hotspot’, as well as selection in an urban context. Second, a quantitative genetic approach will estimate how fluctuating selection can impact evolutionary potential, and will predict the future evolutionary response to selection, independently of possible confounding environmental covariances between fitness and the focal traits. Third, an ecological genomics approach will analyze the genomic regions found to be associated with phenotypic variation in terms of genetic structure, genetic diversity patterns and footprints of selection, thereby providing insights into past selection that has shaped phenotypic variation. We will explore the habitat-specific genetic architecture of two fundamental traits expected to be under divergent selection in evergreen/ deciduous forests and in urban/rural habitats: timing of breeding and personality.
Where are we at now?
So far, we have used data from a long-term monitoring project of blue tits in multiple Mediterranean study sites at the southern edge of the species range, to show that the selection force and direction can vary greatly across different habitats, and also over time. The temporal fluctuations of selection can in part be attributed to climatic factors, with for example the recent warming resulting in a much stronger selection favouring earlier reproduction. We have also analysed specifically the ecological and evolutionary consequences of extreme climatic events, of particular relevance in a region identified as a main climate change ‘hotspot’.
Second, a comparison between urban and rural great tits has revealed two distinct urban and rural ecotypes with differences between the urban and rural ecotypes in their morphology, their life history, but also their personality, or behavioural syndromes. We are presently measuring and comparing evolution in action in the urban and forest habitats.
Third, an ecological genomics approach has revealed a habitat-specific genetic architecture in blue tits breeding in Corsica, adding further support to the hypothesis of local adaptation in the evergreen and deciduous patches. Reversely no genetic structure was found in the urban great tits, suggesting important gene flow between the areas more or less urbanized. Further genomic analyses will in the future allow to analyse the genomic regions associated with two fundamental traits displaying important differentiation between evergreen versus deciduous birds as well as between urban versus rural birds, timing of breeding and personality.
Why is it all exciting?
The originality and strength of this project lay in the unique opportunity to develop refined analyses of selection in the wild in a multi-site setting for a vertebrate living in a well characterized heterogeneous habitat. Its main asset is the availability of long term phenotypic and genetic data. Its ambition is to create a textbook example to improve our understanding of the dynamics of selection in space and time.