Sidewalk Plants as a Model for Studying Adaptation to Urban Environments
Résumé
As a widespread human-altered-habitat, urban environment represents a potentially interesting model for evolutionary ecologists to study contemporary adaptation face to global change. For plants, one of the most obvious characteristics of urban environment is fragmentation. Small patches around planted trees on sidewalks have been colonized by wild plants and represent a typical fragmented urban habitat. It also represents a geometrical and homogeneous habitat to study plant adaptation to fragmentation. Based on a ten year research program in French Mediterranean (Montpellier), we will discuss how plants have adapted to urban patches in the annual weed Crepis sancta (Asteraceae). While the most obvious traits expected to respond to fragmentation is seed dispersal traits, we will present results showing how urban patch have actually selected for a battery of life history traits and ecophysiological traits. The striking result is that adaptation is rapid in urban environment and can be detected in less than 15 generations. We will discuss to what extent such adaptation can be generalized to adaptation urban environment and how the comparison between rural and urban populations provides a powerful method to study how plants adapt to various facets of global change. Overall, urban environments has proved to be a manageable and relevant ecological model to study contemporary adaptation.