Speaker
Description
Almost all organisms have geographical distributions that are limited by range margins. But why? What prevents the evolution of local adaptation in populations at a range margin from allowing the species to expand its range into new territory? One idea is that marginal populations are small and genetically depauperate, with limited potential for local adaptation. Gene flow into such populations would then increase their adaptive potential, effectively providing them the equivalent of evolutionary rescue and enabling further geographic spread. Another idea is that migration into range margins may bring maladaptive alleles compromising the performance of marginal populations and the species’ potential for adaptation and expansion – the opposite of evolutionary rescue. Knowledge on the evolutionary drivers of adaptation across environments not only helps understand range limits but is also key to understand and predict the evolutionary responses of populations facing environmental changes. With EcoRaMa project, we aim to test these two hypotheses using an annual plant, Mercurialis annua, as a model species. M. annua has a distribution ranging from the Mediterranean basins to norther Europe. In 2023, we established experiment populations subject to different scenarios of admixture in 11 gardens across its range and beyond its range margins. We follow the possible evolution of these populations for four years between 2023 and 2027, corresponding to six to eight generations for M. annua. In this poster, we present empirical evidence on climatic adaptation across the range of M. annua in various life history and morphological traits. We also present preliminary results from the first generation showing the importance of germination behavior for influencing demographic performance among populations and experimental gardens.