Retracer le changement de la répartition géographique d’une espèce grâce aux événements d’hybridation in situ
Shifts in the geographical distribution of species are strongly influenced by climate change. In areas where conditions become unfavorable, demographic decline precedes the extinction of a species. During this decline, hybridization events may occur when individuals of a scarce species breed with more abundant heterospecific indivduals (Hubbs principle). A previous study in Southern Quebec (Canada), detected several in situ hybridization events involving females Chrosomus neogaeus and males Chrosomus eos, although C. neogaeus is nearly absent from the region. This has been achieved thanks to the asexual reproduction mode of hybrids which then preserve the genetic diversity of parental species intact. This study aimed to assess the demographic changes of C. neogaeus according to the geographic pattern of hybridization events. A large latitudinal sampling was performed to determine the geographical distribution of members of the C. eos-neogaeus complex and test different biogeographical scenarios. While C. neogaeus was present across all drainage basins sampled, a correlation between drainages and the glacial origin of individuals that colonized them revealed different postglacial colonization histories. However, a latitudinal gradient was observed regarding the hybrid diversity. In the south, results revealed a large occurrence of in situ hybridizations, but these became less common going north. This latitudinal pattern could be interpreted as a northward shift in the C. neogaeus geographical distribution and constitutes additional evidence of a large-scale environmental change in freshwater aquatic ecosystems since the end of glaciation.
Méné ventre citron Chrosomus neogaeus Complexe Chrosomus eos-neogaeus Demographic changes Hybridization events Geographical distribution Climatic changes Finescale dace Chrosomus neogaeus Chrosomus eos-neogaeus complex