Supervised by:

Guillaume de Lafontaine (Regular member)

Research project description

Genomic signature of migration in three boreal conifers

IntroductionSpecies are expected to move towards the northern limit under climate change. The potential of a species to colonize habitats that become favourable is determined by dispersal ability. For trees, it has been hypothesized that such natural spread will not be fast enough to allow current populations to follow areas with optimal climatic conditions, which will continue to pose a serious threat to boreal ecosystems. However, evolutionary dynamics at the range limit may favour the rapid spread of trees into new favourable habitats when long-distance dispersal events occur. These events (corresponding to founder effects) would allow the formation of new populations with abundant local distribution. ObjectivesIn this study, three conifer species, white spruce (Picea glauca), black spruce (Picea mariana), and larch (Larix laricina), will be compared to see if post-glacial colonisation and subsequent expansion have resulted in a decrease in genetic diversity and increase in genetic differentiation along the colonisation front. Study sitesThis study is spread out along a latitudinal gradient from Mont-Laurier to Rivière Boniface (Nunavik) with a total of 14 sites, spaced 150 to 200 kilometres apart, in order to show the northern temperate and boreal zones. One site each will be located at Mont-Laurier, the Vérendrye Wildlife Reserve, Amos, Matagami, Waskaganish, Eastmain, Chisasibi and Wemindji, while two sites each will be located at Kuujjuarapik, Umiujaq and Rivière Boniface. Material and methodsThe study will be conducted on three conifer species: white spruce (Picea glauca), black spruce (Picea mariana) and larch (Larix laricina). For each of the 14 sites, 15 individuals of each species will be studied. A DNA extraction based on the year's sprout will then be performed in the laboratory. All individuals will be genotyped using a high-throughput sequencing genotyping approach (DarT-seq). The various steps of digestion, amplification, sequencing and construction of a library by bioinformatics will be carried out by the Diversity Arrays Technology Laboratory of the University of Canberra in Australia. The structure of the neutral genetic diversity of natural populations along the colonization route will be determined and compared, as well as the adaptive genetic diversity according to the environment. This will allow the determination of the processes of isolation by distance and isolation by environment. ReferencesGamache, I., Jaramillo‐Correa, J. P., Payette, S., & Bousquet, J. (2003). Diverging patterns of mitochondrial and nuclear DNA diversity in subarctic black spruce: imprint of a founder effect associated with postglacial colonization. Molecular Ecology, 12(4), 891-901.