French Canadian Ancestry in Quebec Shaped by Local Topographies, Says Data Study

Combining a comprehensive dataset – including marriage documents – compiled from more than 4 million Catholic parish records with genotype data for more than 22,000 French and French Canadian individuals, researchers have conducted a novel analysis of French Canadian ancestry in Quebec, Canada, since the 17^th Century. While most other population genetic models provide only coarse representations of a region's real-world ancestry, this new approach reveals detailed insights into historic European colonization, migration, and settlement patterns, reflecting intricate French Canadian population structures within geographic constraints. What's more, using the combined datasets, Anderson-Trocmé et al. developed a freely accessible simulated whole-genome sequence dataset with spatiotemporal metadata for more than 1.4 million individuals, enabling future researchers to investigate Quebec's population genetics at an unprecedented resolution. The migration and dispersal of humans across geographic landscapes can be reconstructed through population genomic analyses. However, for most models, discerning the relationship between spatial migrations and continuous genetic variation within a given population has been difficult and occasionally misleading. Luke Anderson-Trocmé and colleagues leveraged a population-scale spatial pedigree compiled from 4 million historical parish records from across Quebec and genotype data from 2276 French and 20,451 French Canadian individuals to finely model French Canadian ancestry – and how it was shaped by the region's geographic features. Anderson-Trocmé et al. found that most individuals in Quebec derive ancestry from ~8500 settlers who migrated from France in the 17^th and 18^th centuries and that the first 2600 French colonizers contributed two-thirds of the French Canadian gene pool. What's more, the authors show that geographic features, particularly its river networks, considerably shaped Quebec's population structure, defining major axes of migration and genetic relatedness.