Influence of Forest Road Culverts and Waterfalls on the Fine Scale Distribution of Brook Charr (Salvelinus fontinalis) Genetic Diversity in a Boreal Watershed

The aim of this study was to evaluate the effect of artificial and natural barriers to fish movement on the fine scale distribution of genetic diversity in brook charr (Salvelinus fontinalis). We genotyped 995 individuals sampled from 25 locations in a boreal watershed fragmented by culverts and natural waterfalls. Using a landscape genetic approach, we tested whether the presence of both types of barriers resulted in decreased genetic diversity and increased divergence within isolated locations. Results showed that genetic divergence was enhanced between sites separated by barriers and genetic diversity was reduced within sites located above barriers. Overall, results of this study suggested that the effects of culverts and natural waterfalls were similar but the effect of culverts was globally more pronounced. To our knowledge, this is the first study illustrating the effects of forest-road culverts and natural waterfalls on the distribution of genetic diversity in brook charr within a boreal watershed. We discuss our results in the context of boreal forest-road network expansion and in light of the necessity for a better understanding of the potential impact of road infrastructure on long-term fish population persistence.