Temporal dynamics of migration-linked genetic variation are driven by streamflows and riverscape permeability

The permeability of landscapes is often explored spatially, but may also vary across time. For example, highways are more passable with low traffic, and mountain landscapes are more passable once snow-free. Landscape permeability especially influences migratory animals. Partial barriers are features that are passable in some conditions. Partial barriers are common in rivers due to the two-dimensional nature of river networks: aquatic organisms cannot circumvent in-river barriers. Barriers in river networks include waterfalls, logjams, or culverts, all of which vary in permeability depending on streamflow. We explore the influence of partial barriers on the spatial and temporal distribution of migration-linked genotypes of fish in tributaries to the South Fork Eel River, California, USA. We study Oncorhynchus mykiss, a salmonid fish with co-occurring resident and migratory forms. We genotyped >3,000 individuals using RAD-capture and classified individuals as resident, heterozygous, or...