Spatial population structure of a widespread aquatic insect in the Colorado River Basin: Evidence for a Hydropsyche oslari species complex

AbstractStructural connectivity and dispersal ability are important constraints on functional connectivity among populations. For aquatic organisms that disperse among stream corridors, the regional structure of a river network can, thus, define the boundaries of gene flow. In this study, we used mitochondrial DNA (mtCO1 barcoding gene) to examine the genetic diversity and population structure of a caddisfly with strong dispersal capabilities, Hydropsyche oslari (Trichoptera:Hydropsychidae), in the topologically-diverse Colorado River Basin. We expected to find less genetic differentiation among populations of H. oslari within the Upper Basin, which has a dense dendritic network of perennial tributaries that allow for greater potential dispersal and gene flow, than among populations within the arid and sparse river network of the Lower Basin. We also expected to find genetic differentiation among H. oslari in the Upper and Lower Basins because contemporary populations are geographically distant from each ...