Assessing the impact of low-head dams and life history on fine scale genetic structure of three etheostomatine darters (Percidae)

Anthropogenic modifications to aquatic habitats, such as dams, can fragment lotic systems, disrupt fluvial continuity and modify flow patterns. Such structures could negatively impact riverine ecology and potentially act as barriers to gene flow. Although previous studies have examined potential negative effects of aquatic barriers on population structure and gene flow, most have focused on large species of fish that are highly vagile and have low habitat specificity. In addition, past studies have shown there is often a correlation between life history characteristics and gene flow in fish. This study will test the influence of dams and life history variation on fine scale genetic structure of Etheostomatine darters (Ammocrypta beanii, Etheostoma swaini, and Percina nigrofasciata) in the Pearl River basin. Individuals of all three species also were analyzed from three control sites (no dams) in the neighboring Tangipahoa River basin.;A minimum of thirty specimens were sampled from a total of twelve sites across both basins. These data suggest that the dams impacted the spatial genetic structure of each species differently. There was no genetic differentiation among populations of Ammocrypta beanii, a main channel, highly vagile species, above and below the two low head dams, whereas E. swaini and P. nigrofasciata displayed large and moderate amounts of genetic structure, respectively, across this same area. These data suggests that life-history may play a greater role than the dams in shaping fine-scale genetic structure for these species.