Life at the leading edge: genetic impoverishment of the spotted bass, Micropterus punctulatus, at its Western edge

Genetic variation was evaluated for spotted bass (Micropterus punctulatus) at the edge of the species native range in central Texas. We analyzed mitochondrial D-Loop sequences from 64 individuals representing nine sites within the Brazos and Trinity River watersheds. Our primary objectives were to 1) compare the genetic diversity of spotted bass in central Texas to genetic diversity estimates of conspecifics in other geographic regions and to other species from similar geographic regions, to 2) determine whether there was evidence for within or between drainage genetic structure, and to 3) test whether the D-Loop sequence was a reliable marker for discriminating among native and introduced Texas micropterids. Genetic diversity was low relative to sympatric micropterids, as well as for the marker in general, but our results are similar to patterns observed for this species in Oklahoma and fit with broader multi-species patterns observed for this geographic area. AMOVA, SAMOVA, and isolation by distance analyses provided evidence that genetic differentiation exists among population groups. The sequence data suggests the D-Loop would be useful for discriminating among M. floridanus, M. salmoides, and M. dolomieu, but not among M. punctulatus, M. coosae, M. henshalli, and M. treculii.