Population genetic study of the US federally listed Illinois cave amphipod, Gammarus acherondytes

Worldwide, conservation personnel must balance the needs of endangered species and humans. Studies that provide information of a species' genetic structure can identify conservation units and help prioritize populations. We used a region of the cytochrome c oxidase subunit I gene to examine the population genetics of the U.S. federally listed Illinois cave amphipod, Gammarus acherondytes. Eleven unique haplotypes were identified from nine populations in two hydrologically separate subregions, each of which contained genetically distinct populations. This conclusion is based on (i) subregions form clades in the interspecific phylogeographic analyses; (ii) the between-subregions component in the Analysis of Molecular Variance accounted for a significant fraction (81.45%) of the genetic variation; and (iii) no haplotypes were shared between subregions. These results coincide with the known distribution of G. acherondytes and regional hydrology. We recommend future recovery efforts avoid mixing individuals between subregions to prevent the breakdown of local adaptive gene complexes.