Strong Population Structure and Differentiation within and among Burrowing Bog Crayfish Species of Southern Alabama Wetlands

Abstract

Despite their high diversity and degree of endemism in the southeastern US, little is known about population genetic structure of most crayfishes. This is because of their cryptic morphology and elusive behavior, particularly burrowing species. We compared population genetic structure of 2 burrowing crayfish species (Creaserinus burrisi and C. byersi) from bogs in Washington, Baldwin, and Mobile counties in southern Alabama, USA. Through hand excavation of burrows, we collected individuals from 7 drainage systems, with C. byersi in the southern extent and C. burrisi in the northern extent of the study area. Based on mitochondrial cytochrome oxidase subunit I (COI) gene sequences, tests of pairwise genetic structure approached the upper limit of 1.0, showed that haplotype sharing between and within drainages was nearly non-existent. Large differentiation between and low genetic diversity both between and within drainage systems occurred for both species. Genetic structuring corresponded to subtle hydrologic features such as fine-scale drainage patterns and human development (road crossings). Our data suggest that these species have recently diverged with extremely low vagility and rare dispersal events, resulting in isolated populations. Such population uniqueness from a genetic perspective pose considerable challenges to range-wide management of these and other similar species.