North America is home to nearly half of the 640 known species of freshwater crayfish in the world. Nearly one third of those endemic to the United States are at risk of extinction due to increasing anthropogenic pressures (e.g., habitat fragmentation, water pollution, etc.). The epicenter of crayfish diversity is located here, in the southeastern United States, with over 68 species native to the state of Georgia. Despite the high crayfish diversity in this region, little is known regarding the distributions, genetic diversity and population structure of many of these indigenous crayfish. In this study, the genetic structure and phylogeography of three crayfish species native to the coastal plains and barrier islands of Georgia (Procambarus lunzi, P. advena and P. talpoides) were investigated. Given their restricted dispersal abilities, fragmented habitat and intolerance to saline waters, it was hypothesized that these species will exhibit significant population structure and low genetic diversity, possibly corresponding to specific barrier islands and/or major river drainages (e.g., Ogeechee and Satilla Rivers) of the area. To test this, the genetic diversity and population structure of these species was investigated via sequence analysis of the mitochondrial cytochrome c oxidase subunit (COI) gene. Preliminary data from P. talpoides suggests low levels of gene flow, significant levels of genetic differentiation and the possibility of a “cryptic species complex”. Considering their similar distributions, life history modes and habitat uses, similar patterns of genetic structure and isolation are expected for P. lunzi and P. advena. The possible identification of multiple cryptic species complexes from these species may suggest that the crayfish diversity of coastal Georgia is vastly underestimated and have significant implications for conservation and management of not only these species, but all crayfishes found throughout the southeastern United States.

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