Research Publication Title

Investigating Cryptic Diversity in the Crayfish of Coastal Georgia

Major

Biology

Faculty Mentor

Dr. David Weese

Keywords

Population genetics, Mitochondrial DNA, Cryptic species

Abstract

North America is home to nearly half of the 640 known species of freshwater crayfish in the world. Unfortunately, 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 region of the United States with over 68 species native to the state of Georgia. Despite the high diversity of crayfish 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 species of crayfish native to the coastal plains and barrier islands of Georgia (Procambarus lunzi, P. advena and P. talpoides) will be investigated. Given their restricted dispersal abilities, fragmented habitat and intolerance to saline waters, it is hypothesized that these species will exhibit significant population structure and low levels of 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 will be 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 complex from these species may suggest that the crayfish diversity of coastal Georgia may be vastly underestimated and have significant implications for the conservation and management of not only these species, but all crayfishes found throughout the southeastern United States.

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Investigating Cryptic Diversity in the Crayfish of Coastal Georgia

North America is home to nearly half of the 640 known species of freshwater crayfish in the world. Unfortunately, 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 region of the United States with over 68 species native to the state of Georgia. Despite the high diversity of crayfish 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 species of crayfish native to the coastal plains and barrier islands of Georgia (Procambarus lunzi, P. advena and P. talpoides) will be investigated. Given their restricted dispersal abilities, fragmented habitat and intolerance to saline waters, it is hypothesized that these species will exhibit significant population structure and low levels of 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 will be 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 complex from these species may suggest that the crayfish diversity of coastal Georgia may be vastly underestimated and have significant implications for the conservation and management of not only these species, but all crayfishes found throughout the southeastern United States.