Phylogeography and population genetics of a headwater-stream adapted crayfish, Cambarus pristinus (Decapoda: Cambaridae), from the Cumberland Plateau in Tennessee

Abstract

Assessments of genetic diversity for imperiled species can provide a baseline for determining the relative impacts of contemporary anthropogenic threats (e.g., habitat fragmentation) on population connectivity and identifying historical factors contributing to population structure. We conducted a population genetics and phylogeographic assessment of the imperiled Pristine Cray sh (Cambarus pristinus) sampled throughout its range encompassing two morphologically distinct forms. Pristine Cray sh exhibit a disjunct distribution throughout lower order tributaries suggesting they are headwater-adapted species. The two morphologically distinct forms of the Pristine Cray sh are found in the upper Caney Fork (nominal Caney Fork form) and the Big Brush Creek and Cane Creek systems (Sequatchie form). We used 19 microsatellite loci and the cytochrome oxidase subunit I (COI) gene to assess population connectivity and genetic diversity of the Pristine Cray sh. Haplotypes recovered from the COI gene revealed that historic connectivity was maintained within each form of the Pristine Cray sh. However, the divergence between forms was high (2.3%), suggesting each form is on an independent evolutionary trajectory, which supports recognition of the Sequatchie form as a distinct taxon. Microsatellite analyses for the Caney Fork form recovered a high degree of population isolation and support for six genetically isolated population. In addition, genetic diversity metrics per population and for the Caney Fork form were low suggesting that the Caney Fork form is at an increased risk of extinction under anthropogenic disturbances. We suggest that each form receive continued listing protection and conservation resources and that the Sequatchie form be treated as a unique taxon.Table 1 Collection information and number of individuals of C. pristinus captured. Form refers to the morphological form of C. pristinus, site ID refers to the assigned site number used in subsequent tables and gures, stream denotes the stream name, county refers to the county where sampling efforts occurs, date collected refers to when each sampling effort occurred, and # captured represents the number of tissue samples recovered from all sampling efforts. A "+" denotes new localities identi ed and sampled for C. pristinus. FormSite ID Stream County Date Collected Latitude Longitude No.