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

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dc.contributor.advisor Johansen, Rebecca Blanton
dc.contributor.author Grubb, Brooke
dc.contributor.other Department of Biology
dc.date.accessioned 2020-01-15T19:51:32Z
dc.date.available 2020-01-15T19:51:32Z
dc.date.issued 2020
dc.identifier.other OCLC #1136490105
dc.identifier.uri http://hdl.handle.net/20.500.11989/6642
dc.description.abstract Habitat loss and fragmentation represent significant threats to North American crayfish diversity. Assessments of genetic diversity within and among populations of imperiled species can provide a baseline for determining the relative impacts of contemporary anthropogenic threats such as habitat fragmentation to population connectivity, as well as aid in identifying historical factors that contribute to population structure. Cambarus pristinus, a species of conservation concern and a headwater-stream adapted crayfish endemic to the Cumberland Plateau in Tennessee, exhibits a disjunct distribution within 4th order or lower tributaries of the Caney Fork and Big Brush Creek systems and is comprised of two morphologically distinct forms, the nominal Caney Fork form (Caney Fork system) and the Sequatchie form (Caney Fork and Big Brush Creek systems). Habitat degradation from activities such as silviculture and strip mining have been observed throughout the Cumberland Plateau and Cambarus pristinus has experienced recent local extirpations. Our objectives were to examine variation in mitochondrial DNA (COI) and nuclear alleles (microsatellites) to provide estimates of phylogeographic relationships and contemporary levels of genetic structure, respectively, within C. pristinus. We predicted that changes in stream hydrology, physiographic regions, and drainage divides would contribute to long-standing isolation among populations separated by these features. We also expected recent anthropogenic disturbances and population loss to have further impacted population connectivity and lead to reduced genetic diversity and increased population isolation relative to historic levels. Assessment of variation in mitochondrial haplotypes and phylogeographic relationships found low haplotype divergences and broadly shared haplotypes within each morphological form, implying that gene flow was maintained among populations within a form at some level historically, and that geographic features and natural instream barriers did not prevent dispersal. Each form had a unique set of haplotypes and was recovered as a separate, divergent clade indicating the two forms represent distinct genetic lineages and supporting recognition of the Sequatchie form as a distinct taxon. For the Caney Fork form of C. pristinus our microsatellite data recovered a high degree of population isolation and support for the occurrence of six isolated populations. We also recovered several low genetic diversity metrics within each cluster and for the Caney Fork form overall. This suggests that the Caney Fork form of C. pristinus has a reduced adaptive potential and that historic connectivity has been lost under anthropogenic disturbance. We suggest that Cambarus pristinus warrants continued state protection and that future population genetic monitoring be implemented.
dc.publisher Austin Peay State University
dc.subject.lcsh Cambarus -- Effect of habitat modification on -- Sequatchie River Watershed (Tenn.)
dc.subject.lcsh Crayfish -- Effect of habitat modification on -- Sequatchie River Watershed (Tenn.)
dc.subject.lcsh Cambarus -- Effect of habitat modification on -- Caney Fork River (Tenn.)
dc.subject.lcsh Crayfish -- Effect of habitat modification on -- Caney Fork River (Tenn.)
dc.subject.lcsh Extinction (Biology)
dc.subject.lcsh Silvicultural systems
dc.title Phylogeography and population genetics of a headwater-stream adapted crayfish, "Cambarus pristinus" (Decapoda: Cambaridae), from the Cumberland Plateau in Tennessee en_US
dc.date.updated 2020-01-07T20:49:23Z
dc.language.rfc3066 en


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