Range-wide Phylogeography of Blanding's Turtle (Emys blandingii)
Abstract
Phylogeography analyses have proven to be an effective method for determining the pattern and processes of genetic diversification across a species’ geographic range. Understanding the genetic lineages and evolutionary history of a species can provide insight to current and future conservation and management actions. The Blanding’s Turtle, Emys blandingii, is a long-lived species with a relatively narrow distribution centered in the upper Midwest and Great Lakes region. It is listed as endangered or threatened throughout most of its range mainly due to habitat loss. Previous molecular work on this species, using mitochondrial DNA and microsatellites has generated distinct hypotheses concerning the number of evolutionary significant units and history of lineage diversification. The purpose of my study was to use nuclear DNA in order to observe variation, determine population demography based on variation and glacial history, and to test withstanding phylogeographic hypotheses. A total of 55 individuals were haplotyped from 26 different populations across the species’ range. Genetic variation was determined by the number of single nucleotide polymorphisms (SNPs) found in 1638 base pairs combined from three nuclear loci. Overall, a total of 23 different haplotypes were identified, along with low nucleotide diversity. Population analyses showed support for two main lineages which is in agreement with one of the current hypotheses based on microsatellite analysis (Mockford et al. 2007). Demographic analyses showed some support of range expansion following glacial retreat. Low population differentiation shows that there is a need to look at additional nuclear loci in order to gain a larger number of SNPs to better determine evolutionary significant units and resolve glacial effects on this species. For now, conservation efforts should take into consideration the low genetic diversity of this species’ main range and protect the disjunct that are genetically differentiated as evidenced by this study and others.
Degree
M.S.
Advisors
Jordan, Purdue University.
Subject Area
Genetics|Conservation
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