| Summary: | As biodiversity continues to be lost at an alarming rate, it has become increasingly important to resolve issues surrounding taxonomic uncertainty and how best to prioritize populations for conservation. Controversy can arise over whether populations merit conservation if their taxonomic status is unclear. Additionally, maintaining intraspecific genetic diversity is of particular importance for preserving evolutionary history and the potential for future adaptation. In order to effectively protect this diversity, species and units below the species level need to be defined. However, delineation of such units is subject to many challenges, with no one strategy applying universally across taxa. Using mitochondrial DNA sequence and microsatellite genotypic data, I examine population structure and demographic history of Chrysemys picta bellii (western painted turtles) in British Columbia, where it is a species-at-risk. I use this system to compare the application of evolutionarily significant unit and management unit criteria with Canadian designatable unit guidelines to determine appropriate conservation units. I find that that BC western painted turtles form a single evolutionarily significant unit, with each occupied site constituting a separate management unit. These findings contrast with the evidence for six discrete designatable units. Patterns of genetic variation in BC western painted turtles indicate that the conservation of each region is important to maintaining regional diversity and evolutionary novelty.
I also address the taxonomic uncertainty in Chrysemys, which is ambiguous due to questions regarding whether the four regional morphological variants warrant formal recognition. Despite using both mitochondrial and nuclear sequence data, I do not find genetic evidence to conclusively resolve the taxonomic uncertainty in Chrysemys, however, there are indications that the two currently recognized species Chrysemys dorsalis and Chrysemys picta may be warranted.
Overall, this research presents the first detailed population genetic study for this species, which can be used to directly inform conservation prioritization of western painted turtles in BC. Moreover, the range-wide phylogeographic analyses is the most through genetic investigation of Chrysemys taxonomy to date, yet future research involving additional nuclear markers is still warranted.
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