Using DNA barcodes to review the taxonomy of water and pygmy shrews in Canada
LE3 .A278 2021
Bachelor of Science
The American water shrew (Sorex palustris Richardson, 1828) and the American pygmy shrew (S. hoyi Baird, 1857) have two or more distinct clades in North America. Sorex hoyi is divided into an Eastern and Western clade; S. palustris is divided into Boreal, Cordilleran and Eastern clades. Previous studies have used Cytochrome b sequence data from the mitochondrial genome to attempt to determine if the subspecies associated with these clades warranted species status. In this study, cytochrome oxidase subunit 1 sequence data are tested to see whether two putative species, the eastern water shrew (S. albibarbis [Cope, 1862]), and Thompson’s pygmy shrew (S. thompsoni [Baird 1858]), are supported as separate species from their respective species complexes. DNA sequences of Cytochrome oxidase were downloaded from Genbank, n=14 for S. palustris and n=23 for S. hoyi. These were then used for phylogenetic tree construction and pairwise distance comparisons. The results from the analysis found for S. palustris the Boreal and Eastern clades had bootstrap support of 98-100% as was a Kimura-2-Parameter (K2P) pairwise distances of 4.98%. For S. hoyi, bootstrap support was 93% for the western clade and 83% for the eastern clade with a distance of 2.23% between the clades. The Cytochrome oxidase data did provide support to the species status of S. albibarbis of the Eastern from S. palustris of the Boreal clade with indirect support for S. navigator of the Cordilleran clade. The sequence data did not have enough divergence or confidence for S. hoyi to support species status for S. h. thompsoni of the eastern clade.
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