Research Document 2020/051

River Darter (Percina shumardi) mitochondrial DNA haplotype diversity across COSEWIC National Freshwater Biogeographic Zones

By Reid, S. M., Haxton, T., and McCarthy, A.

Abstract

River Darter (Percina shumardi) is a small, benthic fish that is a member of the perch family (Percidae). In Canada, the species has a continuous distribution through most of Manitoba into northwestern Ontario in the Saskatchewan-Nelson drainage as well as the Hudson Bay drainage west of James Bay. River Darter is also found in Lake St. Clair and its tributaries in southwestern Ontario. Based on evidence of discreteness and evolutionary significance, groups of populations can be assessed by COSEWIC as separate Designatable Units (DUs). For freshwater fishes, the delineation of DUs has been informed using COSEWIC National Freshwater Biogeographic Zones (NFBZ) and population genetic structure. Based on a three DU structure, COSEWIC assessed the status of the River Darter as Not at Risk in the Saskatchewan–Nelson River (DU1) and Southern Hudson Bay–James Bay (DU2) zones and Endangered in the Great Lakes – Upper St. Lawrence (DU3) zone. In this study, haplotype data from two mitochondrial DNA genes (cytochrome-b [cyt-b] and cytochrome oxidase subunit 1 [CO1]) were used to assess whether River Darter population genetic structure corresponds with the three NFBZ. The assessment was based on: (i) the distribution of private and shared haplotypes; (ii) phylogenetic relationships among haplotypes; and, (iii) distance- and ordination-based tests of haplotype structure. One hundred-forty-nine sequences from both mitochondrial DNA genes were used in the analysis, representing River Darter from 14 waterbodies. Overall, 29 cyt-b haplotypes and eleven CO1 haplotypes were identified.  Based on private haplotypes, the cyt-b minimum spanning network, and Principal Coordinate Analysis (PCoA) of cyt-b and CO1 haplotype data, differentiation among River Darter populations was greatest between DU3 and the two western DUs. Private haplotype data and PCoA (cyt-b only) provide some evidence of differentiation between DU1 and DU2. These interpretations are largely influenced by samples from two waterbodies: Lake Badesdawa (DU2) and the Thames River (DU3). Samples from additional populations within DU2 are required for more robust support of the existing DU structure.

Research Document 2020/051 (PDF, 717 KB)

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