Genetic studies Across North America: Total evidence approach - Species identification - lake comparisons- Lake Erie Structure
Osvaldo J. Sepulveda Villet, Alexander M. Ford, James D. Williams, and Carol A. Stepien
Abstract: Great Lakes populations of Yellow Perch have fluctuated throughout past decades to the present due to unstable recruitment patterns and exploitation. Our study analyzes genetic diversity and structure across the native range in order to interpret phylogeographic history and contemporary patterns. We compare complete mitochondrial DNA control region sequences (912 base pairs) from 568 spawning individuals at 32 sites, encompassing all 5 Great Lakes and outlying watersheds from the upper Mississippi River, Lake Winnipeg, Lake Champlain, and Atlantic and Gulf coastal relict populations. These broad-scale divergences additionally are compared with fine-scale patterns from 334 individuals at 16 spawning sites across Lake Erie’s 4 fishery management units. We identify 21 mtDNA haplotypes, including a widespread type that totals 87% of individuals across the Great Lakes. Overall genetic diversity is relatively low in comparison with other Great Lakes fishes, congruent with prior allozyme and microsatellite studies. The largest genetic demarcation separates 2 primary population groups: one in the Great Lakes, Lake Winnipeg, and upper Mississippi River watersheds and the other along the Atlantic and Gulf coasts, together with Lake Champlain; which diverged ~365,000 years ago. In addition, the watersheds house genetically separable groups, whose patterns reflect broad-scale isolation by geographic distance. A few spawning groups show some fine-scale differentiation within Lake Erie, which do not reflect fishery management units and need further study with higher-resolution markers.
Fig. 1. Maps showing (a) the native distribution of Yellow Perch Perca flavescens (shaded; adapted from Lee et al. 1980), our sampling sites (lettered according to Table 1), distribution of Yellow Perch mtDNA control region haplotypes among the sites, and hypothesized colonization pathways from glacial refugia (arrows, adapted from Mandrak and Crossman 1992), (b) sampling sites in Lake Erie, with boundaries of Lake Erie management units.
Fig. 2. Neighbor-joining tree (Saitou and Nei 1987) of Kimura (1980) 2-parameter genetic distances showing relationships among Yellow Perch mtDNA haplotypes, rooted to Eurasian Perch and constructed in Mega (Tamura et al. 2007). Percentages denote nodal support from 1000 bootstrap pseudoreplicates. Pairwise genetic distance bar is calibrated at 2% per million year. * = most common haplotypes (1, 2) that are most widely distributed. Vertical bars denote primary geographical regions.
A
B
Fig. 3. Mantel (1967) pairwise test for relationship between genetic distance (θST/1- θST) and geographical distance (km) among Yellow Perch sampling sites. (a) Across North American sites; p = 0.003**, R2 = 0.413, y = 0.0002 (km) + 0.1609. (b) Across Lake Erie: p = 0.604 (NS), R2 = 0.046. y = 0.00005 (km) + 0.0434.
Genetic studies Across North America: Total evidence approach - Species identification - lake comparisons - Lake Erie Structure
