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Challenge to the model of lake charr evolution: Shallow- and deep-water morphs exist within a small postglacial lake

November 21, 2016

All examples of lake charr (Salvelinus namaycush) diversity occur within the largest, deepest lakes of North America (i.e. > 2000 km2). We report here Rush Lake (1.3 km2) as the first example of a small lake with two lake charr morphs (lean and huronicus). Morphology, diet, life history, and genetics were examined to demonstrate the existence of morphs and determine the potential influence of evolutionary processes that led to their formation or maintenance. Results showed that the huronicus morph, caught in deep-water, had a deeper body, smaller head and jaws, higher eye position, greater buoyancy, and deeper peduncle than the shallow-water lean morph. Huronicus grew slower to a smaller adult size, and had an older mean age than the lean morph. Genetic comparisons showed low genetic divergence between morphs, indicating incomplete reproductive isolation. Phenotypic plasticity and differences in habitat use between deep and shallow waters associated with variation in foraging opportunities seems to have been sufficient to maintain the two morphs, demonstrating their important roles in resource polymorphism. Rush Lake expands previous explanations for lake charr intraspecific diversity, from large to small lakes and from reproductive isolation to the presence of gene flow associated with strong ecological drivers.

Publication Year 2016
Title Challenge to the model of lake charr evolution: Shallow- and deep-water morphs exist within a small postglacial lake
DOI 10.1111/bij.12913
Authors Louise Chavarie, Andrew M. Muir, Mara S. Zimmerman, Shauna M. Baillie, Michael J. Hansen, Nancy A. Nate, Daniel L. Yule, Trevor Middel, Paul Bentzen, Charles C. Krueger
Publication Type Article
Publication Subtype Journal Article
Series Title Biological Journal of the Linnean Society
Index ID 70178481
Record Source USGS Publications Warehouse
USGS Organization Great Lakes Science Center