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

Biological Journal of the Linnean Society
By: , and 

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Abstract

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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Challenge to the model of lake charr evolution: Shallow- and deep-water morphs exist within a small postglacial lake
Series title Biological Journal of the Linnean Society
DOI 10.1111/bij.12913
Edition Online First
Year Published 2016
Language English
Publisher Wiley
Contributing office(s) Great Lakes Science Center