Osteological evidence of genetic divergence of lake trout (Salvelinus namaycush) in Lake Superior

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Three phenotypes of Salvelinus namaycush in Lake Superior, the lean, siscowet, and bumper, are traditionally identified primarily by fat content and body shape. Their taxonomic status is in question because of intermediates as well as the possibility that the diagnostic characters are ecophenotypic. Two osteological characters, the dorsal opercular notch (first recorded by Agassiz in his description of the siscowet) and radii on the anterodorsal part of the supraethmoid, differ between most leans and siscowets. The notch in the opercle near its articulation with the hyomandibular bone is present in humpers, usually present in siscowets, and usually absent in leans. Radii on the anterodorsal surface of the supraethmoid bone usually are found in siscowets and humpers but usually are absent in leans. The correlations among these characters and other features of the phenotype indicate a significant level of differentiation between the three phenotypes. Available evidence suggests that the differentiation is genetic. The frequency of mixed phenotypes is evidence of limited gene flow among the phenotypes. The siscowet and humper phenotypes apparently originated in Lake Superior in postglacial time.

Publication type Article
Publication Subtype Journal Article
Title Osteological evidence of genetic divergence of lake trout (Salvelinus namaycush) in Lake Superior
Series title Copeia
DOI 10.2307/1446708
Volume 1994
Issue 4
Year Published 1994
Language English
Publisher American Society of Ichthyologists and Herpetologists
Contributing office(s) Great Lakes Science Center
Description 8 p.
First page 843
Last page 850
Online Only (Y/N) N
Additional Online Files (Y/N) N
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