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Among-individual diet variation within a lake trout ecotype: lack of stability of niche use.
  • +5
  • Louise Chavarie,
  • Kimberly Howland,
  • Les Harris,
  • Colin Gallagher,
  • Michael Hansen,
  • William Tonn,
  • Andrew Muir,
  • Charles Krueger
Louise Chavarie
Michigan State University
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Kimberly Howland
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Les Harris
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Colin Gallagher
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Michael Hansen
US Geological Survey Hammond Bay Biological Station
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William Tonn
University of Alberta
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Andrew Muir
Great Lakes Fishery Commission
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Charles Krueger
Michigan State University
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Abstract

In a polymorphic species, stable differences in resource use are expected among ecotypes, and homogeneity in resource use is predicted within an ecotype. Yet, using a broad resource spectrum has been identified as a strategy for fishes living in unproductive northern environments, where food is patchily distributed and ephemeral. We investigated whether individual specialization of trophic resources occurred within the generalist piscivore ecotype of lake trout from Great Bear Lake, Canada, reflective of a form of diversity. Four distinct dietary patterns of resource use within the lake trout ecotype were detected from fatty acid composition, with some variation linked to spatial patterns within Great Bear Lake. Feeding habits of different groups within the ecotype were not associated with detectable morphological or genetic differentiation, suggesting that behavioral plasticity caused the trophic differences. A low level of genetic differentiation was detected between exceptionally large-sized individuals and other individuals. Investigating a geologically young system that displays high levels of intraspecific diversity and focusing on individual variation in diet suggested that individual trophic specialization can occur within an ecotype. The characterization of niche use among individuals, as done in this study, is necessary to understand the role that individual variation can play at the beginning of differentiation processes.

Peer review status:UNDER REVIEW

29 Jul 2020Submitted to Ecology and Evolution
31 Jul 2020Assigned to Editor
31 Jul 2020Submission Checks Completed
04 Aug 2020Reviewer(s) Assigned