Experimental evidence for reduced hybrid viability between dwarf and normal ecotypes of lake whitefish (Coregonus clupeaformis Mitchill)

G. Lu, L. Bernatchez

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

Forces driving the evolution of reproductive isolation among natural populations, as well as the mechanisms involved to maintain it, are still poorly understood. Because sympatric fish ecotypes mainly differ in phenotypic traits associated with occupying distinct trophic niches, it is generally believed that reproductive isolation is mainly driven by ecological divergent selection, excluding genome incompatibility as a basis for postmating isolation. We performed cross experiments between dwarf and normal ecotypes of lake whitefish (Coregonus clupeaformis Mitchill) originating from distinct glacial refugia to test the hypothesis that their geographical isolation during the Pleistocene may have led to sufficient genetic divergence for the development of reproductive isolation between them before their secondary contact. Similar fertilization success in pure and hybrid crosses indicated the absence of gametic incompatibility between the two ecotypes. In contrast, daily embryonic mortality rates were 2.4-4.7 times higher in reciprocal hybrid crosses compared to pure crosses, which supports our working hypothesis. These results, along with previous morphological and population genetic studies, indicate that both genetic and ecological mechanisms may jointly act to promote speciation among northern freshwater fish ecotypes.

Original languageEnglish (US)
Pages (from-to)1025-1030
Number of pages6
JournalProceedings of the Royal Society B: Biological Sciences
Volume265
Issue number1400
DOIs
StatePublished - Jun 7 1998

Fingerprint

Ecotype
Salmonidae
Coregonus clupeaformis
ecotype
Reproductive Isolation
Lakes
ecotypes
Fish
reproductive isolation
viability
incompatibility
lake
Fishes
Genes
secondary contact
embryonic mortality
Population Genetics
fish
fertilization (reproduction)
refugium

Keywords

  • Coregonus
  • Ecotypes
  • Fish
  • Hybrids
  • Reproductive isolation
  • Speciation

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

Cite this

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AU - Bernatchez, L.

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N2 - Forces driving the evolution of reproductive isolation among natural populations, as well as the mechanisms involved to maintain it, are still poorly understood. Because sympatric fish ecotypes mainly differ in phenotypic traits associated with occupying distinct trophic niches, it is generally believed that reproductive isolation is mainly driven by ecological divergent selection, excluding genome incompatibility as a basis for postmating isolation. We performed cross experiments between dwarf and normal ecotypes of lake whitefish (Coregonus clupeaformis Mitchill) originating from distinct glacial refugia to test the hypothesis that their geographical isolation during the Pleistocene may have led to sufficient genetic divergence for the development of reproductive isolation between them before their secondary contact. Similar fertilization success in pure and hybrid crosses indicated the absence of gametic incompatibility between the two ecotypes. In contrast, daily embryonic mortality rates were 2.4-4.7 times higher in reciprocal hybrid crosses compared to pure crosses, which supports our working hypothesis. These results, along with previous morphological and population genetic studies, indicate that both genetic and ecological mechanisms may jointly act to promote speciation among northern freshwater fish ecotypes.

AB - Forces driving the evolution of reproductive isolation among natural populations, as well as the mechanisms involved to maintain it, are still poorly understood. Because sympatric fish ecotypes mainly differ in phenotypic traits associated with occupying distinct trophic niches, it is generally believed that reproductive isolation is mainly driven by ecological divergent selection, excluding genome incompatibility as a basis for postmating isolation. We performed cross experiments between dwarf and normal ecotypes of lake whitefish (Coregonus clupeaformis Mitchill) originating from distinct glacial refugia to test the hypothesis that their geographical isolation during the Pleistocene may have led to sufficient genetic divergence for the development of reproductive isolation between them before their secondary contact. Similar fertilization success in pure and hybrid crosses indicated the absence of gametic incompatibility between the two ecotypes. In contrast, daily embryonic mortality rates were 2.4-4.7 times higher in reciprocal hybrid crosses compared to pure crosses, which supports our working hypothesis. These results, along with previous morphological and population genetic studies, indicate that both genetic and ecological mechanisms may jointly act to promote speciation among northern freshwater fish ecotypes.

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