Rapid ecological speciation in three-spined stickleback Gasterosteus aculeatus from Middleton Island, Alaska: The roles of selection and geographic isolation

O. Gelmond, F. A. Von Hippel, M. S. Christy

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Morphological analysis of three-spined stickleback Gasterosteus aculeatus collected in Middleton Island, Alaska, was conducted in order to study how gene flow and selection interact during divergence. Middleton Island was uplifted by 3·4 m during the Great Alaska Earthquake in 1964; this event formed a series of new freshwater sites, triggering rapid evolution, and probably rapid speciation, in G. aculeatus populations that colonized them. The level of hybridization between the anadromous and the resident freshwater populations is reflected by the level of morphological variance of the resident freshwater G. aculeatus. Therefore, geographic isolation of the sites from the sea (approximating gene flow) and ionic concentration of the water (reflecting selection pressures) were correlated with morphological variance of the resident freshwater populations. Geographic isolation was negatively correlated with morphological variance in a majority of the analysed traits. Both selection and gene flow surrogates were found to be important influences on variance in morphology, though selection had a larger effect, especially on armour traits. It was concluded that gene flow appeared to constrain ecological speciation, but even in the presence of gene flow the strong selection in the freshwater environment was apparently leading to rapid divergence.

Original languageEnglish (US)
Pages (from-to)2037-2051
Number of pages15
JournalJournal of Fish Biology
Volume75
Issue number8
DOIs
StatePublished - Nov 2009
Externally publishedYes

Keywords

  • 1964 Great Alaska Earthquake
  • Gene flow
  • Isolation by distance
  • Rapid evolution

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science

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