Evolution of stickleback in 50 years on earthquake-uplifted islands

Emily A. Lescak, Susan L. Bassham, Julian Catchen, Ofer Gelmond, Mary L. Sherbick, Frank A. Van Hippel, William A. Cresko

Research output: Contribution to journalArticle

Abstract

How rapidly can animal populations in the wild evolve when faced with sudden environmental shifts? Uplift during the 1964 Great Alaska Earthquake abruptly created freshwater ponds on multiple islands in Prince William Sound and the Gulf of Alaska. In the short time since the earthquake, the phenotypes of resident freshwater threespine stickleback fish on at least three of these islands have changed dramatically from their oceanic ancestors. To test the hypothesis that these freshwater populations were derived from oceanic ancestors only 50 y ago, we generated over 130,000 singlenucleotide polymorphism genotypes from more than 1,000 individuals using restriction site-associated DNA sequencing (RAD-seq). Population genomic analyses of these data support the hypothesis of recent and repeated, independent colonization of freshwater habitats by oceanic ancestors. We find evidence of recurrent gene flow between oceanic and freshwater ecotypes where they co-occur. Our data implicate natural selection in phenotypic diversification and support the hypothesis that the metapopulation organization of this species helps maintain a large pool of genetic variation that can be redeployed rapidly when oceanic stickleback colonize freshwater environments. We find that the freshwater populations, despite population genetic analyses clearly supporting their young age, have diverged phenotypically from oceanic ancestors to nearly the same extent as populations that were likely founded thousands of years ago. Our results support the intriguing hypothesis that most stickleback evolution in fresh water occurs within the first few decades after invasion of a novel environment.

Original languageEnglish (US)
Pages (from-to)E7204-E7212
JournalProceedings of the National Academy of Sciences of the United States of America
Volume112
Issue number52
DOIs
StatePublished - Dec 29 2015

Keywords

  • Adaptation
  • Contemporary evolution
  • Ecological divergence
  • Metapopulation
  • Population genomics

ASJC Scopus subject areas

  • General

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