Rapid spread of invasive genes into a threatened native species

Benjamin M. Fitzpatrick, Jarrett R. Johnson, D. Kevin Kump, Jeramiah J. Smith, S. Randal Voss, H. Bradley Shaffer

Research output: Contribution to journalArticlepeer-review

157 Scopus citations


When introduced or cultivated plants or animals hybridize with their native relatives, the spread of invasive genes into native populations might have biological, aesthetic, and legal implications. Models suggest that the rate of displacement of native by invasive alleles can be rapid and inevitable if they are favored by natural selection. We document the spread of a few introduced genes 90 km into a threatened native species (the California Tiger Salamander) in 60 years. Meanwhile, a majority of genetic markers (65 of 68) show little evidence of spread beyond the region where introductions occurred. Using computer simulations, we found that such a pattern is unlikely to emerge by chance among selectively neutral markers. Therefore, our results imply that natural selection has favored both the movement and fixation of these exceptional invasive alleles. The legal status of introgressed populations (native populations that are slightly genetically modified) is unresolved by the US Endangered Species Act. Our results illustrate that genetic and ecological factors need to be carefully weighed when considering different criteria for protection, because different rules could result in dramatically different geographic areas and numbers of individuals being protected.

Original languageEnglish
Pages (from-to)3606-3610
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number8
StatePublished - Feb 23 2010


  • Ambystoma
  • California Tiger Salamander
  • Conservation
  • Genetics
  • Hybridization

ASJC Scopus subject areas

  • General


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