Genetic rescue and inbreeding depression in Mexican wolves

Richard J. Fredrickson, Peter Siminski, Melissa Woolf, Philip W. Hedrick

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


Although inbreeding can reduce individual fitness and contribute to population extinction, gene flow between inbred but unrelated populations may overcome these effects. Among extant Mexican wolves (Canis lupus baileyi), inbreeding had reduced genetic diversity and potentially lowered fitness, and as a result, three unrelated captive wolf lineages were merged beginning in 1995. We examined the effect of inbreeding and the merging of the founding lineages on three fitness traits in the captive population and on litter size in the reintroduced population. We found little evidence of inbreeding depression among captive wolves of the founding lineages, but large fitness increases, genetic rescue, for all traits examined among F1 offspring of the founding lineages. In addition, we observed strong inbreeding depression among wolves descended from F1 wolves. These results suggest a high load of deleterious alleles in the McBride lineage, the largest of the founding lineages. In the wild, reintroduced population, there were large fitness differences between McBride wolves and wolves with ancestry from two or more lineages, again indicating a genetic rescue. The low litter and pack sizes observed in the wild population are consistent with this genetic load, but it appears that there is still potential to establish vigorous wild populations.

Original languageEnglish (US)
Pages (from-to)2365-2371
Number of pages7
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1623
StatePublished - Sep 22 2007


  • Conservation genetics
  • Genetic rescue
  • Inbreeding
  • Inbreeding depression
  • Wolves

ASJC Scopus subject areas

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


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