The endangered Sonoran topminnow: Examination of species and ESUs using three mtDNA genes

P. W. Hedrick, R. N. Lee, C. R. Hurt

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


There has been controversy over the species status of Sonoran topminnows and debate about the presence of ESUs in the Gila topminnow. From examination of sequence variation at 2626 base pairs over three mtDNA genes, we found a 29 (1.1%) nucleotide genetic difference between Gila and Yaqui topminnows. This provides strong support that these two taxa are separate species, Poeciliopsis occidentalis (Gila topminnow) and P. sonoriensis (Yaqui topminnow) and have been separated for approximately one million years. All the Gila topminnows within Arizona have the same sequence for the three mtDNA genes, that is, there is not reciprocal monophyly for mtDNA sequence data for the two previously designated ESUs. However, evidence of the unique habitat for Monkey Spring, its long-term isolation from other Gila topminnow habitats, and the presence of unique fish and invertebrate taxa in Monkey Spring support the designation of the Monkey Spring topminnows as an ESU. Finally, theoretical considerations using molecular data and estimates of heterozygosity and genetic distance for nuclear genes between populations of the Gila topminnow show that the lack of mtDNA variation is not inconsistent with the level and pattern of nuclear genetic variation observed.

Original languageEnglish (US)
Pages (from-to)483-492
Number of pages10
JournalConservation Genetics
Issue number4
StatePublished - Aug 2006


  • ESU
  • Effective population size
  • Genetic distance
  • Poeciliopsis
  • mtDNA

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics


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