title: Origin of Gila seminuda (Teleostei: Cyprinidae) through introgressive hybridization: implications for evolution and conservation.
abstract: Morphological and genetic characters from cyprinid fishes of the genus Gila were examined to assess a hypothesized hybrid origin of Gila seminuda from the Virgin River, Arizona-Nevada-Utah. The presumed parents, Gila robusta robusta and Gila elegans, are clearly differentiated from one another based on morphology, allozymes, and mtDNA haplotypes. G. seminuda is morphologically intermediate and polymorphic at allozyme loci diagnostic for the parental species. Restriction endonuclease analysis of mtDNA showed G. seminuda nearly identical to G. elegans. These results support an origin of the bisexual taxon G. seminuda through introgressive hybridization. The Gila population in the Moapa River, Nevada, also appears to be of hybrid origin and is considered a distinctive population of G. seminuda. Inter-specific hybridization is potentially an important mode of evolution among western North American fishes, and valid species of hybrid origin may exist in other groups as well. Consideration of this mode of evolution argues for the need to conserve entire species complexes.
authors.affiliation: Department of Zoology, Arizona State University, Tempe 85287-1501.
authors.forename: B D
authors.initials: BD
authors.lastname: DeMarais
authors.forename: T E
authors.initials: TE
authors.lastname: Dowling
authors.forename: M E
authors.initials: ME
authors.lastname: Douglas
authors.forename: W L
authors.initials: WL
authors.lastname: Minckley
authors.forename: P C
authors.initials: PC
authors.lastname: Marsh
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003530:Cyprinidae / Q000145:classification* / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D006824:Hybridization, Genetic; D007527:Isoenzymes / Q000235:genetics; D015183:Restriction Mapping; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial; D007527:Isoenzymes