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Lepidomeda vittata (the Little Colorado River spinedace) is a cyprinid fish native to the Little Colorado River in Arizona. Mitochondrial DNA and allozymes were used to determine patterns of genetic variation in remaining populations of L. vittata. The pattern of variation observed indicated that genetic diversity was low, but population structure was high because of partitioning of genotypes among samples. Similarity of genotypes suggest current populations are relics from a single, large population that was one continuously distributed throughout the LCR drainage. Patterns of variation were consistent with decreases in population size; however, because of low levels of variation, it was impossible to determine...
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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...
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The extent and impact of introgressive hybridization was examined in the Gila robusta complex of cyprinid fishes using mitochondrial DNA (mtDNA) sequence variation. Lower Colorado River basin populations of G. robusta, G. elegans, and G. cypha exhibited distinct mtDNAs, with only limited introgression of G. elegans into G. cypha. The impact of hybridization was significant in upper Colorado River basin populations; most upper basin fishes sampled exhibited only G. cypha mtDNA haplotypes, with some individuals exhibiting mtDNA from G. elegans. The complete absence of G. robusta mtDNA, even in populations of morphologically pure G. robusta, indicates extensive introgression that predates human influence. Analysis...
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Conservation biologists rely heavily on taxonomy to set the scope for biological monitoring and recovery planning of rare or threatened species. Yet, taxonomic boundaries are seldom evaluated as falsifiable hypotheses that can be statistically tested. Here, we examine species boundaries in leatherside chub (Teleostei, Cyprinidae), an imperiled desert fish native to the Bonneville Basin and upper Snake River drainages of western North America. Recent molecular data hint that this fish could be composed of two distinct taxa that are geographically separated into northern and southern species. To formally test this hypothesis, we evaluated leatherside chub using several different categories of species concepts, including...
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