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McClure-Baker S.A.,Oklahoma State University | McClure-Baker S.A.,Dexter National Fish Hatchery and Technology Center | Echelle A.A.,Oklahoma State University | van den Bussche R.A.,Oklahoma State University | And 3 more authors.
Transactions of the American Fisheries Society | Year: 2010

Collections of 231 catfish from 34 localities were surveyed for mtDNA (399 base pairs of cytochrome b) and morphological evidence of headwater catfish Ictalurus lupus in areas of historical occurrence in Texas and New Mexico. The species is of concern for conservation managers, primarily because of the potential for population losses from competition and hybridization with channel catfish I. punctatus. For cytochrome b, there were two deeply divergent (4.8-6.1%) groups, a channel catfish clade of 14 haplotypes (0.8% to 1.3% divergence) and a headwater catfish clade of two haplotypes (1.0% divergence), associated with morphotypes of channel catfish and headwater catfish, respectively. Morphotypes were based on field identification and a canonical discriminant function utilizing external morphology. All specimens from the Nueces River and the main-stem Rio Grande and the Pecos River conformed to morphological and mtDNA expectations for channel catfish. Apparently pure populations of headwater catfish were found only in two relatively isolated situations (Rocky Arroyo, New Mexico, and San Solomon Spring, Texas). Additional genetic evidence of headwater catfish was restricted to four populations in streams that are direct tributaries of either the Pecos River or the Rio Grande. Two of these populations (Independence Creek and Dolan Creek-Devils River) were morphologically distinct from, but shifted toward, the morphotype of channel catfish. A third population (Pinto Creek) was morphologically indistinguishable from channel catfish, and individuals from the fourth population (Delaware River) had morphotypes consistent with both species. The Pinto Creek, Independence Creek, and Delaware River populations exhibited mtDNA haplotypes from both species, whereas the Dolan Creek-Devils River population was fixed for a haplotype from the headwater catfish clade. A survey of early collection records tentatively suggests that hybridization between headwater catfish and channel catfish might be a result of relatively recent introduction of the latter to the Rio Grande basin. © by the American Fisheries Society 2010.

Echelle A.A.,Oklahoma State University | De Lourdes Lozano Vilano M.,AP Postal 425 | Baker S.,Dexter National Fish Hatchery and Technology Center | Baker S.,U.S. Fish and Wildlife Service | And 4 more authors.
Copeia | Year: 2013

Variation in mtDNA (cytb sequences) and six microsatellite loci was used to assess the conservation genetics and taxonomy of a group of populations of Gambusia in tributaries of the Rio Grande in Texas (USA) and Coahuila (Mexico): G. clarkhubbsi in San Felipe Creek, Texas, and G. krumholzi. The latter has been considered endemic to the Río de Nava of the Río La Compuerta system, Coahuila, but we found it more widely distributed, both in the Río La Compuerta and outside that system, with a population in the Río San Diego, another Rio Grande in Coahuila. Our results, including reassessment of the morphological characters used to describe G. clarkhubbsi, suggest that G. clarkhubbsi is a junior synonym of G. krumholzi. The San Felipe Creek population (G. cf. clarkhubbsi) had only the common cytb haplotype of G. krumholzi, and none of the microsatellite loci was diagnostic of the two. However, the San Felipe Creek population is the most divergent of the known populations of G. krumholzi. Diversity attributable to among-population differences was six-fold greater when the San Felipe Creek population was included in the AMOVA than when it was excluded (38.5% versus 6.5%). A search for evidence of genetic introgression by G. speciosa as a factor in microsatellite divergence found only one F1 hybrid and two first-generation backcross progeny. Based on the genetic structure and restricted distribution of G. krumholzi, the San Felipe Creek population and four populations in Mexico are recommended as management units for future monitoring. © 2013 by the American Society of Ichthyologists and Herpetologists.

Martin R.M.,Dexter National Fish Hatchery and Technology Center | Keeler-Foster C.L.,Dexter National Fish Hatchery and Technology Center | Boykin K.G.,New Mexico State University | Zegers G.,University of Maine at Machias | Wilson W.D.,Dexter National Fish Hatchery and Technology Center
Conservation Genetics Resources | Year: 2012

Wyoming toad (Bufo baxteri) is an endangered amphibian native to the Laramie Basin, Wyoming, USA. A captive breeding program propagates B. baxteri, and the monitoring of genetic diversity in captive stock can assist in guiding restoration and recovery efforts. We developed eight species-specific polymorphic loci from an enriched microsatellite library. For 281 samples, B. baxteri exhibited 2-11 alleles per locus, and observed and expected heterozygosities per locus ranged from 0.411 to 0.943 and from 0.400 to 0.691, respectively. Four loci deviated significantly from Hardy-Weinberg equilibrium. The eight microsatellite markers may be useful for conservation, population, and quantitative genetics for B. baxteri and closely related species. © 2011 Springer Science+Business Media B.V.(outside the USA).

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