John F. Switzer | USGS Science

USGS2009

Genetic structure in the Anaxyrus boreas species group (anura, Bufonidae): an evaluation of the Southern Rocky Mountain population

The Anaxyrus boreas species group is comprised of four species endemic to the western United States: A. boreas, A. canorus, A. exsul, and A. nelsoni. Disjunct populations of the widespread western toad Anaxyrus boreas from Colorado and southern Wyoming, the southern rocky mountain population (SRMP), were previously candidates for listing under the United States Endangered Species Act (ESA) as a distinct population segment (DPS), but were removed due to a lack of significant genetic differentiation in preliminary studies. The purpose of this study was to conduct phylogeographic and population genetic analyses of A. boreas and three related species using mitochondrial DNA sequence data and nuclear microsatellite genotype data. The study is specifically focused on testing the evolutionary significance of the SRMP.

Final Report↗

USGS2006

Comprehensive genetic analyses reveal evolutionary distinction of a mouse ( Zapus hudsonius preblei ) proposed for delisting from the US Endangered Species Act

Zapus hudsonius preblei, listed as threatened under the US Endangered Species Act (ESA), is one of 12 recognized subspecies of meadow jumping mice found in North America. Recent morphometric and phylogenetic comparisons among Z. h. preblei and neighbouring conspecifics questioned the taxonomic status of selected subspecies, resulting in a proposal to delist the Z. h. preblei from the ESA. We present additional analyses of the phylogeographic structure within Z. hudsonius that calls into question previously published data (and conclusions) and confirms the original taxonomic designations. A survey of 21 microsatellite DNA loci and 1380 base pairs from two mitochondrial DNA (mtDNA) regions (control region and cytochrome b) revealed that each Z. hudsonius subspecies is genetically distinct. These data do not support the null hypothesis of a homogeneous gene pool among the five subspecies found within the southwestern portion of the species' range. The magnitude of the observed differentiation was considerable and supported by significant findings for nearly every statistical comparison made, regardless of the genome or the taxa under consideration. Structuring of nuclear multilocus genotypes and subspecies-specific mtDNA haplotypes corresponded directly with the disjunct distributions of the subspecies investigated. Given the level of correspondence between the observed genetic population structure and previously proposed taxonomic classification of subspecies (based on the geographic separation and surveys of morphological variation), we conclude that the nominal subspecies surveyed in this study do not warrant synonymy, as has been proposed for Z. h. preblei, Z. h. campestris, and Z. h. intermedius. ?? 2006 The Authors.

Molecular Ecology↗