Bradford D. Hollingsworth

Montane refugia predict population genetic structure in the Large-blotched Ensatina salamander

Understanding the biotic consequences of Pleistocene range shifts and fragmentation remains a fundamental goal in historical biogeography and evolutionary biology. Here, we combine species distribution models (SDM) from the present and two late Quaternary time periods with multilocus genetic data (mitochondrial DNA and microsatellites) to evaluate the effect of climate‐induced habitat shifts on population genetic structure in the Large‐blotched Ensatina (Ensatina eschscholtzii klauberi), a plethodontid salamander endemic to middle and high‐elevation conifer forest in the Transverse and Peninsular Ranges of southern California and northern Baja California. A composite SDM representing the range through time predicts two disjunct refugia, one in southern California encompassing the core of the species range and the other in the Sierra San Pedro Mártir of northern Baja California at the southern limit of the species range. Based on our spatial model, we would expect a pattern of high connectivity among populations within the northern refugium and, conversely, a pattern of isolation due to long‐term persistence of the Sierra San Pedro Mártir population. Our genetic results are consistent with these predictions based on the hypothetical refugia in that (i) historical measures of population connectivity among stable areas are correlated with gene flow estimates; and (ii) there is strong geographical structure between separate refugia. These results provide evidence for the role of recent climatic change in shaping patterns of population persistence and connectivity within the Transverse and Peninsular Ranges, an evolutionary hotspot.

A coastal population of Large-blotched Ensatina Ensatina klauberi (Caudata: Plethodontidae) in Baja California, México

We found a new population of Ensatina klauberi in San Quintin volcanic field, Baja California. It represents the first coastal population of this species. This record extends the species range ca. 71 km southwest of the southernmost record of E. klauberi in the Sierra San Pedro Martir and represents the first population discovered outside of coniferous and pine-oak woodlands.

Distribution and conservation of lizards in the Vizcaíno Biosphere Reserve, Baja California Sur, México

Lizard distribution is described for the Vizcaino Biosphere Reserve in the northern extreme of Baja California Sur, in central Baja California. The 20 species found include 74% of all the Baja California Sur lizards, excluding insular endemics. Five species are widely distributed throughout the Reserve. Four species are restricted to sandy soils (coarse and dunes) and open spaces. Seven species are restricted to rocky areas in the Sierras. Two species are included in the CITES list and 11 in the Official Mexican Norm (NOM 059-94) in some conservation category. This Reserve contains livestock (cows and goats), whose increasing numbers and grazing areas are often unrestricted. This disturbance is a potential threat for some species, especially those with restricted distributions in the eastern sierras where there are large numbers of goats.

Occurrence of Batrachochytrium dendrobatidis in anurans of the Mediterranean region of Baja California, México

Chytridiomycosis is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) and is regarded as one of the most significant threats to global amphibian populations. In México, Bd was first reported in 2003 and has now been documented in 13 states. We visited 33 localities and swabbed 199 wild-caught anurans from 7 species (5 native, 2 exotic) across the Mediterranean region of the state of Baja California. Using quantitative PCR, Bd was detected in 94 individuals (47.2% of samples) at 25 of the 33 survey localities for 5 native and 1 exotic frog species. The exotic Xenopus laevis was the only species that tested completely negative for Bd. We found that remoteness, distance to agricultural land, and elevation were the best positive predictors of Bd presence. These are the first Bd-positive results for the state of Baja California, and its presence should be regarded as an additional conservation threat to the regions native frog species.

The Phylogenetic Position of the Little Mexican Toad, Anaxyrus kelloggi, Using Molecular Data

Abstract We tested the phylogenetic position of Anaxyrus kelloggi, a distinctive toad species from coastal northwestern Mexico, using a ~2.4-kilobase fragment of mitochondrial ribosomal RNA gene regions and maximum likelihood and Bayesian analyses. The two approaches recovered nearly identical phylogenetic topologies, which provide strong support for placement of A. kellogi in the debilis group, as sister taxon to the clade formed by A. debilis and A. retiformis. Species relationships within the debilis group are also well supported and concordant with aspects of earlier, morphology-based hypotheses. Resumen Evaluamos la posición filogenética de Anaxurus kelloggi, una especie de sapo distintivo de la costa noroeste de México utilizando ~2.4 kb de un fragmento de regiones del ARN ribosomal en el gen mitocondrial y análisis de máxima verosimilitud y bayesianos. Los dos criterios recobraron topologías filogenéticas casi idénticas, la cual provee alto soporte de la afiliación de A. kelloggi dentro del grupo debilis, como hermano al clado conformado por A. debilis y A. retiformis. Las relaciones de especies dentro del grupo debilis tienen alto apoyo y concuerdan con aspectos de las hipótesis previas basadas en morfología.