Escape to Alcatraz: evolutionary history of slender salamanders (Batrachoseps) on the islands of San Francisco Bay

<p>Abstract</p> <p>Background</p> <p>Island populations are excellent model systems for studies of phenotypic, ecological and molecular evolution. In this study, molecular markers of mitochondrial and nuclear derivation were used to investigate the evolution, structure and origin of populations of the California slender salamander (<it>Batrachoseps attenuatus</it>) inhabiting the six major islands of San Francisco Bay, formed following the rising of sea level around 9,000 years ago.</p> <p>Results</p> <p>There was a high degree of congruence in the results of analyses of nucleotide and allozyme data, both of which strongly support the hypothesis that, for the majority of the islands, salamanders are descended from hilltop populations that became isolated with the formation of the Bay ca. 9,000 years ago. There are two exceptions (Alcatraz and Yerba Buena) where the evidence suggests that salamander populations are wholly or in part, the result of anthropogenic introductions.</p> <p>Comparison of the molecular data and the interpretations drawn therefrom with an earlier morphological study of many of the same salamander populations show some of the same evolutionary trends.</p> <p>Conclusion</p> <p>In spite of marked differences between the evolutionary rates of the two kinds of molecular markers, both indicate distinctive and similar patterns of population structure for <it>B. attenuatus </it>in the San Francisco Bay Area and its islands. With the two noted exceptions, it is clear that most island populations were established prior to the 9,000 years since the formation of the Bay. Results of coalescence-based analyses suggest that for most island populations the mtDNA lineages from which they were derived date from the Pleistocene.</p> <p>It can be said that, based on observed values of genetic diversity, the last 9,000 years of evolution on these islands have been characterized by relative stability, with the occasional extinction of some haplotypes or alleles that were formerly shared between island and mainland populations but overall maintaining high levels of variation (with the exception of Alcatraz). In contrast, there is some evidence for rapid morphological changes between populations in some islands and their closest mainland counterparts. This pattern of rapid morphological divergence (e. g., resulting from founder effects) is similar to that observed in other studies about recent colonization of island habitats.</p

ON THE GEOGRAPHIC DISTRIBUTION OF NEMOGNATHA PLAUMANNI BORCHMANN, 1942 (COLEOPTERA: MELOIDAE): NEW RECORDS FROM VENEZUELA, WITH A 4500 KM RANGE EXTENSION

Nemognatha plaumanni Borchmann, 1942 (Coleoptera: Meloidae: Nemognathinae) was described from a single specimen found in Brazil, and since its description no additional information has been published on the species. During a field survey in Venezuela, we found one individual morphologically assignable to the species. In this note, we report and discuss this finding, which, together with the revision of the entomological collections of the Magyar Természettudományi Múzeum (Hungarian Natural History Museum, HNHM, Budapest, Hungary), the Natural History Museum (NHM, London, UK), and the Museo del Instituto de Zoología Agrícola (MIZA, Maracay, Venezuela), has led us to acknowledge the presence of the species in Venezuela, therefore extending the known distribution range of the species by more than 4500 km. We discuss the possibility that N. plaumanni might in fact correspond to a complex of cryptic species distributed over this vast range, an hypothesis that has to be tested with further field- and lab-work

Complementing the Pleistocene biogeography of European amphibians: Testimony from a southern Atlantic species

To reconstruct the historical biogeography of Hyla molleri, a tree frog endemic to the Eurosiberian and Mediterranean bioclimatic zones in the Iberian Peninsula. Location: Iberian Peninsul

An extended mtDNA phylogeography for the alpine newt illuminates the provenance of introduced populations

Many herpetofauna species have been introduced outside of their native range. MtDNA barcoding is regularly used to determine the provenance of such populations. The alpine newt has been introduced across the Netherlands, the United Kingdom and Ireland. However, geographical mtDNA structure across the natural range of the alpine newt is still incompletely understood and certain regions are severely undersampled. We collect mtDNA sequence data of over seven hundred individuals, from both the native and the introduced range. The main new insights from our extended mtDNA phylogeography are that 1) haplotypes from Spain do not form a reciprocally monophyletic clade, but are nested inside the mtDNA clade that covers western and eastern Europe; and 2) haplotypes from the northwest Balkans form a monophyletic clade together with those from the Southern Carpathians and Apuseni Mountains. We also home in on the regions where the distinct mtDNA clades meet in nature. We show that four out of the seven distinct mtDNA clades that comprise the alpine newt are implicated in the introductions in the Netherlands, United Kingdom and Ireland. In several introduced localities, two distinct mtDNA clades co-occur. As these mtDNA clades presumably represent cryptic species, we urge that the extent of genetic admixture between them is assessed from genome-wide nuclear DNA markers. We mobilized a large number of citizen scientists in this project to support the collection of DNA samples by skin swabbing and underscore the effectiveness of this sampling technique for mtDNA barcoding

La conservación de los anfibios de Madrid fundamentos corológicos y moleculares

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología evolutiva y Biodiversidad. Fecha de lectura: 26-03-200

Data from: Hybridization during altitudinal range shifts: nuclear introgression leads to extensive cyto-nuclear discordance in the fire salamander

Ecological models predict that, in the face of climate change, taxa occupying steep altitudinal gradients will shift their distributions, leading to the contraction or extinction of the high-elevation (cold-adapted) taxa. However, hybridization between eco-morphologically divergent taxa commonly occurs in nature and may lead to alternative evolutionary outcomes, such as genetic merger or gene flow at specific genes. We evaluate this hypothesis by studying patterns of divergence and gene flow across three replicate contact zones between high- and low-elevation ecomorphs of the fire salamander (Salamandra salamandra) that have experienced altitudinal range shifts over the current postglacial period. Strong population structure with high genetic divergence in mitochondrial DNA suggests that vicariant evolution has occurred over several glacial-interglacial cycles, and that it has led to cryptic differentiation within ecomorphs. In current parapatric boundaries we do not find evidence for local extinction and replacement upon postglacial expansion. Instead parapatric taxa recurrently show discordance between mitochondrial and nuclear markers, suggesting nuclear mediated gene flow across contact zones. Isolation with migration models support this hypothesis by showing significant gene flow across all five parapatric boundaries. Together, our results suggest that, while some genomic regions, such as the mitochondria, may follow morphologic species traits and retreat to isolated mountain tops, other genomic regions, such as nuclear markers, may flow across parapatric boundaries, sometimes leading to a complete genetic merger. We show that despite high ecologic and morphologic divergence over prolonged periods of time, hybridization allows for evolutionary outcomes alternative to extinction and replacement of taxa in response to climate change

Provenance of Ichthyosaura alpestris (Caudata: Salamandridae) introductions to France and New Zealand assessed by mitochondrial DNA analysis

The last century has seen an unparalleled movement of species around the planet as a direct result of human activity, which has been a major contributor to the biodiversity crisis. Amphibians represent a particularly vulnerable group, exacerbated by the devastating effects of chytrid fungi. We report the malicious translocation and establishment of the alpine newt (Ichthyosaura alpestris) to its virtual antipode in North Island of New Zealand. We use network analysis of mitochondrial DNA haplotypes to identify the original source population as I. a. apuana from Tuscany, Italy. Additionally, a population in southern France, presumed to be introduced, is identified as I. a. alpestris from western Europe. However, the presence of two differentiated haplotypes suggests a mixed origin. This type of analysis is made possible by the recent availability of a phylogenetic analysis of the species throughout its natural range. We discuss the particulars of both introductions