1,601 research outputs found

    The Diverse Applications of Cladistic Analysis of Molecular Evolution, with Special Reference to Nested Clade Analysis

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    The genetic variation found in small regions of the genomes of many species can be arranged into haplotype trees that reflect the evolutionary genealogy of the DNA lineages found in that region and the accumulation of mutations on those lineages. This review demonstrates some of the many ways in which clades (branches) of haplotype trees have been applied in recent years, including the study of genotype/phenotype associations at candidate loci and in genome-wide association studies, the phylogeographic history of species, human evolution, the conservation of endangered species, and the identification of species

    Speciation and phylogeography: coalescent-based models applied to the Cape plant genus Pauridia

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    The Cape (CFR) is an exceptional centre plant This diversity is concentrated in a profusion geographically restricted endemic species within a The CFR is a rich and dynamic for the molecular study of speciation, but until recently studies have focused on factors influencing diversification of whole lineages, than on details the speciation process within and between species pairs

    Speciation and phylogeography: coalescent-based models applied to the Cape plant genus Pauridia

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    The Cape (CFR) is an exceptional centre plant This diversity is concentrated in a profusion geographically restricted endemic species within a The CFR is a rich and dynamic for the molecular study of speciation, but until recently studies have focused on factors influencing diversification of whole lineages, than on details the speciation process within and between species pairs

    Evolutionary and demographic correlates of Pleistocene coastline changes in the Sicilian wall lizard Podarcis wagleriana

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    Aim Emergence of coastal lowlands during Pleistocene ice ages might have provided conditions for glacial expansions (demographic and spatial), rather than contraction, of coastal populations of temperate species. Here, we tested these predictions in the insular endemic Sicilian wall lizard Podarcis wagleriana. Location Sicily and neighbouring islands. Methods We sampled 179 individuals from 45 localities across the whole range of P. wagleriana. We investigated demographic and spatial variations through time using Bayesian coalescent models (Bayesian phylogeographic reconstruction, Extended Bayesian Skyline plots, Isolation‐with‐migration models) based on multilocus DNA sequence data. We used species distribution modelling to reconstruct present and past habitat suitability. Results We found two main lineages distributed in the east and west portions of the current species range and a third lineage restricted to a small area in the north of Sicily. Multiple lines of evidence from palaeogeographic (shorelines), palaeoclimatic (species distribution models), and multilocus genetic data (demographic and spatial Bayesian reconstructions) indicate that these lineages originated in distinct refugia, located in the north‐western and south‐eastern coastal lowlands, during Middle Pleistocene interglacial phases, and came into secondary contact following demographic and spatial expansions during the last glacial phase. Main conclusions This scenario of interglacial contraction and glacial expansion is in sharp contrast with patterns commonly observed in temperate species on the continent but parallels recent findings on other Mediterranean island endemics. Such a reverse expansion–contraction (EC) dynamic has been likely associated with glacial increases of climatically suitable coastal lowlands, suggesting this might be a general pattern in Mediterranean island species and also in other coastal regions strongly affected by glacial marine regressions during glacial episodes. This study provides explicit predictions and some methodological recommendations for testing the reverse EC model in other region and taxa

    Signals of demographic expansion in Drosophila virilis

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    BACKGROUND: The pattern of genetic variation within and among populations of a species is strongly affected by its phylogeographic history. Analyses based on putatively neutral markers provide data from which past events, such as population expansions and colonizations, can be inferred. Drosophila virilis is a cosmopolitan species belonging to the virilis group, where divergence times between different phylads go back to the early Miocene. We analysed mitochondrial DNA sequence variation among 35 Drosophila virilis strains covering the species' range in order to detect demographic events that could be used to understand the present characteristics of the species, as well as its differences from other members of the group. RESULTS: Drosophila virilis showed very low nucleotide diversity with haplotypes distributed in a star-like network, consistent with a recent world-wide exponential expansion possibly associated either with domestication or post-glacial colonization. All analyses point towards a rapid population expansion. Coalescence models support this interpretation. The central haplotype in the network, which could be interpreted as ancestral, is widely distributed and gives no information about the geographical origin of the population expansion. The species showed no geographic structure in the distribution of mitochondrial haplotypes, in contrast to results of a recent microsatellite-based analysis. CONCLUSION: The lack of geographic structure and the star-like topology depicted by the D. virilis haplotypes indicate a pattern of global demographic expansion, probably related to human movements, although this interpretation cannot be distinguished from a selective sweep in the mitochondrial DNA until nuclear sequence data become available. The particular behavioural traits of this species, including weak species-discrimination and intraspecific mate choice exercised by the females, can be understood from this perspective

    Reconstructing South African Afromontane forest history with bryophyte phylogeography

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    Includes bibliographical references (leaves 46-54).Forests occur as fragmented patches throughout Africa, however the basis for the disjunction of afromontane forests remains uncertain. The genetic structure of organisms should reflect their hi story, and in turn the history of their environment. Thus a phylogeographical study of forest-faithful mosses could provide insight into the fragmentation of forests. In this study, patterns of genetic variation in four forest-faithful mosses (Leptodon smithii, Pyrrhobryum spiniforme, Aerobryopsis capensis and Neckera valentiniana) were investigated
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