1,601 research outputs found
The Diverse Applications of Cladistic Analysis of Molecular Evolution, with Special Reference to Nested Clade Analysis
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
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
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
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
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
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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Phylogeography: Retrospect and prospect
Phylogeography has grown explosively in the two decades since the word was coined and the discipline was outlined in 1987. Here I summarize the many achievements and novel perspectives that phylogeography has brought to population genetics, phylogenetic biology and biogeography. I also address future directions for the field. From the introduction of mitochondrial DNA assays in the late 1970s, to the key distinction between gene trees and species phylogenies, to the ongoing era of multi-locus coalescent theory, phylogeographic perspectives have consistently challenged conventional genetic and evolutionary paradigms, and they have forged empirical and conceptual bridges between the formerly separate disciplines of population genetics (microevolutionary analysis) and phylogenetic biology (in macroevolution). © 2008 The Author
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