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Historical Migration (historical + migration)
Selected AbstractsA long-standing Pleistocene refugium in southern Africa and a mosaic of refugia in East Africa: insights from mtDNA and the common eland antelopeJOURNAL OF BIOGEOGRAPHY, Issue 3 2010Eline D. Lorenzen Abstract Aim, Previous genetic studies of African savanna ungulates have indicated Pleistocene refugial areas in East and southern Africa, and recent palynological, palaeovegetation and fossil studies have suggested the presence of a long-standing refugium in the south and a mosaic of refugia in the east. Phylogeographic analysis of the common eland antelope, Taurotragus oryx (Bovidae), was used to assess these hypotheses and the existence of genetic signatures of Pleistocene climate change. Location, The sub-Saharan savanna biome of East and southern Africa. Methods, Mitochondrial DNA control-region fragments (414 bp) from 122 individuals of common eland were analysed to elucidate the phylogeography, genetic diversity, spatial population structuring, historical migration and demographic history of the species. The phylogeographic split among major genetic lineages was dated using Bayesian coalescent-based methods and a calibrated fossil root of 1.6 Ma for the split between the common eland and the giant eland, Taurotragus derbianus. Results, Two major phylogeographic lineages comprising East and southern African localities, respectively, were separated by a net nucleotide distance of 4.7%. A third intermediate lineage comprised only three haplotypes, from Zimbabwe in southern Africa. The estimated mutation rate of 0.097 Myr,1 revealed a more recent common ancestor for the eastern lineage (0.21 Ma; 0.07,0.37) than for the southern lineage (0.35 Ma; 0.10,0.62). Compared with the latter, the eastern lineage showed pronounced geographic structuring, lower overall nucleotide diversity, higher population differentiation, and isolation-by-distance among populations. Main conclusions, The data support the hypothesis of Pleistocene refugia occurring in East and southern Africa. In agreement with palynological, palaeovegetation and fossil studies, our data strongly support the presence of a longer-standing population in the south and a mosaic of Pleistocene refugia in the east, verifying the efficacy of genetic tools in addressing such questions. The more recent origin of the common eland inhabiting East Africa could result from colonization following extinction from the region. Only two other dated African ungulate phylogenies have been published, applying different methods, and the similarity of dates obtained from the three distinct approaches indicates a significant event c. 200 ka, which left a strong genetic signature across a range of ungulate taxa. [source] Incongruent patterns of genetic connectivity among four ophiuroid species with differing coral host specificity on North Atlantic seamountsMARINE ECOLOGY, Issue 2010Walter Cho Abstract Seamounts are considered to play a defining role in the evolution and diversity of marine fauna, acting as ,stepping-stones' for dispersal, regional centers of genetic isolation and speciation, and refugia for deep-sea populations. This study focused on the patterns of dispersal and genetic connectivity of four seamount ophiuroid species (Asteroschema clavigera, Ophiocreas oedipus, Ophioplinthaca abyssalis, and Ophioplinthaca chelys) displaying differing levels of associative (epifaunal) specificity to cold-water coral hosts inhabiting the New England and Corner Rise Seamount chains, and Muir Seamount in the Northwestern Atlantic. Analyses of mt16S and mtCOI revealed evidence for recent population expansion and high gene flow for all four species. However, species-specific genetic differentiation was significant based on seamount region and depth. Significant differences were found among regional seamount groups for A. clavigera, within seamount regions and seamounts for O. chelys, among 250-m depth intervals for A. clavigera, among 100-m depth intervals for O. oedipus, and there were indications of isolation by distance for A. clavigera and O. oedipus. In addition, A. clavigera and O. oedipus, broadcast spawners with high fidelity to specific coral hosts, displayed predominantly westward historical migration, whereas the ophioplinthacids, with lower host-specificity, displayed predominantly eastward migration. No congruent patterns of historical migration were evident among species and seamounts, yet these patterns can be correlated with species-specific host specificity, specific depth strata, and dispersal strategies. Conservation efforts to protect seamount ecosystems should promote multi-species approaches to genetic connectivity, and consider the impact of the ,dependence' of biodiversity on host fauna in these vulnerable marine ecosystems. [source] Post-last glacial maximum expansion from Iberia to North Africa revealed by fine characterization of mtDNA H haplogroup in TunisiaAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Lotfi Cherni Abstract The first large-scale fine characterization of Tunisian H lineages clarifies that the post-Last glacial maximum expansion originating in Iberia not only led to the resettlement of Europe but also of North Africa. We found that 46% of 81 Tunisian H lineages subscreened for 1,580 bp in mtDNA coding region were affiliated with H1 and H3 subhaplogroups, which are known to have originated in Iberia. Although no signs of local expansion were detected, which would allow a clear dating of their introduction, the younger and less diverse Tunisian H1 and H3 lineages indicate Iberia as the radiating centre. Major contributions from historical migrations to this Iberian genetic imprint in Tunisia were ruled out by the mtDNA gene pool similarity between Berber/Arab/cosmopolitan samples and some "Andalusian" communities, settled by the descendents of the "Moors" who once lived in Iberia for 10 centuries (between 8th and 17th centuries), before being expelled to Tunisia. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||