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Geographic distributions of most temperate marine fishes are affected by postglacial recolonisation events, which have left complex genetic imprints on populations of marine species. This study investigated population structure and demographic history of European sprat (Sprattus sprattus L.) by combining inference from both mtDNA and microsatellite genetic markers throughout the species' distribution. We compared effects from genetic drift and mutation for both genetic markers in shaping genetic differentiation across four transition zones. Microsatellite markers revealed significant isolation by distance and a complex population structure across the species′ distribution (overall θST=0.038, P<0.01). Across transition zones markers indicated larger effects of genetic drift over mutations in the northern distribution of sprat contrasting a stronger relative impact of mutation in the species' southern distribution in the Mediterranean region. These results were interpreted to reflect more recent divergence times between northern populations in accordance with previous findings. This study demonstrates the usefulness of comparing inference from different markers and estimators of divergence for phylogeographic and population genetic studies in species with weak genetic structure, as is the case in many marine species. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibetan Plateau is one of the most extensive habitats for alpine plants in the world. Therefore, the patterns of genetic variation in populations on the Plateau can reveal the detailed demographic history of alpine plants. We analysed the geographical structure of chloroplast matK sequence variation in Potentilla fruticosa L. (Rosaceae), a shrub currently found across the entire Plateau. We obtained sequence data from 508 individuals from 23 populations at sites ranging from the high-altitude interior to the relatively low-altitude northeastern Plateau. In the interior region, genetic diversity was high and included ancestral haplotypes. In contrast, northeastern populations were characterized by relatively low genetic diversity and recently derived haplotypes. The estimated expansion time in the interior population was 17 times that in the northeastern population. These data suggest that P. fruticosa expanded its range on the Plateau during periods of climatic cooling and contracted to the interior region during warmer periods. Thus, the interior region acted as a refugium and greatly contributed to the diversification of P. fruticosa. [ABSTRACT FROM AUTHOR]

We use phylogenetic techniques to investigate the postglacial re-population of Europe by the common frog and, in particular, the colonization of Ireland. Three main hypotheses have been proposed for the re-establishment of the Irish fauna after the last ice age: arrival across a late-glacial land bridge from Britain; expansion from a glacial refuge in the south of Ireland and, for some species, re-introduction by humans from Iberia. We examined the phylogeographic structure of 52 populations of the common frog (Rana temporaria) throughout Europe using 476-bp mitochondrial cytochrome b gene sequences. Our data replicate earlier studies in showing substantial sequence divergence (3%) between Eastern and Western European common frog haplotypes. However, we uncover a new evidence that these haplotypes co-exist in Spain, Switzerland and France, and infer an expansion of the eastern clade along the Mediterranean coastal corridor. All the British samples fall within the Western European clade, but the Irish data imply a different history. Genetically distinct haplotypes occur in populations from the south-west of Ireland. This local genetic differentiation may be a consequence of a local glacial refuge, possibly combined with natural colonization or introduction from Western Europe.Heredity (2009) 102, 490–496; doi:10.1038/hdy.2008.133; published online 21 January 2009 [ABSTRACT FROM AUTHOR]

The vicuña (Vicugna vicugna; Miller, 1924) is a conservation success story, having recovered from near extinction in the 1960s to current population levels estimated at 275 000. However, lack of information about its demographic history and genetic diversity has limited both our understanding of its recovery and the development of science-based conservation measures. To examine the evolution and recent demographic history of the vicuña across its current range and to assess its genetic variation and population structure, we sequenced mitochondrial DNA from the control region (CR) for 261 individuals from 29 populations across Peru, Chile and Argentina. Our results suggest that populations currently designated as Vicugna vicugna vicugna and Vicugna vicugna mensalis comprise separate mitochondrial lineages. The current population distribution appears to be the result of a recent demographic expansion associated with the last major glacial event of the Pleistocene in the northern (18 to 22°S) dry Andes 14–12 000 years ago and the establishment of an extremely arid belt known as the ‘Dry Diagonal’ to 29°S. Within the Dry Diagonal, small populations of V. v. vicugna appear to have survived showing the genetic signature of demographic isolation, whereas to the north V. v. mensalis populations underwent a rapid demographic expansion before recent anthropogenic impacts.Heredity (2007) 99, 70–80; doi:10.1038/sj.hdy.6800966; published online 11 April 2007 [ABSTRACT FROM AUTHOR]

The author reflects on the study of ancient post-glacial colonization routes. He states that the significance of post-glacial routes arise when climatic changes affect genetic diversity. He cites that the last region to become free of ice and more recently colonized was Northern Europe. He also highlights the impact of global warming and divergent colonization lineages in genetic variation.