Habitat islands, genetic diversity, and gene flow in a Patagonian rodent

Abstract

The effects of terrestrial habitat islands on gene flow and genetic diversity in animal populations have been predicted and discussed in theoretical terms, but empirical data are needed to test these predictions and provide an understanding of the relationships of life-history characteristics to genetics of insular species. We studied saxicolous mice (Phyllotis xanthopygus) in Patagonia to explore genetic structure, phylogeography, and gene flow in a species inhabiting natural habitat islands. Phylogeographic analyses based on mtDNA sequences revealed two haplotype clades, which presumably reflect early Pleistocene factors that temporarily separated the mice into two geographically isolated groups. The Río Chubut, which lies within a glacial drainage basin bisecting northern Patagonia, might have affected gene flow in the species. Although we anticipated isolation by distance and founder phenomena associated with habitat islands, in some habitat patches we found evidence of high local genetic diversity. The amount of divergence in the mitochondrial cytochrome b gene (approximately 3.4%) in animals at a single locality could best be explained through a combination of historical factors and metapopulation source-sink theory. Demographic shifts, dispersal, and episodic recolonization are important in the life history and genetic population structure of P. xanthopygus.

Population genetic structure and historical population dynamics of the South American sea lion, Otaria flavescens, in north-central Patagonia

“…If such expansions occurred too recently for mtDNA to accumulate point mutations, low genetic diversity and weak phylogeographical patterns would be observed today, as appears to occur in O. flavescens in north-central Patagonia. Other evidences in favour of habitat contractions and reduced genetic diversity caused by Pleistocene glacial cycles came from studies in different species that inhabits the southern hemisphere, which include several species of plants (Allnutt et al 1999(Allnutt et al , 2003Premoli et al 2002;Muellner et al 2005) and fishes (Zattara and Premoli 2005;Ruzzante et al 2006); the rock shags, Stictocarbo magellanicus, (Siegel-Causey 1997) and the saxicolous mice, Phyllotis xanthopygus (Kim et al 2002). Another member of the Family Otariidae, Arctocephalus pusillus pusillus, also show a population dynamics associated with the dynamics of glaciations, but in a inverse way.…”

Geographic Genetic Contour of a Ground Beetle, Scarites aterrimus (Coleoptera: Carabidae) on the Basis of Mitochondrial DNA Sequence

“…A detailed rationale of this method is described in the original study of Holsinger and Mason-Gamer (1996) and other reports, which utilized this method (Kim et al, 1998). Unlike other variance analyses, this approach generated the hierarchical relationships of the groups without specifying the hierarchical structure of the populations before the analysis (Holsinger and Mason-Gamer, 1996).…”

Does Breeding Site Fidelity Drive Phenotypic and Genetic Sub-Structuring of a Population of Arctic Charr?

“…Between-population phenotypic and genotypic variation may be a relatively common phenomenon amongst species with limited dispersal ability, especially those which occupy discrete habitats such as oceanic islands and freshwater systems (Kim et al, 1998). Amongst the freshwater dwelling salmonids, variation in phenotype between populations has been commonly reported (Behnke, 1972(Behnke, , 1986(Behnke, , 1989Klemetsen et al, 2003).…”