Phylogeography of Dalton's Mouse (West Africa)

Next Monday, Catherine will present a paper on phylogeography of a small rodent: the Dalton's Mouse in West Africa. In this paper, the authors (1) found discrepancies between recognized morphospecies and phylogenetic results, (2) found evidence of refuges in the region, (3) found an effect of biogeographic barriers, (4) discussed the taxonomic status (biological species) of the different lineages and (5) found support for historic introgression events between lineages. Thanks Catherine.

From J. BRYJA, L. GRANJON, G. DOBIGNY, H. PATZENHAUEROVA, A. KONECNY, J.M. DUPLANTIER, P. GAUTHIER, M. COLYN, L. DURNEZ, A. LALIS and V. NICOLAS; Molecular Ecology (2010) doi: 10.1111/j.1365-294X.2010.04847.x

Title: Plio-Pleistocene history of West African Sudanian savanna and the phylogeography of the Praomys daltoni complex (Rodentia): the environment/geography/genetic interplay

Abstract.

Rodents of the Praomys daltoni complex are typical inhabitants of the Sudanian savanna ecosystem in western Africa and represent a suitable model for testing the effect s of Quaternary climatic oscillations on extant genetic variation patterns. Phylogeographical analyses of mitochondrial DNA sequences (cytochrome b) across the distribution range of the complex revealed several well-defined clades that do not support the division of the clade into the two species currently recognized on the basis of morphology, i.e. P. daltoni (Thomas, 1892) and Praomys derooi (Van der Straeten & Verheyen 1978). The observed genetic structure fits the refuge hypothesis, suggesting that only a small number of populations repeatedly survived in distinct forest-savanna mosaic blocks during the arid phases of the Pleistocene, and then expanded again during moister periods. West African rivers may also have contributed to genetic differentiation, especially by forming barriers after secondary contact of expanding populations. The combination of three types of genetic markers (mtDNA sequences, microsatellite loci, cytogenetic data) provides evidence for the presence of up to three lineages, which most probably represent distinct biological species. Furthermore, incongruence between nuclear and mtDNA markers in some individuals unambiguously points towards a past introgression event. Our results highlight the importance of combining different molecular markers for an accurate interpretation of genetic data.