Evidence of environmental niche differentiation in the striped mouse (Rhabdomys sp.): inference from its current distribution in southern Africa

Authors

  • Christine N. Meynard,

    1. INRA, UMR CBGP (INRA/IRD/Cirad/Montpellier SupAgro), Campus international de Baillarguet, CS 30016, F-34988 Montferrier-sur-Lez cedex, France
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  • Neville Pillay,

    1. School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa
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  • Manon Perrigault,

    1. Institut des Sciences de l’Evolution, UMR 5554, Université Montpellier 2, C.C. 065, Montpellier cedex 5 34095, France
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  • Pierre Caminade,

    1. Institut des Sciences de l’Evolution, UMR 5554, Université Montpellier 2, C.C. 065, Montpellier cedex 5 34095, France
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  • Guila Ganem

    1. School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa
    2. Institut des Sciences de l’Evolution, UMR 5554, Université Montpellier 2, C.C. 065, Montpellier cedex 5 34095, France
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  • This study is part of an international program of scientific collaboration financed by the NRF (South Africa) and the CNRS (France): PICS n°4841. We have also benefited from financial and scientific support from the GDRI 191 and the University of the Witwatersrand.

  • Ecology and Evolution 2012; 2(5): 1008–1023

Christine N. Meynard, INRA, UMR CBGP (INRA/IRD/Cirad/Montpellier SupAgro), Campus international de Baillarguet, CS 30016, F-34988 Montferrier-sur-Lez cedex, France. Tel: +33-4 30 63 04 29; Fax: (33) 4 99 62 33 45; E-mail: Christine.Meynard@supagro.inra.fr

Abstract

The aim of this study was to characterize environmental differentiation of lineages within Rhabdomys and provide hypotheses regarding potential areas of contact between them in the Southern African subregion, including the Republic of South Africa, Lesotho, and Namibia. Records of Rhabdomys taxa across the study region were compiled and georeferenced from the literature, museum records, and field expeditions. Presence records were summarized within a 10 × 10 km grid covering the study area. Environmental information regarding climate, topography, land use, and vegetation productivity was gathered at the same resolution. Multivariate statistics were used to characterize the current environmental niche and distribution of the whole genus as well as of three mitochondrial lineages known to occur in southern Africa. Distribution modeling was carried out using MAXENT in order to generate hypotheses regarding current distribution of each taxa and their potential contact zones. Results indicate that the two species within Rhabdomys appear to have differentiated across the precipitation/temperature gradient present in the region from east to west. R. dilectus occupies the wettest areas in eastern southern Africa, while R. pumilio occupies the warmer and drier regions in the west, but also penetrates in the more mesic central part of the region. We provide further evidence of environmental differentiation within two lineages of R. dilectus. Contact zones between lineages appear to occur in areas of strong environmental gradients and topographic complexity, such as the transition zones between major biomes and the escarpment area where a sharp altitudinal gradient separates coastal and plateau areas, but also within more homogeneous areas such as within grassland and savannah biomes. Our results indicate that Rhabdomys may be more specialized than previously thought when considering current knowledge regarding mitochondrial lineages. The genus appears to have differentiated along two major environmental axes in the study region, but results also suggest dispersal limitations and biological interactions having a role in limiting current distribution boundaries. Furthermore, the projection of the potential geographic distribution of the different lineages suggests several contact zones that may be interesting study fields for understanding the interplay between ecological and evolutionary processes during speciation.

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