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Relative importance of habitat connectivity in shaping the genetic profiles of two southern African elephant-shrews

Authors

  • Hanneline A. Smit,

    1. Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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  • Johan Watson,

    1. Biodiversity Research, Free State Department of Economic Development, Tourism and Environmental Affairs, Private Bag X20801, Bloemfontein 9300, South Africa
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  • Bettine Jansen van Vuuren

    Corresponding author
    1. Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
    2. Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
      Bettine Jansen van Vuuren, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
      E-mail: bjvv@sun.ac.za
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Bettine Jansen van Vuuren, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
E-mail: bjvv@sun.ac.za

Abstract

Aim  When interpreting genetic patterns across a landscape it is surprisingly difficult to disentangle the effects of landscape connectivity from those of species biology. Here, the spatial distributions of genetic variation of two sympatric elephant-shrew species, the western rock elephant-shrew (Elephantulus rupestris) and the round-eared elephant-shrew (Macroscelides proboscideus), are determined and compared. We selected these species because they have similar biologies but differ markedly in habitat use, the rationale being that differences in their genetic structure should be a result largely of landscape variables directly or indirectly affecting dispersal rather than of the biology of the species.

Location  South Africa and Namibia.

Methods  Mitochondrial sequence data (control region and cytochrome b) were used to describe the phylogeographic structure of these elephant-shrew species across their distribution. To determine whether genetic variation is significantly structured, spatial analyses of molecular variation were performed. Isolation-by-distance versus alternative patterns of genetic structure was investigated using a Mantel test.

Results  Our analyses indicated an overall structured genetic profile for E. rupestris, a species closely associated with rocky outcrops. This was in contrast to a pattern mostly of isolation-by-distance across the distribution of M. proboscideus, a species found on gravel plains.

Main conclusions  Specific landscape features will differentially affect gene flow (both historical and current), and therefore also the spatial genetic structure, of species with markedly different habitat requirements. The genetic profiles for the two species included here support predictions based on the connectivity of their respective occupied habitats. The results also support the more general prediction that species with a naturally clustered distribution (such as E. rupestris) should have a more structured genetic pattern than those having a more continuous distribution (M. proboscideus).

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