Open AccessGenetic introgression as a potential to widen a species' niche: Insights from alpine Carex curvula
Author(s) -
Philippe Choler,
Brigitta Erschbamer,
Andreas Tribsch,
Ludovic Gielly,
Pierre Taberlet
Publication year - 2003
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.2237235100
Subject(s) - introgression , biology , ecology , carex , range (aeronautics) , habitat , taxon , gene flow , alpine plant , ecological niche , niche , abundance (ecology) , population , niche differentiation , genetic variation , biochemistry , materials science , demography , sociology , gene , composite material
Understanding what causes the decreasing abundance of species at the margins of their distributions along environmental gradients has drawn considerable interest, especially because of the recent need to predict shifts in species distribution patterns in response to climatic changes. Here, we address the ecological range limit problem by focusing on the sedge, Carex curvula, a dominant plant of high-elevation grasslands in Europe, for which two ecologically differentiated but crosscompatible taxa have been described in the Alps. Our study heuristically combines an extensive phytoecological survey of alpine plant communities to set the niche attributes of each taxon and a population genetic study to assess the multilocus genotypes of 177 individuals sampled in typical and marginal habitats. We found that ecological variation strongly correlates with genetic differentiation. Our data strongly suggest that ecologically marginal populations of each taxon are mainly composed of individuals with genotypes resulting from introgressive hybridization. Conversely, no hybrids were found in typical habitats, even though the two taxa were close enough to crossbreed. Thus, our results indicate that genotype integrity is maintained in optimal habitats, whereas introgressed individuals are favored in marginal habitats. We conclude that gene flow between closely related taxa might be an important, although underestimated, mechanism shaping species distribution along gradients.