Detecting small-scale genotype–environment interactions in apomictic dandelion (Taraxacum officinale) populations

Authors

  • K. A. McLEOD,

    1. Departments of Botany and Zoology, Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
    2. Department of Environment and Resource Studies, University of Waterloo, Waterloo, Ontario, Canada
    Search for more papers by this author
  • M. SCASCITELLI,

    1. Departments of Botany and Zoology, Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
    Search for more papers by this author
  • M. VELLEND

    1. Departments of Botany and Zoology, Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
    2. Département de Biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
    Search for more papers by this author

Kylie McLeod, Department of Environment and Resource Studies, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1. Tel: +1 519 575 6958; fax: +1 519 746 0292; e-mail: k2mcleod@uwaterloo.ca

Abstract

Studies of genotype × environment interactions (G × E) and local adaptation provide critical tests of natural selection’s ability to counter opposing forces such as gene flow. Such studies may be greatly facilitated in asexual species, given the possibility for experimental replication at the level of true genotypes (rather than populations) and the possibility of using molecular markers to assess genotype–environment associations in the field (neither of which is possible for most sexual species). Here, we tested for G × E in asexual dandelions (Taraxacum officinale) by subjecting six genotypes to experimental drought, mown and benign (control) conditions and subsequently using microsatellites to assess genotype–environment associations in the field. We found strong G × E, with genotypes that performed poorly under benign conditions showing the highest performance under stressful conditions (drought or mown). Our six focal genotypes comprise > 80% of plants in local populations. The most common genotype in the field showed its highest relative performance under mown conditions (the most common habitat in our study area), and almost all plants of this genotype in the field were found growing in mowed lawns. Genotypes performing best under benign experimental conditions were found most frequently in unmown conditions in the field. These results are strongly indicative of local adaptation at a very small scale, with unmown microsites of only a few square metres typically embedded within larger mown lawns. By studying an asexual species, we were able to map genotypes with known ecological characteristics to environments with high spatial precision.

Ancillary