Flower visitors in a natural population of Arabidopsis thaliana

Arabidopsis thaliana is commonly regarded as a self-pollinated plant species. One of the many surprises in population genetic studies of the species was the observation of distinct traces of recombination in the DNA sequences that may be the result of rare outcrossing events. We studied flower visitors in a natural population of the species. Solitary bees, diptera and thrips are among the most frequently observed insects among the surprising diversity of insects visiting flowers of A. thaliana. Assuming that every visit equals an outcrossing event, the outcrossing rate was estimated to be 0.84%. This value falls between estimations of outcrossing rates from molecular data and those of artificial systems. Despite the rather low rate of flower visitation, A. thaliana can no longer be regarded as a completely self-pollinated plant species in the wild. This observation may explain recombination events observed in molecular analyses. Possible pollen transfer between populations due to the mobility of the observed insects should be considered in population genetic analyses.