The predominance of outcrossing despite the substantial transmission advantage of self-fertilization remains a paradox. Theory suggests that selection can favor outcrossing if it enables the production of offspring that are less susceptible to pathogen attack than offspring produced via self-fertilization. Thus, if pathogen pressure is contributing to the maintenance of outcrossing in plants, there may be a positive correlation between the number of pathogen species attacking plant species and the outcrossing rate of the plant species. We tested this hypothesis by examining the association between outcrossing rate and the number of fungal pathogen species that attack a large, taxonomically diverse set of seed plants. We show that plant species attacked by more fungal pathogen species have higher outcrossing rates than plants with fewer enemies. This relationship persists after correcting for study bias among natural and agricultural species of plants. We also accounted for the nested hierarchy of relationships among plant lineages by conducting phylogenetically independent contrasts (PICs) within genera and families that were adequately represented in our dataset. A meta-analysis of the correlation between pathogen and outcrossing PICs shows that there is a positive correlation between pathogen species number and outcrossing rates. This pattern is consistent with the hypothesis that pathogen-mediated selection may contribute to the maintenance of outcrossing in species of seed plants.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 58 • No. 11