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CONSEQUENCES OF VEGETATIVE HERBIVORY FOR MAINTENANCE OF INTERMEDIATE OUTCROSSING IN AN ANNUAL PLANT
Author(s) -
Steets Janette A.,
Hamrick James L.,
Ashman Tia-Lynn
Publication year - 2006
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2006)87[2717:covhfm]2.0.co;2
Subject(s) - outcrossing , selfing , biology , mating system , herbivore , mating , pollinator , ecology , obligate , pollination , botany , population , pollen , demography , sociology
Given the occurrence of mixed mating systems among plants, a general mechanism explaining the evolution and maintenance of this condition is needed. Although numerous theoretical models predict mixed mating to be evolutionarily stable, conditions favoring intermediate selfing are often stringent and have limited applicability. Here we investigated the role of vegetative herbivory, a ubiquitous biotic factor limiting plant reproduction, in the mating system expression of Impatiens capensis (Balsaminaceae), a species with an obligate mixed‐mating system (individuals produce both selfing, cleistogamous, and facultatively outcrossing, chasmogamous flowers). Herbivory reduced proportional chasmogamous reproduction partially, but not entirely, through a reduction in plant size and the strength of this effect varied among replicates. Herbivory decreased geitonogamous selfing in chasmogamous flowers via several mechanisms including reduced chasmogamous flower display size and pollinator visitation rate and altered pollinator composition. Overall, herbivory caused a decrease in whole‐plant outcrossing, indicating that the effects of herbivory on proportional chasmogamous reproduction, which favor selfing, outweigh the effects on chasmogamous outcrossing rate, which favor outcrossing. Not only do our findings unravel the mechanisms underlying herbivore‐mediated changes in the mating system, but they also point to the role of natural enemies in contributing to the maintenance of a mixed mating system.