The interactive effects of herbivory and mixed mating for the population dynamics of Impatiens capensis

In this study, we examine the demographic consequences of mixed mating and explore the interactive effects of vegetative herbivory and mating system for population dynamics of Impatiens capensis, a species with an obligate mixed mating system (i.e., individuals produce both obligately selfing cleist...

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Bibliographic Details
Published inThe American naturalist Vol. 170; no. 1; p. 113
Main Authors Steets, Janette A, Knight, Tiffany M, Ashman, Tia-Lynn
Format Journal Article
LanguageEnglish
Published United States 01.07.2007
Subjects
Animals
Breeding
Feeding Behavior
Germination
Impatiens - embryology
Impatiens - growth & development
Impatiens - physiology
Insecta - physiology
Population Density
Population Dynamics
Seeds - growth & development
Seeds - physiology
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Summary:In this study, we examine the demographic consequences of mixed mating and explore the interactive effects of vegetative herbivory and mating system for population dynamics of Impatiens capensis, a species with an obligate mixed mating system (i.e., individuals produce both obligately selfing cleistogamous and facultatively outcrossing chasmogamous flowers). In two natural populations, we followed seeds derived from cleistogamous and chasmogamous flowers subject to different herbivory levels throughout their life cycle. Using a mating system-explicit projection matrix model, we found that mating system types differed in important vital rates. Cleistogamous individuals had higher rates of germination than did chasmogamous individuals, whereas chasmogamous individuals expressed a fecundity advantage over cleistogamous individuals. In addition, population growth was most sensitive to changes in vital rates of cleistogamous individuals, indicating the demographic importance of selfing for these populations. Herbivory also had demographic consequences; a 33%-49% reduction in herbivory caused the population growth rates to increase by 104%-132%, primarily because of effects on vital rates of selfed individuals. Our results not only uncover a novel consequence of mating system expression, that is, mating system influences population dynamics, but also shed light on the role of herbivores in maintaining mixed mating.
ISSN:1537-5323
DOI:10.1086/518178