Effects of herkogamy and inbreeding on the mating system of Mimulus luteus in the absence of pollinators
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2009-08-23Metadata
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Carvallo, Gastón
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Effects of herkogamy and inbreeding on the mating system of Mimulus luteus in the absence of pollinators
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Abstract
Self-pollination mechanisms are often invoked to explain plant reproduction in
environments devoid of pollinators. However, populations may evolve a diverse variety of
strategies depending on the ecological context of pollination. In this study we examined
the pollination environment, inbreeding depression, and herkogamy of Mimulus luteus
(Phrymaceae) in two consecutive years in an attempt to evaluate the extent to which these
factors determine the current level of autogamy in this population. Results indicate that
pollinators were almost absent in the study site in 2005 and 2006. Likewise, no evidence of
significant inbreeding depression for seed production and seed germination was detected in
the 2 years. Because M. luteus presents hermaphrodite flowers with ‘movement herkogamy’
(touch-sensitive stigmata that close upon contact), and anther–stigma separation, we
evaluated the role of these traits in self-fertilization. First, we assessed the effects of pollen
source (self- and xenogamous pollen, and control solution) on stigmata dynamics after
pollen deposition, and seed production. We observed that stigmata that received pollen
(self- and xenogamous hand-pollinated) remained closed for a longer time than flowers that
received no pollen (control flowers). Seed production, however, was unaffected by pollen
source, indicating that movement herkogamy does not prevent self-fertilization in
this population. Second, a phenotypic selection analysis revealed that seed production
increased with a reduction of anther–stigma separation in absence of pollinators (bagged
flowers), suggesting that low herkogamy levels are promoted in this population. Our results
indicate that lack of inbreeding depression, ineffective movement herkogamy, and selection
against anther–stigma separation are factors that may contribute to the prevalence of
autogamous reproductive mechanisms when M. luteus faces environments with scarce
mating opportunity.
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Artículo de publicación ISI
Patrocinador
FONDECYT 1050199 and ACT 34/2006 grants
to R. M., and CONICYT 21050243 and CMEB P02-051-F ICM scholarships to G.O.C supported this
research.
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EVOLUTIONARY ECOLOGY, Volume: 24, Issue: 2, Pages: 509-522, 2010
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