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. 2005 Apr;95(5):879-86.
doi: 10.1093/aob/mci094. Epub 2005 Feb 10.

Preferences of pollinators and herbivores in gynodioecious Geranium sylvaticum

Eija Asikainen  1 , Pia Mutikainen
Affiliations

Preferences of pollinators and herbivores in gynodioecious Geranium sylvaticum

Eija Asikainen et al. Ann Bot. 2005 Apr.

Abstract

Background and aims: For the maintenance of gynodioecy (i.e. the coexistence of female and hermaphroditic plants), females need to compensate for the lack of pollen production through higher seed production or better progeny quality compared to hermaphrodites. In Geranium sylvaticum, females produce more seeds per flower than hermaphrodites. This difference in seed production might be modified by biological interactions with pollinators and herbivores that may favour one sex and thus affect the maintenance of gynodioecy.

Methods: Sexual dimorphism in flower size and flowering phenology, and in attractiveness to pollinators, pre-dispersal seed predators and floral herbivores were examined in natural populations of G. sylvaticum.

Key results: Pollinators preferred hermaphrodites 25 % more often than females in two of the three study populations, and floral herbivores attacked hermaphrodites 15 % more often than females in two of the six study populations. These preferences might be explained by the larger flower size of hermaphrodites. In contrast, seed predators did not prefer either sex.

Conclusions: The data suggest that pollinator preference does not benefit females, whereas the higher floral herbivory of hermaphrodites might enhance the maintenance of females in G. sylvaticum. Thus, although the data support the view that ecological factors may contribute to the maintenance of gynodioecy, they also suggest that these contributions may vary across populations and that they may function in opposite directions.

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Figures

F<sc>ig</sc>. 1.
Fig. 1.
Petal length (mean ± s.e.) of female and hermaphroditic plants from 11 populations (P1–P11) of the gynodioecious Geranium sylvaticum.
F<sc>ig</sc>. 2.
Fig. 2.
Proportion of females and hermaphrodites of all flowering plants, and proportion of plants flowering during the growing season in three populations of the gynodioecious Geranium sylvaticum: (A) P3, (B) P8 and (C) P9.
F<sc>ig</sc>. 3.
Fig. 3.
Proportion of seeds predated (%) in females and hermaphrodites in ten populations of the gynodioecious Geranium sylvaticum in (A) 2001 and (B) 2002.
See this image and copyright information in PMC

References

    1. Alonso C. 2003. Herbivores do not discriminate between leaves of female and hermaphrodite individuals of gynodioecious Daphne laureola (Thymelaeaceae). Oikos 101: 505–510.
    1. Ashman T.-L. 2000. Pollinator selectivity and its implications for the evolution of dioecy and sexual dimorphism. Ecology 81: 2577–2591.
    1. Ashman T.-L. 2002. The role of herbivores in the evolution of separate sexes from hermaphroditism. Ecology 83: 1175–1184.
    1. Ashman T.-L, Stanton ML. 1991. Seasonal variation in pollination dynamics of sexually dimorphic Sidalcea oregana ssp. spicata (Malvaceae). Ecology 72: 993–1003.
    1. Asikainen E, Mutikainen P. 2003. Female frequency and relative fitness of females and hermaphrodites in gynodioecious Geranium sylvaticum (Geraniaceae). American Journal of Botany 90: 226–234. - PubMed

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