In plants that rely on animals for pollination, the number of seeds they produce, or their relative fitness, is influenced by pollinator visits and the successful deposition of pollen. The number of visits a plant may receive depends partly on pollinator density as well as on conspecific plant density. But what if a plant happens to grow in a population that is small or has very few pollinators visiting its flowers? Will all the effort put into flowering and attracting pollinators have gone to waste? Some plants, including a bright pink, short-lived, western European herb, have found a way to ensure their future reproductive fitness despite such limitations.
When few pollinators are available, plants are visited less often, and thus do not receive as much pollen and produce fewer seeds than they would under more optimal conditions. Additionally, when plants occur in small populations, pollinator behavior may change, which also influences pollen deposition rates and pollen qualitypollinators may increase the amount of time they spend at each flower on the same plant (depositing more self-pollen) or may switch to foraging on other more abundant flowering species (depositing more hetero-specific pollen).
Some plant species have coped with such unpredictable situations by evolving autonomous selfing, where a flower can self-pollinate without the help of a pollinator. However, there may be variable costs of inbreeding depression associated with relying entirely on this mode of reproduction.
Rein Brys and colleagues (from the Terrestrial Ecology Unit, University of Ghent, Belgium and the Plant Ecology Unit, University of Leuven, Belgium) investigated to what extent population size and pollinator availability affected the number of seeds that were produced via self-pollination in the monocarpic herb Centaurium erythraea in a highly fragmented dune area in Belgium. They published their findings in the November issue of the Amer
|Contact: Richard Hund|
American Journal of Botany