Going Farther with Sex

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Science  26 Jun 2009:
Vol. 324, Issue 5935, pp. 1619
DOI: 10.1126/science.324_1619a

Plant mating systems are under pressure to produce the most and the best offspring (seeds) and to offer them the greatest opportunity to thrive in the absence of competition by dispersal. Self-pollination is one means by which plants can maximize their reproductive potential, but how it relates to dispersal is unclear. Plants that cannot self-fertilize have been linked to lower dispersal rates because it has been thought that if they were to disperse widely, the lack of a nearby pollen source would result in reproductive failure. Despite this theory, it has been noted that invasive species, those with fleshy fruits, and island colonizers—all of which typify plants with good dispersal systems—tend to have mating systems that separate the sexes or select against self-pollination.

Cheptou and Massol construct a metapopulation model that captures the evolution of dispersal and self-fertilization in environments defined by stochastic pollen limitation. Their calculations show that self-fertilization associates with no dispersal and that outcrossing goes with dispersal, contrary to some previous postulates. Based on these results, they explain the overrepresentation of dioecious plants (those with only male or female individuals) in flora, such as papaya, that have colonized islands.

Am. Nat. 174, 46 (2009).

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