RUI: The Ecological Consequences of Sexual and Apomictic Reproduction

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Experimental tests will be carried out using an alpineplant, >Antennaria> >parvifolia>. >Antennaria> is ideal for carryingout these tests, because populations consist of two kinds ofindividuals, morphologically similar but differing in their modeof reproduction. Some plants are sexual, requiring pollen tofertilize their seeds, and producing genetically variableoffspring. Others are asexual (apomictic), requiring no pollenand producing genetically identical offspring. At some sites,both types coexist in the dame populations; at others, only onetype or the other is present. In mixed populations, adultindividuals of the two types are about equally common. However,the seed production of asexual females exceeds that of sexualfemales by a factor of two, as predicted. Thus, thisexperimental system epitomizes the paradox we seek to explain:why are sexual individuals so common when they have areproductive disadvantage? In addition to increasing our understanding of a very basicbiological phenomenon, this work also has applications foragriculture and forestry. Agricultural plantings are typicallygenetically homogeneous, and any disadvantages associated withasexual reproduction in >Antennaria> may also exist in thesegenetically uniform plantings. Research findings may lead torecommendations for the design of agricultural systems that mightreduce the amount of fertilizer and pesticide inputs necessaryfor success.