Article Abstract:
The evolution of high frequencies of males in an androdioecious plant has been studied and a model developed. It is based on a cross-compatibility advantage of males. Male fertility is frequency-dependent. It was found that a gametophytic self-incompatibility locus linked to a nuclear sex determination focus can be favorable for rare alleles via male function by bringing on frequency-dependent selection. The spread of a female-sterility allele in an hermaphroditic population can be induced. The model can explain male fequencies above 50% in a functionally androdioecious species, if dominance of female-sterility at the sex locus and a few alleles at the self-incompatibiltiy locus exist. This is so even when the advantage in fertility of male phenotype is below two.
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Article Abstract:
Comparative analysis has been carried out using controlled pollinations and alloyzyme markers to study the mating system of the rare woodland shrub Daviesia suaveolnes and its common congener D. mimosoides. Divergence of pollen pool allele frequencies from population frequencies was greater in smaller populations than in larger, in agreement with lower effective size of the male source. Both species require a vector for pollination and have strong self-incompatibility.
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Article Abstract:
Genetic differentiation patterns among six populations of Tachigali, versicolor (Fabaceae: Papilionoideae) in Panama on Barro Colorado Island, have been studied. Analyzing the mating system genetically found that complete outcrossing existed. Results suggest that ecological factors and life history on genetic processes in natural populations are of very great importance.
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