MATING SYSTEMS, GENETIC DIFFERENTIATION AND SPECIATION IN TROPICAL RAIN-FOREST PLANTS

The debate about microevolutionary processes resulting in speciation in tropical woody plants has been largely based on different and contrasting perceptions about their modes of reproduction. The research during the last twenty years has shown that most tropical woody plants are strongly outcrossed. Recent quantitative estimates of mating systems and analyses of population genetic structures, respectively, indicate that the rates of outcrossing are high and there is considerable genetic diversity within populations. Although data on mating systems and population genetic structure have not settled the issue of speciation modes in tropical woody plants, empirical studies have provided little support for the notions about prevalence of selfing and a high level of inbreeding. Further progress in understanding speciation should come from the study of genera with a large number of sympatric species. Two profitable areas of research might involve the evaluation of the part played by plant-pollinator interactions in speciation and the documentation of the levels of gene flow and genetic differentiation among populations.