XVI International Botanical Congess
We examined levels of allozyme diversity and genetic structure of five sympatric species of cactus. Stenocereus griseus, Cereus repandus, Pilosocereus lanuginosus, Pereskia guamacho and Melocactus curvispinus. All but M. curvispinus are self-incompatible. All species are animal pollinated and dispersed, but they differ in pollination and seed dispersal syndroms. All of them have relatively high percentages of polymorphic loci, number of alleles per polymorphic locus and heterozygosity values at the species (P = 89.5 - 100.0 %, AP= 3.5 - 3.8, He = 0.15 - 0.26) and population level (P = 45.3 - 76.1 %, AP = 2.2 - 2.7, He = 0.10 - 0.23). Obligate outcrossing species are less genetically subdivided (Gst = 0.05 - 0.12) than the only self-compatible species (Gst = 0.21). Our results suggest that the bat pollination/seed dispersal system may play an important role in decreasing population structure in cactus species when compared to alternative gene vector systems.