BREEDING SYSTEMS OF TREES IN A TROPICAL WET FOREST

The breeding systems of tree species of a tropical lowland wet forest were investigated as a first step towards ascertaining the level of inbreeding. Approximately 65% of the species in the community were found to be hermaphroditic; the frequencies of monoecious and dioecious species were 15% and 20% respectively. Controlled pollinations were made on 25 hermaphroditic species; self-incompatibility was found in 88% of these species. The self-incompatibility systems, however, broke down frequently either due to experimental techniques and/or due to inherent physiological-genetic factors. The majority of species appeared to display the gametophytic type of incompatibility system with pollen tubes from the self-pollen growing up to the ovules. Although the majority of tropical trees appear to be outcrossed, the possibility that they are inbred due to small effective population size remains to be eliminated. © 1979 Taylor & Francis Group, LLC.