THE BREEDING STRUCTURE OF A TROPICAL KEYSTONE PLANT RESOURCE

Despite the recognized importance of maintaining viable populations of keystone plant resources in tropical wildlife parks and forested pres erves, the critical question of what constitutes effective breeding un its of these species has not been directly addressed. Here we use pate rnity analysis techniques to reconstruct the genotypes of pollen donor trees and to estimate pollen dispersal distances and breeding populat ion size parameters for Panamanian populations of seven species of mon oecious strangler figs (Ficus, Moraceae), a particularly widespread an d influential group of keystone producers(1-3). Despite the minute siz e (1-2 mm) and short lifespan (2-3 d) of the species-specific wasp pol linators (Agaonidae, Chalcidoidea), pollen dispersal was estimated to occur routinely over distances of 5.8-14.2 km between widely spaced ho st trees, As a result of such extensive pollen movement, breeding unit s of figs comprise hundreds of intermating individuals distributed ove r areas of 106-632 km(2), an order of magnitude larger than has been d ocumented for any other plant species. Moreover, these results should be generalizable to the 350 or so monoecious fig species that share th is pollination system(4). The large areal extent of breeding units of these keystone plant resources has important implications for our unde rstanding of both the evolution of tropical biodiversity and its maint enance by applied conservation efforts.