POLLINATOR LIMITATION OF FIG TREE REPRODUCTION ON THE ISLAND OF ANAK-KRAKATAU (INDONESIA)

Each species of fig tree (Ficus spp., Moraceae) is pollinated by its own unique species of fig wasp (Agaonidae). We examined pollination rates and functional sex-ratios among the fig trees that have colonized the recently formed volcanic island of Anak Krakatau. Four fruiting Ficus species were present. Two of these, F. fistulosa and F. hispida, occurred in small numbers and were receiving sufficient pollinators. In contrast, pollination rates were estimated at 8 1 percent for F. septica (80 trees fruiting) and only 18 percent for F. fulva (approximately 200 trees fruiting). Both these species had higher pollination rates on the older islands in the Krakatau group. Their functional sex ratios (the proportion of male/female trees bearing fruits) did not differ significantly from 50:50, and there were indications of preferential pollination of female figs. The shortage of pollinators (and therefore mature figs) on Anak Krakatau is likely to have consequences for the frugivorous birds and bats on the island.