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Given
the short life span of the adult pollinating fig wasps and the lack
of synchrony of fig production, how then is the relationship
maintained? Usually on emergence the female wasps have to leave the
tree they bred on, because the figs in a particular crop are
normally all at the same stage of development. Some Ficus
species, however, have figs at different stages of development
within the same crop and in these cases the female wasp has only to
fly a short distance to locate a receptive fig. The cycling of the
mutualism can, therefore, continue on the same tree. More commonly
the cycling phenomenon relies on the presence of a suitably sized
population of trees of a particular species in a given area, so that
somewhere within the population there will be a tree with figs that
are receptive for pollination. The lack of synchrony in fig crop
production between trees is an essential trait to ensure this. If
all the trees in a population produced figs at the same time, the
fig wasp population would die out. Local extinctions of wasps do
occur, when they are not able to locate a tree with figs in the
receptive phase, and there will also be abortions of fig crops that
pollinators have not managed to locate. Nevertheless, in the larger
picture this is a very successful interaction, which is borne out by
the high diversity of both fig trees and fig wasps.
Illustration © Simon van Noort |
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