Making the most of your pollinators: An epiphytic fig tree encourages its pollinators to roam between figs

Ficus species are characterised by their unusual enclosed inflorescences
(figs) and their relationship with obligate pollinator fig wasps
(Agaonidae). Fig trees have a variety of growth forms, but true epiphytes
are rare; one example is the Ficus deltoidea of South-east Asia.
 Presumably as an adaptation to epiphytism, inflorescence design
in this species is exceptional, with very few flowers in female
(seed-producing) figs and unusually large seeds. Figs on male (pollinator
offspring-generating) trees have many more flowers. Many fig wasps
pollinate one fig each, but because of the low number of flowers per fig,
efficient utilization of F. deltoidea’s pollinators depends on pollinators
entering several female figs. We hypothesised that it is in the interest
of the plants to allow pollinators to re-emerge from figs on both male and
female trees and that selection favours pollinator roaming because it
increases their own  reproductive success. Our manipulations of
Blastophaga sp. pollinators in a Malaysian oil palm plantation confirmed
that individual pollinators do routinely enter several figs of both sexes.
Entering additional figs generated more seeds per pollinator on female
trees and more offspring on male trees. Pollinator offspring sex ratios in
subsequently-entered figs were often less female-biased than in the first
figs they entered, which reduced their immediate value to male trees
because only female offspring carry their pollen.  Small numbers
of large seeds in female figs of epiphytic F. deltoidea may reflect
constraints on overall female fig size, because pollinator exploitation
depends on mutual mimicry between male and female figs.