reflect the extravagance with which Xanthosoma
robustum advertises its inflorescences; that extrava-
gance reflects the importance of attracting pollinators
among patches that are transient and separated by
dense forest.
Acknowledgments I acknowledge with gratitude
permission to study aroids on land owned by Bill
Calvert, Patricia and Michael Fogden, and the Tropi-
cal Science Center, and financial support from the
Organization for Tropical Studies, Phi Beta Kappa, the
Center for Latin American Studies, and Sigma XL I
thank Tomas and Lindi Guindon for their hospitality
during my field seasons, Peter Feinsinger and other
members of SuCoPla for discussions about pollina-
tion, Jerome Casas and Maria Goldwasser for com-
ments on the manuscript, and Bastiaan Meeuse for
sparking my interest in aroid inflorescences.FIG POLLINATION AND SEED-DISPERSAL MUTUALISMS
Judith L* Bronsteinhe mutualism between figs (Ficus spp.,
Moraceae) and their obligate pollinator wasps
(Hymenoptera: Chalcidoidea: Agaoninae) is
one of the best-known plant-animal interactions and
one that has become emblematic of the tropics. About
750 species of figs exist, almost all of which have
unique pollinators, making this one of the most spe-
cies-specific and tightly coevolved mutualisms. Figs
are also involved in mutualistic interactions with
vertebrate seed-dispersers. In contrast to pollination,
fig seed dispersal is generalized.
There are five fig species in Monteverde: Ficus
pertusa, F. tuerkheimii, F. velutina, F, crassiuscula,
and F. yoponensis (Wiebes 1995). The reproductive
biology of only one of these figs (F. pertusa) has been
studied in depth in Monteverde. Ficus yoponensis has
been given extensive attention on Barro Colorado Is-
land, Panama (Milton et al. 1982, Herre 1989, Windsor
et al. 1989). The others remain unstudied. Here, I
focus on F. pertusa, which is fairly typical of the
roughly 350 species of figs with monoecious breed-
ing systems (Bronstein 1992).
Ficus pertusa trees are common throughout Monte-
verde and are often left standing as shade trees when
forest is cleared for pasture. Individual trees flower
unpredictably but usually once to three times each
year, initiating up to several hundred thousand inflo-
rescences (figs) in each episode. Nearly all the polli-
nators (female Pegoscapus silvestrii) arrive during a
2-3-day period, apparently in response to species-
specific volatiles released when the roughly 200 fe-
male florets within each fig are receptive (Bronstein
1987, Anstett et al. 1996). The millimeter-long,
pollen-carrying wasps squeeze into the small (1 cm)
spherical figs, gaining access to the female florets but
becoming fatally trapped in the process. Florets vary
greatly in style length and are staggered so that stig-
mas form a uniform surface within the fig cavity. Once
within the fig, a wasp first actively deposits pollen
on the stigmatic surface. She then inserts her oviposi-
tor down the length of a number of styles to lay eggs.
If she reaches the ovary at the base of a given style,
she deposits one egg. One of her offspring will de-
velop within that ovary, feeding on the seed that
starts to develop as a result of the pollen she has lain
down. If the style is too long relative to her oviposi-
tor, she does not lay an egg, which allows a seed to
develop undisturbed.
Over the next 2 months, seeds and seed-eating fig
wasp larvae develop within the figs. Mature males
then emerge from the ovaries in which they have de-
veloped, search out the still-developing females, and
mate with them. Males then chew an exit hole back
through the wall of the fig. Females emerge from the
ovaries and seek out the handful of newly mature
anthers scattered among the female florets in their
natal fig. They rip the anthers open and pack pollen
into special pockets on their abdomens. Inseminated
and pollen laden, they depart their natal figs in
search of a receptive fig in which to lay their eggs.
In F. pertusa, all figs on a single tree develop in tight
synchrony, whereas different trees in a population
flower out of synchrony with each other (Bronstein
1987,1988a). The wasps must therefore locate another
tree in the correct phenological phase to reproduce.
Adult fig wasps live only a day or two in the wild and
do not feed; mortality during transit between trees is
undoubtedly high.
Major gaps remain in our understanding of F. per-
tusa pollination biology, and of fig-pollinator inter-
actions in general (Janzen 1979, Bronstein 1992, Herre
1996). It is unclear why fig wasps do not leave enough
offspring to destroy every seed within figs, that is, why
they are mutualists at all. It is believed that figs limit(^271) Plant-Animal Interactions
T