Plant-Animal Interactions
K. Greg Murray
Sharon Kinsman
Judith L. BronsteinThe term "plant-animal interactions" includes a di-
verse array of biologically important relationships.
Plant-herbivore relationships (in which an animal
feeds on whole plants or parts of them) are examples
of exploitation, because one species benefits from the
interaction while the other suffers. Plant-pollinator and
plant-seed disperser relationships (in which animals
disperse pollen or seeds, usually in return for a food
reward) are examples of mutualisms because they are
beneficial to both parties. Another class of plant-ani-
mal mutualisms involves plants that provide nesting
sites and/or food rewards to ants, which often protect
the plant from herbivores or competing plants. Plant-
pollinator and plant-seed disperser mutualisms prob-
ably originated as cases of exploitation of plants by
animals (Thompson 1982, Crepet 1983, Tiffney 1986).
Many of the distinctive plant structures associated with
animal-mediated pollen and seed dispersal (e.g., flow-
ers, nectaries, attractive odors, fleshy fruit pulp, and
thickened seed coats) presumably evolved to attract
consumers of floral or seed resources while prevent-
ing them from digesting the pollen or seeds.
Until the mid-1970s, ecologists paid relatively little
attention to the potential roles played by plant-animal
mutualisms in structuring ecological communities.
Competition and predator-prey interactions were
more common subjects. Botanists had described the
characteristics of the plant and animal players in
pollination and seed dispersal mutualisms (Knuth
1906, 1908, 1909, Ridley 1930, van der Pijl 1969,
Faegri and van der Pijl 1979), but these descriptive
works did not fully examine plant-animal mutualisms
in the context of communities. The opportunity to
work in the neotropics, facilitated by the Organiza-
tion for Tropical Studies (OTS), the Smithsonian
Tropical Research Institute (STRI), and other institu-
tions, attracted the attention of temperate-zone ecolo-
gists to the mutualisms that are much more conspicu-
ous components of tropical systems than of temperate
ones (Wheelwright 1988b).
Plant-pollinator interactions have attracted more
attention in Monteverde than plant-frugivore interac-
tions, and plant-herbivore interactions remain con-
spicuously understudied. This imbalance probably
reflects the interests of those who first worked at
Monteverde and later returned with their own stu-
dents, rather than differences in the significance of the
interactions at Monteverde or elsewhere. Aside from8