In this paper, we evaluate patterns of fruit eating and seed dispersal
in monkeys and apes and draw an important distinction between 1) the
ecological consequences of primates as seed dispersers and 2) the evol
utionary implications of primates on the seed and fruit traits of the
plant species they exploit. In many forest communities, primates act a
s both seed predators and seed dispersers and are likely to have an im
portant ecological impact on patterns of forest regeneration and tree
species diversity. Evidence from Kibale National Park, Uganda, and Man
u National Park, Peru, as well as several other South American sites i
ndicates that monkeys and apes display a wide range of fruit-processin
g behaviors, including spitting seeds, dropping seeds, masticating see
ds, and swallowing seeds. Differences in consumer body size, diet, ran
ging patterns, and oral and digestive morphology result in different p
atterns in the distance and distribution of seeds from the parent plan
t. In the case of South American monkeys, for example, despite their r
elatively small body size, platyrrhines were found to exploit larger f
ruits and swallow larger seeds on average than did Old World monkeys a
nd apes of the Kibale forest. We found little evidence to support the
existence of a coevolutionary relationship between a single or set of
primate dispersers and the particular plant species they disperse. Thi
s is due to variability in the manner in which monkeys and apes select
fruits and treat seeds, the fact that many species of primates and no
nprimates exploit and disperse the same fruit species, and the fact th
at extremely high levels of postdispersal seed, seedling, and sapling
mortality serve to dilute the influence that any primate species may h
ave on the recruitment of the next generation of adult trees. It is ap
parent that many primate lineages exhibit dental, digestive, and/or se
nsory adaptations that aid in the exploitation of particular food type
s and that many lineages of flowering plants have evolved characterist
ics of fruits and seeds that facilitate seed dispersal. However, in Li
ght of currently available data, we argue that these represent evoluti
onary rather than more strictly defined coevolutionary relationships.
(C) 1998 Wiley-Liss, Inc.