The floristic structure of the habitat is one of the determinants of the quantity and quality of food available to a local population of primates. Primates, in turn, can influence this structure as they interact differentially with the plants they feed on, for example, preying on or dispersing their seeds (Peres, 1991; Lopes & Ferrari, 1994).
Primates are important seed dispersers for many fruit species (eg, Poulsen et al., 2001; Stevenson et al., 2002; Wehncke et al., 2003). However, some authors (eg Janzen 1983; Schupp 1993) argue that observations on the rate of fruit removal by primates and verification of seed viability after passage through the digestive tract of animals assess only the amount of dispersed seeds, while the quality of dispersion depends on the location and pattern of seed deposition. Howe (1980, 1989, 1993, Howe et al., 1985) argues that primates are inefficient dispersers because they deposit seeds in high concentrations (in faeces), leading to a high probability of predation by rodents, and even a high rate. seedling mortality due to competition.
Chapman (1989) found a high rate of predation and removal by secondary dispersers of seeds deposited in primate feces. Studies such as that by Zhang & Wang (1995) suggest that these results should not be generalized. These authors showed that, although Ateles paniscus disperses about fifty times more Ziziphus cinnamomum seeds than Cebus apella, the survival probability of a seed dispersed by C. apella is 2.6 times greater.
They claim that the difference is due to the fact that C. apella defecates few seeds per fecal cake, increasing the survival rate of these seeds. The variability of seed dispersal patterns becomes increasingly evident as studies become more numerous and detailed (Garber & Lambert, 1998). The characteristics of the fruits and seeds can affect the dispersion pattern. Smaller seeds, for example, are more likely to be swallowed and defecated intact than larger ones (Lucas & Corlett, 1998; Norconk et al., 1998). The same primate species can prey on or disperse seeds of the same plant species at different times, depending on the general availability of food resources at the time (Gautier-Hion et al., 1993; Kaplin et al., 1998).