Tamarins and dung beetles: an efficient diplochorous dispersal system in the Peruvian Amazonia

anglais. peer reviewed

anglais. Dung beetles fulfil several key ecosystem functions but their role as secondary seed dispersers is probably one of the most complexes because several factors can diversely affect the seed / beetle interaction. Little is known about the dung beetle communities and their influence on occurrence and depth of burial of seeds dispersed in small faeces. The aim of this study was to investigate the effects of various factors (type of faeces, defecation pattern, season, habitat, seed characteristics) on dung beetle community (composition, number and size of individuals and species) and its consequences on occurrence and depth of burial of seeds primarily dispersed by two tamarin species. We captured dung beetles in a Peruvian rainforest with 299 dung-baited pitfall traps to characterize the dung beetle community. Seed burial occurrence and depth were assessed by marking, in situ, 551 dispersed seeds in faeces placed in a cage. We observed a significant effect of the amount of dung, season, time of defecation, and habitat on the number of individuals and species of dung beetles, as well as on seed burial occurrence and depth, while the type of faeces only significantly influenced the number and the size of dung beetles. Surprisingly, there was no significant effect of seed length, shape, and mass neither on seed burial occurrence, nor on burial depth. We highlighted that dung beetles compete for the first access to the resource on small faeces rather than for space for the building of their nest as observed on large faeces.