DUNG BEETLES AS SECONDARY SEED DISPERSERS - IMPACT ON SEED PREDATION AND GERMINATION

Dispersal of seeds away from the parent plant may facilitate escape fr om density-dependent seed mortality. However, many post-dispersal even ts can have a profound influence on the survival of dispersed seeds. B y incorporating seeds in the dung that dung beetles process for consum ption and oviposition, dung beetles could enhance seed survival if the y remove seeds from areas of high predation risk and place them in loc ations that avoid subsequent predation and that are suitable for germi nation. The role of dung beetles in seed survival was investigated ove r 15 mo in Kibale National Park, Uganda. Depths of seeds buried by bee tles, levels of predation on buried and unburied seeds, and germinatio n success of seeds buried to different depths were examined. Results s uggest that by burying seeds dung beetles increase the probability tha t seeds will escape predation and germinate. Of seeds placed in dungpi les, 69% remained at the surface, while 25% were buried from 1-3 cm in depth. Larger seeds were buried more shallowly than smaller seeds. Bu ried seeds were less likely to be removed by predators than seeds at t he surface. Germination of seeds buried at 1- and 3-cm depths was sign ificantly higher than seeds buried at 10 cm. For the species tested, m any seeds were buried by dung beetles between 1 and 3 cm and at this d epth there was a high probability of escaping predators and germinatin g. This demonstrates the potential ecological importance of dung beetl es in facilitating seed survival and provides data to consider the rol e of dung beetles in the evolution of seed attributes.