The impact of consumption of fruit by vertebrate and invertebrate frugivores on the germination success of an Australian rainforest seed

Abstract

The consumption of fruits by vertebrates and invertebrates can be both advantageous or detrimental to the survival of the seeds they contain. This study investigated the effect of fruit size and consumption of fruit pulp by rodents and beetles on the germination of the seeds of 'Acmena graveolens', a tropical rainforest canopy tree found in northern Australia. As fruit size increased, germination success and the amount of pulp remaining on the fruits was greater. When beetles were absent, germination success was highest when most of the pulp was removed by rodents, suggesting that they removed an inhibitor of germination. When beetles were present, germination success did not differ significantly across pulp categories, so beetles apparently enhanced germination in seeds with little pulp initially removed, possibly by further removal of fruit pulp. In this study, both rodents and beetles enhanced germination success of 'A. graveolens' seeds by consumption of fruit pulp. Acting as facilitators of germination is a relatively unusual role for both these frugivores that are generally considered to act as seed predators or (in the case of rodents) dispersers.