DUAL FUNCTION OF THE ELAIOSOME OF CORYDALIS AUREA (FUMARIACEAE): ATTRACTION OF DISPERSAL AGENTS AND REPULSION OF PEROMYSCUS MANICULATUS,A SEED PREDATOR

It has been suggested that one of the selective advantages of ant dispersal is the burial of seeds in ant nests where predators such as small rodents cannot find them. The elaiosomes of Corydalis aurea (Fumariaceae) are extremely attractive to ants, which assiduously gather the seeds and take them to nests. However, seed production commonly exceeds the gathering capacity of ants so that seeds accumulate beneath the parent plants. In spite of this, no signs of rodent predation are evident. Experiments with a major seed predator, the deer mouse Peromyscus maniculatus, show that when given the choice of seeds with and without elaiosomes, the mice consume significantly more seeds without elaiosomes. This remains true whether or not the intact seeds bear fresh, moist elaiosomes or dry, withered ones. Our experiments strongly suggest that the elaiosome has a dual function, the attraction of the ant seed dispersers and the repulsion of seed predators.