Print PageMyrmecochory, or seed dispersal by ants, is the dispersal syndrome of thousands of plant species, and myrmecochorous plant species make up a large minority of plants in some habitats. Seeds of myrmecochorous plants have elaiosomes, which are fleshy appendages thought to have evolved as a nutritional reward for ants. Although the benefits of myrmecochory to plants are quite well studied, little is known about whether and how ants benefit from this partnership. We provisioned 50 laboratory colonies of the woodland ant Aphaenogaster cf. rudis with seeds of four sympatric understory herbs and tested whether eating elaiosomes yielded a measurable benefit to the ant colonies. We also investigated whether elaiosome quality varied among plant species and whether ants were more willing to disperse seeds offering higher quality elaiosomes as rewards.
Results/Conclusions
Compared to colonies fed only a standardized control diet, A. rudis colonies provisioned with seeds of some plant species were able to maintain larger clutches of brood, suggesting that the elaiosomes of these species provide an important nutrient to ants. For other plant species, we detected no such benefit. Additionally, foraging ants removed the seeds of some plant species faster and more frequently than others, which in the field would probably result in a greater benefit for the plant partner. However, the hierarchy of ant preference did not match that of ant colony performance, a pattern which may indicate a mismatch between the quality of elaiosomes as a reward and the signals in elaiosomes that attract ants.
