Seed desiccation limits removal by ants

Abstract

Ants collect and disperse seeds that bear an attractive nutritive body called the elaiosome. In mesic habitats, many myrmecochorous plant species have elaiosomes that are usually soft and desiccation-sensitive. The aim of this study was to link the desiccation rate of two species of seeds (Chelidonium majus and Viola odorata) to the seed-removing behaviour of the ant Myrmica rubra. In laboratory experiments seeds of both species lost one-third of their weight in 24 h. Concurrently, seed removal rates decreased sharply (92%) for Viola odorata over 24 h and slowly for Chelidonium majus, which retained one-third of its attractiveness after one month of desiccation. Seeds recovered their initial weight almost entirely after being soaked in water for 18 h. This rehydration partially (Viola odorata) or totally (Chelidonium majus) restored the attractiveness of the seeds. In this paper, we show that the window of seed attractiveness during which ant–plant interactions occur is desiccation-dependent and plant-specific.