Effects of seed aggregation on the removal rates of elaiosome-bearing Chelidonium majus and Viola odourata seeds carried by Formica polyctena ants

In a field dominated by Formica polyctena Foerst. ants, we examined the eff ect of seed aggregation on the seed-removal rates of two plant species: a l arge-seeded obligate myrmecochore Viola odorata L. and a small-seeded diplo chore Chelidonium majus L., which was autochorous as well as myrmecochorous . The effect was statistically non-significant in V. odorata but significan t in C. majus, with more closely aggregated seeds having higher removal rat es. The large seeds of the obligate myrmecochore were more quickly discover ed and repeatedly removed by ant workers than were the small seeds of the d iplochore.