ADAPTATIONS FOR A TWO-PHASE SEED DISPERSAL SYSTEM INVOLVING VERTEBRATES AND ANTS IN A HEMIEPIPHYTIC FIG (FICUS MICROCARPA: MORACEAE)

Figs (Ficus spp., Moraceae) are considered a classic example of plants with fleshy fruits adapted for seed dispersal by vertebrates, usually mammals or birds. Partially covering the endocarp of each individual drupelet of F. microcarpa is a fleshy, discrete lipid-containing exocarp that suggests adaptation for seed dispersal by ants. This structure is highly attractive to ants. F. microcarpa drupelets from which the fleshy exocarp was experimentally removed were much less likely to be transported by ants than those with this structure intact. The exocarps retained their attractiveness to ants and were not visibly altered following passage of the entire fruit through the gut of a frugivorous bird, the Indian Hill Mynah (Gracula religiosa). Germination percentage was not significantly affected by gut passage or exocarp removal. These results suggest that F. microcarpa has a two-stage seed dispersal system, in which primary dispersal by vertebrates is followed by secondary dispersal by ants. Dispersal aided by ants may be of significance in the biology of this exotic hemiepiphyte in southern Florida, where it is naturalized and appears to be spreading.