9423416 Pierce Censuses of three separate populations in Amazonian Peru show striking association between the reproductive biology of the ant-plant, Cordia nodosa (Boraginaceae), and the species of ant inhabiting it. Cordia nodosa rarely produces flowers and fruits when inhabited by the most common symbiotic ant species, Allomerus demerarae, but regularly flowers and fruits when inhabited by three, rarer symbiotic ant species (Azteca spp., Myrmelachista sp.). Interestingly, there is no detectable difference in the rate of vegetative growth. These results indicate that Allomerus may be a parasite of C. nodosa. Moreover, colonization experiments show that parasitoid wasp predation on Azteca foundresses may in part mediate the coexistence of multiple ant species on the single resource represented by C. nodosa. These complex interactions make the C. nodosa-ant assemblage an ideal system in which to investigate factors shaping the evolution of mutualisms. This research will assess the relative costs and benefits provided by different ant associates to the plant, and will investigate the dynamics of colonization by C. nodosa. This research will address two important areas in community ecology: the role that parasitisms have in the evolution and ecology of mutualisms and the role that natural enemies have in maintaining species diversity. In doing so, this research will enhance understanding of mutualistic interactions and their role in ecological communities.
