YEAST SUCCESSION IN THE AMAZON FRUIT PARAHANCORNIA-AMAPA AS RESOURCE PARTITIONING AMONG DROSOPHILA SPP

The succession of yeasts colonizing the fallen ripe amapa fruit, from Parahancornia. amapa, aas examined. The occupation of the substrate de pended on both the competitive interactions of yeast species, such as the production of killer toxins, and the selective dispersion by the d rosophilid guild of the amapa fruit. The yeast community associated wi th this Amazon fruit differed from those isolated from other fruits in the same forest. The physiological profile of these yeasts was mostly restricted to the assimilation of a few simple carbon sources, mainly L-sorbose, D-glycerol, DL-lactate, cellobiose, and salicin. Common fr uit-associated yeasts of the genera Kloeckera and Hanseniaspora, Candi da guilliermondii, and Candida krusei colonized fruits during the firs t three days after the fruit fell. These yeasts were dispersed and ser ved as food for the invader Drosophila malerkotliana. The resident fli es of the Drosophila willistoni group fed selectively on patches of ye asts colonizing fruits 3 to 10 days after the fruit fell. The killer t oxin-producing yeasts Pichia kluyveri var. kluyveri and Candida fructu s were probably involved in the exclusion of some species during the i ntermediate stages of fruit deterioration. An increase in pH, inhibiti ng toxin activity and the depletion of simple sugars, may have promote d an increase in yeast diversity in the later stages of decomposition. The yeast succession provided a patchy environment for the drosophili ds sharing this ephemeral substrate.