Yeast communities as descriptors of habitat use by the Drosophila fasciola subgroup (repleta group) in Atlantic rain forests.

Abstract

Yeast communities associated with four species of the Drosophila fasciola subgroup (repleta group) in tropical rain forests were surveyed in an abandoned orchard, and rain forest sites of Rio de Janeiro and Ilha Grande, State of Rio de Janeiro, Brazil. Adult flies of Drosophila carolinae, Drosophila coroica, Drosophila fascioloides and Drosophila onca frequently carried Candida colliculosa, Geotrichum sp, Kloeckera apiculata and a Pichia membranaefaciens-like species. The most frequent yeasts in the crop of flies included Candida collicullosa, C. krusei, Pichia kluyveri and a P. membranaefaciens-like species. The physiological abilities and species composition of these yeast communities differed from those of other forest-inhabiting Drosophila. The narrow feeding niches of the fasciola subgroup suggested the use of only part of the substrates available to the flies as food in the forest environment, as noted previously for cactophilic Drosophila serido (mulleri subgroup of the repleta group) in a sand dune ecosystem. The cactophilic yeasts that were isolated have not been previously found in forests. The fasciola subgroup probably used epiphytic cactus substrates as breeding and feeding sites in the forest. The physiological profile of yeasts associated with the fasciola flies was broader than that of yeasts associated with the cactophilic Drosophila serido, suggesting that the fasciola subgroup represents an older lineage from which the South American repleta species evolved.