Heterogeneity of the yeast flora in the breeding sites of cactophilic Drosophila

Abstract

of the yeast flora inthe breeding sites of cactophilic Drosophila. Can. J. Microbiol. 29: 6-14. Yeasts were isolated from 278 rots in cladodes and basal stems of Opuntia stricta sampled over 15 months at one locality. The most common yeast species among 370 nonidentical isolates representing 20 species were Candida sonorensis (27% of isolates) and Pichia cactophila (24%). These species generally were present in all months and throughout the area sampled. Other relatively common species (3-9% of all isolates) had much more restricted distributions in both time and space. The mean number of yeast species per rot was 1.27 k 0.082. and no yeasts were isolated from 20% of the rots sampled. Significant differences among months or seasons in average number of yeast species per rot were due primarily to lower numbers in the summer and winter months, while differences among rot types resulted mainly from a higher number in the longer persisting basal stem rots. Both hierarchical diversity analysis and analysis of the distributions of the 10 most common yeast species showed temporal effects (month or season) to be the major component contributing to heterogeneity, while microgeographic effects and rot type also were significant. The seasonal and microgeographic heterogeneity are interpreted in terms of longer persisting rots in part of the locality providing a reservoir for yeast species through the winter and are discussed in relation to the maintenance of genetic variation in cactophilic Drosophila that utilize the rots as feeding and breeding sites.

Pichia antillensis, a New Species of Yeast Associated with Necrotic Stems of Cactus in the Lesser Antilles

“…opuntiae var. opuntiae has been found only in necrotic tissues of Australian opuntias (1,14), the exact origin of which is not known in detail (7), although it is known that they were imported from the Americas into Australia within the last 200 years (1, 7). Extensive sampling of Opuntia species in Arizona and Texas (12), as well as on a number of islands in the Caribbean Sea (Starmer and Phaff, unpublished data), including those on which we discovered P .…”

Genotype-specific habitat selection for oviposition sites in the cactophilic species Drosophila buzzatii

“…The isofemale line experiments specifically simulate oviposition site preferences within rots. Natural rots contain one to five yeast species (Barker et at., 1983(Barker et at., , 1984 but the yeast species distribution within rots is patchy (Barker et at., 1987 The results of the isofemale line experiments support and extend those of Barker (1992), where females were given a choice of five yeast species including those used here. In those experiments, significant genetic variation was detected and the heritabii- proportions of eggs laid on yeast i vs. the other four) were generally not significantly different from zero for Candida sonorensis and CL opuntiae but were significant and ranged up to about 10 per cent for P. cactophi/a, Cr.…”

Pichia barkeri, a New Yeast Species Occurring in Necrotic Tissue of Opuntia stricta

“…The techniques used for yeast isolation and purification have been described previously (1,2,11,12). The locations and isolation sources of P. barkeri, P. kluyveri, and others are given in Table 1.…”

“…The rotting stems and cladodes of Opuntia species are specific habitats for a diversity of cactus-specific yeast species (1,2,7,11). During surveys of yeasts associated with rots of Opuntia species in Australia (1, 2), we isolated a number of strains that were initially identified by the system of Lodder (5) as Pichia kluyveri.…”