Deadly Toxic yeasts secrete proteins that are toxic to other yeasts. The P.I.s interested in evaluating the role of toxic yeasts in the organization of natural communities of yeasts species. The investigators past work has shown that these yeasts are relatively common in nature with at least one species present in all communities examined (i.e. the distinct yeasts communities associated with stem necroses of various cacti, slime fluxes of trees and decaying tissue of fruits). The P.I.'s will investigate two different yeasts, Pichia Kluyveri and P. thermotolerans, that occur in rotting fruits and decaying stems of cactus respectively. The system of Toxic P. Kluveri is especially interesting since it has a very flexible genetic system that displays species specific killing genotypes. In order to understand and link the knowledge on both the genetics and ecology the investigators will do an in depth ecological survey that assays genotypes of P. Kluyveri in conjunction with he resistance phenotypes of associated yeast species. This work, in parallel with detailed laboratory genetic analysis and field/laboratory experiments designed to reveal the adaptive significance of specific killer genotypes should allow the evaluation of the importance of toxin production to the organization of the community. The proposed work with P. thermotoloerans will provide comparative information from a relative different system; an system that is restricted terms of hosts (saguaro cactus) and geography (Sonoran Desert). The overall goal is to understand the fundamental reasons for community structure. Deadly toxins in yeasts represent an opportunity to study a case where the mechanism of interference competition is clear and unambiguous.
