Nearly all nectar-containing flowers are colonized by yeasts soon after flower maturation. This colonization is linked to pollinator visitation. The yeasts have been argued to affect nutritional quality of nectar, might produce volatiles or fermentation by-products that can attract or repulse pollinators and slightly increase flower temperature of winterblooming plants, which was argued to also affect pollinator behaviour.

The main questions of the project are:

• How do differences in between-flower versus within-flower community dynamics interlink to affect yeast species coexistence?
• Can trade-offs between yeast adaptations towards dispersal vectors and local competitiveness stabilize yeast metacommunities?

In addition to characterizing yeast communities in flowers of wild plants, trees and crops, we will quantitatively assess the role of mobile links (pollinators) on yeast community structure. It will be tested if there is a relationship between yeast diversity, plant diversity and pollinator diversity and if single yeast species depend on single pollinator species or pollinator groups for dispersal. Also the attractiveness of single yeast species on honey bees and wild bees will be tested. In the lab, we will perform competition experiments between selected yeast species to collect data on relative competitiveness and coalescence effects. Finally we will formulate a mechanistic model of expected meta-community dynamics and test this against community structures assessed in the AgroScapeLab-Quillow.