Effect of environmental changes on the maintenance of biodiversity

Yeast has become over the last decade an excellent model system for environmental genomics studies of the molecular mechanisms underpinning adaptation and speciation (Ref 1 & 2). This project aims to understand the impact that environmental fluctuation have on species co-existance and therefore maintenance of biodiversity.

Evolutionary biologists since Darwin have struggled to understand how speciation happens and how sister species can coexist if they need to compete for the same resource. Why the best competitor does not eventually exclude all the others?

Environmental variability has a key role in promoting and maintaining diversity. Species strains might coexist in fluctuating environments because they respond differently to environmental conditions. We will use two natural yeasts adapted to grow at warm and cold temperature, respectively, as a study system (Ref 3). Saccharomyces cerevisiae and Saccharomyces kudriavzevii share the same natural niche but the first has an optimal growth at 37 °C while the second has an optimal growth at 22 °C. This difference in temperature preference allows them to co-exist in the same habitat.

Competition experiments involving growing different species under fluctuating temperatures and assessing the final population will be carried out. Genome profile studies, using BARseq technology on NGS Illumina platform, will be performed under fluctuating temperatures and in the presence of different carbon sources and nutrient limitations (Ref 3 and 4). Taken together, these results will help to explain at a molecular level how diversity originates and is maintained in nature. In addition, they will help us to understand how one important species adapts to a very common form of environmental variability.