Research
Experimental Evolution and Genomic Analysis of Yeast Mating Preference and Genetic Buffering
An important question in biology is how cells evolve a new phenotype. Until recently, theoretical approaches to this question could only be tested indirectly by data collected from the field or by inferences made from interspecies comparisons. Experimental evolution (conducting evolution experiments in a controlled laboratory setting) offers a powerful way to understand mechanisms of adaptation because evolution can be followed directly and repeated experiments can ask whether there are general features underlying the selected adaptation. Although powerful in principle, these studies suffer from two difficulties, the selected traits have been limited in number and complexity, and it has been hard to map and characterize the mutations that confer the novel phenotype. To further understand the molecular or cellular bases of evolution, I have developed a system that overcomes these disadvantages and will use it to investigate two fundamental biological phenomena.
I. Experimental evolution and genomic analysis of mating preference
Evolving a new mating preference is a critical step of speciation that has been subjected to extensive theoretical analysis. I have evolved a new mating preference in the budding yeast S. cerevisae. Specifically, I will address the following questions.
- How do cells change their mating preference ?
- If there are multiple mechanisms to achieve mating bias (e.g. new pheromone and receptor, new mating type), are they equally feasible during evolution ?
- Once a strong mating preference is evolved, how stably can it be maintained ?
II. Experimental evolution and genomic analysis of genetic buffering
Genetic buffering is the mechanism that suppresses phenotypic variation under normal conditions and releases this variation when its function is compromised. Buffering systems have been suggested to play an important role in protecting developmental processes from environmental and genetic perturbations and in setting the tempo of evolution since they can moderate these perturbations or help a population accumulate genetic variations essential for selection. However, only very few genes have been shown to participate in buffering. To further understand the molecular basis of genetic buffering, I will use a systematic approach to evolve enhanced buffering systems and screen for novel buffering genes. Specifically, I will address the following questions.
- How much do buffering systems affect the rate of evolution and the fitness landscape ?
- Can genetic variations be buffered at different molecular levels (i.e. transcriptionally, posttranscriptionally, translationally, posttranslationally)? Are there common design principles for genetic buffering?
- Do different buffering mechanisms interact with each other? Can they be regulated?
