Characterization of Mating Behavior in Natural Yeast Populations

• Main Authors: Jheng-Fen Guo, 郭正芬
• Other Authors: Jun-Yi Leu
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/81881186797583230528

碩士 === 國立陽明大學 === 生命科學系暨基因體科學研究所 === 100 === Reproductive isolation is one of the mechanisms of speciation which can be divided into two parts: pre-zygotic isolation and post-zygotic isolation. Pre-zygotic isolation is determined by geographic, ecologic, temporal, behavioral and mechanical factors, while post-zygotic isolation depends on their viability, fitness and fertility. In sexual organisms, mating behavior is a critical factor in reproductive isolation between different species. Hybrid incompatibility is also one of the main processes of speciation and acts as a reproductive isolation barrier. Reproductive isolation can also happen in the same species. According to the reinforcement model, once hybrid incompatibility has occurred between different populations, selection constrains the mating choice to reduce the intergroup mating between these populations. The intergroup mating can be costly in terms of their reproductive fitness. One of the possible causes of hybrid incompatibility is different ecological adaptation. Wild yeast populations that have been collected from different ecological niches may adapt to specific ecosystems. Such differences in adaptations can also lead to low fitness of individuals of a hybrid. In Saccharomyces cerevisiae, by selecting against intergroup mating, a previous study has shown that yeast cells could evolve with different mating speed and mating preferences. However, it is unclear whether such variation in mating behavior exists in natural yeast populations and understanding on the mating behaviors of the wild yeast populations is still limited. To study the pheromone signaling kinetics, we quantified the activation level of the signaling via GFP reporter and we found that the pheromone signaling kinetics distinctly varies between populations. To see if pheromone kinetics is correlated with mating speed, we further performed mating speed assays. We found that contrary to previous finding there is no significant correlation between mating speed and pheromone signaling kinetics of each strain. We also found that the mating choice exists between trains of two pheromone kinetics. Furthermore we will characterize the mating choice between and within pheromone kinetics patterns among wild trains to ascertain that the mating choice is contributed by the pheromone kinetics. In addition, using available whole genome sequences of these strains we plan to look for mating-related genes, which may contribute to their pheromone kinetics. we can establish if that mating choice is strong enough between populations and conclude that the yeast populations in the wild are in the incipient/early stage of speciation.