Experimental evolution of mating discrimination in budding yeast.

Area of Science:

• Evolutionary Biology
• Genetics
• Microbiology

Background:

• Assortative mating, mating between similar phenotypes, is crucial for preventing gene flow during speciation.
• Reinforcement, the enhancement of assortative mating in allopatric groups upon secondary contact, prevents costly hybrid offspring.
• Previous studies in Drosophila suggest complex genetic architectures underlying mating discrimination evolution.

Purpose of the Study:

• To investigate the evolution of assortative mating and mating discrimination.
• To model the evolution of reproductive isolation using Saccharomyces cerevisiae.

Main Methods:

• Evolved mating discrimination in Saccharomyces cerevisiae populations over 36 selection cycles.
• Quantified mating preference by comparing mating rates between evolved and ancestral populations.
• Performed genetic analysis to identify mutations responsible for altered mating preferences.

Main Results:

• Evolved yeast populations exhibited a fivefold increase in mating discrimination compared to ancestors.
• Mating kinetics varied among evolved cultures, with some mating faster and others slower.
• Evidence of one-way gene flow persisted between selected and reference populations.
• Genetic analysis revealed accumulation of multiple mutations influencing mating preference.

Conclusions:

• Subtle changes in mating behavior can significantly impact the evolution of reproductive isolation.
• The study demonstrates that assortative mating can evolve through accumulated genetic changes.
• Saccharomyces cerevisiae serves as a tractable model for studying the evolution of mating behaviors and reproductive isolation.