How sex pheromones diversify: Lessons from yeast

What happens to sex pheromones as new species emerge? New research studies sex pheromones in the fission yeast Schizosaccharomyces pombe, revealing an ‘asymmetric’ pheromone recognition system in which one pheromone operates extremely stringently whereas the other pheromone is free to undergo a certain degree of diversification, perhaps leading to a first step towards speciation.