Deciphering genetic determinants of sexual mating in yeast and its effects on offspring fitness and evolution

Sexual reproduction is wide-spread in nature, allowing combination of beneficial alleles. Many papers show that species choose mating partners, possibly to optimize offspring fitness. Major questions in the field are how organisms choose their partners, and how is offspring fitness relates to that of its parents’. Using a collection of 1000 natural isolates of S. cerevisiae strains (Peter et al. Nature 2018) we have generated and mined massive data on mate choice and fitness inheritance, in unprecedented magnitude, using sexual mating.

In our experiments, all yeast strains were allowed to mate with one another while progenies were detected using barcode recombination system (Yachie et al. MSB 2016) and next generation sequencing. This method allows the detection of mate choice as well as the fitness of parents and progenies by competing all strains in a test tube.

While in fermentable carbon source, offspring fitness was mainly dependent upon parents’ fitness, in non-fermentable carbon offspring fitness increased with parents’ genetic distance. In addition, we have looked upon mating efficiency and found the it declines with parental mating efficiency in both carbon sources. As for mate choice, en masse experiments suggest that yeast choose mating partners, possibly to avoid low fitness offspring.

Together our finding suggests that mate choice is exercised in low eukaryotes such as yeast and it contributes to fitness inheritance and evolution.