Hide and seek: hidden genetic variance contributing to the adaptive potential of selfing populations

Standing genetic variation is considered a major contributor to the adaptive potential of species. The low heritable genetic variation observed in self-fertilising populations has led to the hypothesis that species with this particular mating system would be less likely to adapt. However, a non-negligible amount of cryptic genetic variation for polygenic traits, accumulated through negative linkage disequilibrium, could prove to be an important source of standing variation in self-fertilising species. Using a classical quantitative genetics model, we demonstrate that selfing populations are better able to store cryptic genetic variance than outcrossing populations, notably due to their lower recombination rate. Following a shift in the environment, this hidden diversity can be partially released, increasing the additive variance and adaptive potential of selfing populations. In such conditions, even though the process of adaptation itself is mating system dependant, selfers reach levels of fitness that are equal to or higher than outcrossing populations within a few generations. Outcrossing populations respond better to selection for the new optimum, but they maintain more genetic diversity resulting in a higher genetic load. In selfing populations, genetic diversity is remobilised, and new close-to-optimum genotypes are generated and quickly increase in frequency, leading to more homogenous populations. Our results bring new insights into the role of standing genetic variation for adaptation in selfing populations