Higher rates of sex evolve under K-selection

The geographical distribution of sexual and related asexual species has been suggested to correlate with habitat stability; sexual species tend to be in stable habitats (K-selection), whereas related asexual taxa tend to be in unstable habitats (r-selection). We test whether this broad-scale pattern can be re-created at a microevolutionary scale by experimentally evolving populations of facultatively sexual rotifers under different ecological conditions. Consistent with the pattern in nature, we find that the rate of sex evolves to lower levels in the r-selected than in K-selection environments. We consider several different explanations for these results.