Why does the ecology of asexual and sexual species differ?
The plasticity of asexually reproducing species should be better off in an environment, in habitats poor in resources or where the survival of most species is limited over a long period of time by unfavorable abiotic factors. Here, the main criterion of evolutionary success is how well (not how quickly) the species can change its phenotype in response to the requirements of the environment. It is noteworthy that asexually reproducing species or asexually reproducing lineages of otherwise sexually reproducing species of plants and animals are found primarily in habitats with extreme conditions – in habitats which are extremely dry, extremely cold or extremely poisonous. The proportion of asexual species increases, for example, with increasing altitude and latitude or in places where the soil contains high concentrations of toxic heavy metals. On the other hand, sexually reproducing (elastic) species should be better off in an environment rich in resources and with many competing species where the rate of evolutionary responses in the coevolutionary “arms race” plays the crucial role. The fact that they can retain most of their genetic polymorphism enables them to rapidly respond to any evolutionary pressure by shifting the frequencies of their alleles, without needing to wait for rare, advantageous mutations.