Is the evolutionary passivity of sexual species always disadvantageous?
Evolutionary elasticity of sexual species could also be advantageous in a long-term perspective. Under fluctuating conditions of a stochastic environment, a plastic asexual species can adapt to a transient environmental change, while an elastic sexual species resists such change of its phenotype. When the environmental conditions return to normal, the plastic species can fail to return to its optimal phenotype quickly enough, and is therefore at risk of extinction, while the population of an elastic species is able to return to its original phenotype within a few generations. As was already suggested by G.C. Williams, the main advantage provided by sexual reproduction may consist in a substantial reduction in the evolutionary ability of most species. As a consequence of their elasticity, sexually reproducing species are evolutionarily passive throughout much of their existence and cannot opportunistically (i.e., without regard to future negative consequences) respond to temporary short-term changes in external conditions.