Explain why selection pressure can play a very conservative role in the evolution of a group. Explain the concept of "stabilizing selection."
In a sexually reproducing population, recombination has the tendency to disperse favorable gene combinations and to form less adaptively favorable combinations. Moreover, most mutations have the tendency to disrupt rather than strengthen favorable gene combinations. In contrast, selection has the tendency to eliminate these less favorable gene combinations and to preserve the favorable combinations, counteracting the disrupting effects of recombination and mutation. Thus, selection plays a conservative role in directing the evolution of a group. Selection against new, less favorable gene combinations is called stabilizing selection.
