selection : Idioms & Phrases

noun a natural process resulting in the evolution of organisms best adapted to the environment
survival of the fittest; survival; selection.

(Biol.), a supposed operation of natural laws analogous, in its operation and results, to designed selection in breeding plants and animals, and resulting in the survival of the fittest. The theory of natural selection supposes that this has been brought about mainly by gradual changes of environment which have led to corresponding changes of structure, and that those forms which have become so modified as to be best adapted to the changed environment have tended to survive and leave similarly adapted descendants, while those less perfectly adapted have tended to die out though lack of fitness for the environment, thus resulting in the survival of the fittest. See Darwinism.

(Biol.), the selective preference of one sex for certain characteristics in the other, such as bright colors, musical notes, etc.; also, the selection which results from certain individuals of one sex having more opportunities of pairing with the other sex, on account of greater activity, strength, courage, etc.; applied likewise to that kind of evolution which results from such sexual preferences. Darwin.
In these cases, therefore, natural selection seems to have acted independently of sexual selection. A. R. Wallace.