The term "survival of the fittest: accurately characterizes Darwin's views on natural and sexual selection in that he proposed that in a struggle for survival, only those individuals best adapted to their environment would be most likely to survive, and reproduce, and so pass on their genes to another generation (About). By this process, the genes which had helped them survive would help the next generation survive. Those without such genes would not live to reproduce, or their offspring would not survive and so they would eventually die out. In this way the "fittest" survived. In sexual selection, the selection of a mate with these qualities would ensure the survival of the genes of the male of the species.
In this way, favorable or beneficial variations of traits are retained, and harmful or useless ones are lost from the gene pool (About). Across succeeding generations, different species thus undergo adaptations through the gradual accumulation of useful variations of traits which make them better able to survive and successfully reproduce in their particular environment. In this way, new species evolve through a series of many small and imperceptible steps. Darwin suggested that the breeding of domesticated animals was an artificial means of selection by which humans determined which animals would breed together so that they could control which favorable traits they wished to engendered in the offspring.
Darwin suggested that sexual selection did not always agree with his "survival of the fittest" notion of natural selection (About). Some species are attracted to their mates by virtue of features which are not at all necessary for survival in a particular environment and confer no enhanced survival capacity on their offspring. As an example, he cited the peacock, the male of which species has extremely elaborate tail plumage which confers no special survival advantage in its environment, but serves to attract fe...