Natural Selection

When no interfering variables are introduced, gene frequencies tend to remain steady from generation to generation. Mutations, migration, random genetic variation, and natural selection are all factors that disrupt the natural balance of gene frequencies. A mutation is a low-frequency shift in the frequencies of a gene that arises spontaneously in a population. When an individual transfers from one group to another and then interbreeds, there is a local change in gene frequency. Random genetic drift is a shift that occurs as a result of sheer chance from one generation to the next.

Natural selection reduces the disorganizing impacts of these events by increasing the frequency of favorable mutations across generations and eliminating unfavorable mutations, which have few or no offspring. Natural selection helps to preserve a group of creatures that are best adapted to their environment's physical and biological circumstances, and in some cases, it can even help them improve. Some traits, such as the tail of a male peacock, actually reduce an organism's chances of survival. Darwin proposed the hypothesis of "sexual selection" to explain such abnormalities.

In contrast to natural selection, sexual selection produces a structure that gives a competitive advantage in the search for partners.