Bow 4 - Natural selection

                                                                    BOW 4 - Natural Selection

Natural selection is the gradual, nonrandom process by which biological traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution. Natural selection acts on the phenotype, or the observable characteristics of an organism, but the genetic (heritable) basis of any phenotype that gives a reproductive advantage will become more common in a population (see allele frequency). Over time, this process can result in populations that specialize for particular ecological niches and may eventually result in the emergence of new species. In other words, natural selection is an important process (though not the only process) by which evolution takes place within a population of organisms. As opposed to artificial selection, in which humans favor specific traits, in natural selection the environment acts as a sieve through which only certain variations can pass. Natural selection occurs through the mutation and recombination actions on the genome of the organism, whether through its plasmids or itself. Bare in mind that genotype, the combination of alleles of the genome, affects the phenotype, the physical appearance as a result of the genotype. Therefore, because natural selection initially occurs through the changes in the genome, natural selection acts on genotypes which may or may not have visible phenotypes. Exaptation, cooption, and preadaptation are related terms referring to shifts in the function of a trait during evolution.