BOW-Natural selection and exaptation

BOW What is natural selection? How does it relate to mutations, genotypes and phenotypes? What is an exaptation.


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 is dependent on the existence of mutations in the genes coding for different characteristics of an organism. Most mutations in DNA are spontaneous and random, sometimes caused by passing cosmic rays or other exposure to radiation. Mutations may also be caused by errors in the formation of the genes in the parents' gametes in sexual organisms. Additionally, "proofreading" enzymes built into many higher organisms sometimes fail, leaving an incorrect version of an organism's DNA.

Furthermore, 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 is a feature that performs a function but that was not produced by natural selection for its current use. Perhaps the feature was produced by natural selection for a function other than the one it currently performs and was then co-opted for its current function. For example, feathers might have originally arisen in the context of selection for insulation, and only later were they co-opted for flight. In this case, the general form of feathers is an adaptation for insulation and an exaptation for flight. (http://evolution.berkeley.edu/evosite/evo101/IIIE5cExaptations.shtml)

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