Natural Selection and Phenotypic Variation

Mutations seem to be random, but long-term discussions on natural selection theory arise from the development of early structures and complex traits in organisms. These features are considered "pre-adaptive" as many of the complex adaptations observed in nature today are thought to arise from less complex adaptations where the function is simpler. In order to move from simple to complicated, it is necessary to have a transition phase in which both structures work simultaneously, or take over the new functions without disturbing the old functions.

Natural selection affects phenotypes and physical properties of organisms. The phenotype is determined by the genetic makeup (genotype) of the organism and the environment in which the organism resides. If different organisms in a population have different versions of genes for a particular trait, each of these versions is called an allele. It is this genetic variation that forms the basis for the phenotypic difference. One example is the ABO blood group antigen in humans, where three alleles control the phenotype.

Natural selection is the process of selecting organisms that better adapt to their environment to survive and breed more offspring. Natural selection chooses the phenotype or characteristic of the organism, giving the organism a reproductive advantage, making it a population pool of genes. In addition, mutations also occur in the genome of individual organisms, and descendants can inherit this mutation. This genetic variation makes it possible for more organisms to adapt to changing circumstances

By the combination of genetics and Darwin's mechanism in the 20th century, we were able to evaluate natural selection as a difference in survival and reproductive genotype, corresponding to a specific phenotype. Natural selection can only be applied to existing fluctuations in the population. This mutation is caused by a mutation, which is a change in some part of the trait's genetic code. Mutations are accidental and there are no potential advantages or disadvantages of premutation. In other words, there is change, so there is no change.

An important innovation in redefining genotype and phenotypic variation is that anthropologist C. Loring Brace suggests that this mutation is geographically or clonally scaled within the scope of natural selection, slow migration, or genetic drift As shown in Fig. For example, with regard to the color of the skin of Europe and Africa, Brace wrote as follows. So far the color of the skin has entered the Nile River from a southern tip of the Mediterranean Sea to the Nile River in Africa in a way that is undetectable. There is no hint of skin color boundary from end to end of the range, but the spectrum is from the brightest part of the northernmost world to the darkness which may be on the equator.