Daily Literature: 20 18-02-23

Considering that the same genus will be different in different contexts, there are many definitions about the concept of choice at present, which will lead to misunderstanding when reading the literature because of unclear concepts. The following are the definitions of several concepts that will appear in this article to avoid conceptual confusion when reading this article.

Some dictionary definitions of basic population genetics are already very clear. The traditional population genetic model that biology students first came into contact with was "A" representing alleles.

And "A" means that there is a choice when the fitness of the three possible genotypes (Aa, aa, AA) is different. When the fitness of three genotypes is different, or W (AA) >; w(Aa)gt； W(aa) or w (aa)

In the literature of molecular evolution, there are often positive selection, negative selection, purification selection and diversified selection. Here, these terms are defined as follows:

These choices basically increase population variation, but in recent molecular evolution literature, diversified selection is often used to describe those choices that improve variation. However, when an extreme phenotype of divergent selection is fixed in the population, divergent selection may reduce genetic variation, and other types will also increase genetic variation, so the so-called "generalized" diversified selection should be avoided.

When the new mutation does not affect the fitness of individuals (that is, W(AA)=W(Aa)=W(aa)), it is considered neutral. Usually, the neutral description of a website will not be affected by some selection conditions. The statistical method used to reject neutral evolution model is called neutral test.