Explain the 3 graphs about the pattern of natural selection on polygenic traits.

Directional selection, stabilizing selection and disruptive selection are three types of natural selection

Directional selection

In population genetics, directional selection, or positive selection is a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype

stabilizing selection

Stabilizing selection is a type of natural selection in which the population mean stabilizes on a particular non-extreme trait value. This is thought to be the most common mechanism of action for natural selection because most traits do not appear to change drastically over time

disruptive selection

Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.

the trilobite is used as an index fossil for various geologic time periods as specific types of the trilobites were present in different geological time periods. they are a group of marine arthropods belonging to the class of trilobita.

explanation:

the tricuspid valve is present between right atrium and right ventricle