Statistical Types of Selection

In complex creatures, the distribution of traits may be quite large make it much harder to discern the average from the individual.

Selection:

Some types of organisms within a population leave more offspring than others. Over time, the frequency of the more prolific type will increase. The difference in reproductive capability is called natural selection.

The most common action of natural selection is to remove unfit variants as they arise via mutation. In other words, natural selection usually prevents unfit genes from increasing in frequency.

Natural selection can be broken down into many components, of which survival is only one. Many other factors can also come into play. Overall, one can identify three major forms for population evolution:

Three examples of selection are shown before stabilizing, disruptive and directional. The black dots are individuals that die out before passing on their genes.

Stabilization: Removes the extreme ends of the distribution. Moves everything closer to the middle.

Directional: Depopulates preferentially one extreme side of the distribution (usually the disfavorable side)

Disruptive: Occurs when individuals at both ends of the curve have a higher survival probablity than those in the middle. Ultimately drives mutation and new, isolated species. Argueably this is what happens on Earth.

The Social Implications of Social Darwinsim in terms of stabilization, directional, and disruptive selection are about to become profound.