Unit 7: Natural Selection and Artificial Selection

Natural Selection

A mechanism of evolution by which organisms with traits most suited to their environments survive and leave more offspring.

Variation

Differences that exist between individuals in a population, often due to genetics.

Overproduction and Competition

When more individuals are born than can survive due to limited resources, leading to competition.

Adaptation

Physical or behavioral traits that increase an organism's fitness in its environment.

Fitness

How well an organism can survive and reproduce in its environment.

Selection

The process by which individuals with greater fitness are more likely to survive and pass on their genes.

Stabilizing Selection

A type of selection that favors the average phenotype, making it more common over time.

Directional Selection

A type of selection that favors one extreme end of a phenotype spectrum, causing a shift in the curve.

Disruptive Selection

A form of selection that favors both extreme phenotypes and can lead to the evolution of distinct species.

Artificial Selection

The process by which humans breed organisms with desirable traits.

Intrasexual Selection

A type of sexual selection occurring between individuals of the same sex.

Intersexual Selection

A type of sexual selection occurring between individuals of opposite sexes.