Topic 2.3 — Evolution written portion maybe

What is natural selection?

Natural selection occurs when individuals with traits that increase fitness survive and reproduce more successfully than others.

What is stabilizing selection?

Stabilizing selection favors intermediate phenotypes and reduces variation around the average phenotype.

What is directional selection?

Directional selection favors one extreme phenotype and shifts the population average toward that extreme.

What is disruptive selection?

Disruptive selection favors both extreme phenotypes and selects against intermediate phenotypes.

How do you identify the optimal phenotype?

The optimal phenotype is the phenotype with the highest fitness, survival, or reproductive success.

What is mutation?

Mutation is a random change in DNA that creates new genetic variation within a population.

What is genetic drift?

Genetic drift is a random change in allele frequencies caused by chance events, especially in small populations.

What is a bottleneck effect?

A bottleneck effect occurs when a population is drastically reduced in size, causing loss of genetic diversity.

What is a founder effect?

A founder effect occurs when a small group establishes a new population with different allele frequencies than the original population.

What is gene flow?

Gene flow occurs when individuals move between populations and transfer alleles.

How does natural selection differ from genetic drift?

Natural selection is nonrandom and favors beneficial traits, whereas genetic drift changes allele frequencies by chance.

How can you tell if evolution was caused by natural selection?

Traits consistently change in a direction that improves fitness under specific environmental conditions.

How can you tell if evolution was caused by genetic drift?

Trait changes appear random and are often strongest in small populations.