Evolution

Change over time in heritable characteristics over generations in a population.

Change in a population’s alleles (variation).

Formation of new species over long periods of time.

Process where organisms better suited to their environment survive and reproduce more successfully.

An organism’s ability to survive and reproduce.

Environmental factors (predators, habitat, climate) that influence survival and reproduction.

Random changes in DNA that can change allele frequencies in a population.

A mutation that improves survival or reproduction and becomes more common over time.

Formation of a new species.

Group of organisms that can reproduce and create fertile offspring.

Barriers that prevent populations from reproducing with each other.

Species live in different habitats.

Physical reproductive structures do not fit together.

Physical barriers separate populations.

Species reproduce at different times (day/night or seasonally).

Barrier occurring after fertilization.

Incompatible chromosomes prevent normal offspring development.

Hybrid offspring cannot reproduce.

Hybrid offspring are weak or future generations become infertile.

Directional selection

Stabilizing selection

Disruptive selection

Change in allele frequency due to random chance This process can lead to significant changes in small populations.

Genetic drift occurring when a small group starts a new population This can result in reduced genetic variation.