Consists of all the genes, including all the different alleles for each gene, that are present in a population

The number of times an allele occurs in a gene pool, compared to the total number of alleles in that pool for the same gene

A trait controlled by only one gene; eg: shells with or without bands on snails

Trait controlled by two or more genes; eg: height

When individuals at one end of the curve have higher frequencies than individuals in the middle or at the other end

When individuals near the center of the curve have higher fitness than individuals at either end

When individuals at the outer ends of the curve have higher fitness than individuals near the middle of the curve

In small populations, individuals that carry a particular allele may leave more descendants than other individuals leave, just by chance.
Over time, a series of chance occurrences can cause an allele to become more or less common in a population.

A change in allele frequency following a dramatic reduction in the size of a population

Allele frequencies change as a result of the migration of a small subgroup of a population

When a population is not evolving and allele frequencies in its gene pool do not change

Allele frequencies in a population should remain constant unless one or more factors cause those frequencies to change

Individuals select mates based on heritable traits, such as size, strength, or coloration

Population or group of populations whose members can interbreed and produce fertile offspring

Formation of a new species

Two populations that no longer interbreed

Two populations that are capable of interbreeding develop differences in courtship rituals or other behaviors

When two populations are separated by geographic barriers such as rivers, mountains, or bodies of water

When two or more species reproduce at different times

Comparing stretches of DNA to mark the passage of evolutionary time