Vocabulary

allele

an alternative version of a gene

allele frequency

the proportion of all alleles that are of a specified type

crossing-over

the exchange of DNA between homologous chromosomes during meiosis

gene flow

a change in the gene pool caused by individuals entering or leaving a population

gene pool

the total set of genes of all individuals in a population

genotype frequency

the proportion of individuals in a population that have a particular genotype

Hardy-Weinberg equilibrium

the state of a population in which allele and genotype frequencies do not change between generations because evolution is not occurring

heterozygous

having two different alleles for a gene

homozygous

having two identical alleles for a gene

independent assortment

the random distribution of the pairs of genes on different chromosomes to the gametes during meiosis

locus (plural, loci)

the physical location of a gene on a chromosome

macroevolution

evolutionary change at or above the species level

meiosis

a process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, resulting in the production of gametes

microevolution

a change in allele frequencies within a population from one generation to the next

mutation

a change in DNA sequence

natural selection

a mechanism of evolution in which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do

nonrandom mating

reproductive pairing in which mates are chosen based on attributes or opportunity, not random selection

nucleotide

an organic compound consisting of a sugar, a phosphate, and a nitrogenous base; this compound forms the basis of a genetic sequence

population

an interbreeding group of individuals of the same species