gametic disequilibrium
Nonrandom association of alleles at different loci within a population. Also known as linkage disequilibrium.

gametic equilibrium
Random association of alleles at different loci within a population. Also known as linkage equilibrium.

gametogenesis
The creation of gametes through meiosis.

gene
A segment of DNA whose nucleotide sequence codes for protein or RNA, or regulates other genes.

gene drop
Simulation of the transmission of alleles in a pedigree. Each founder is assigned two unique alleles, and the alleles are then passed on from parent to offspring, with each offspring receiving one allele chosen at random from each parent (modeling Mendelian segregation), until all individuals in the pedigree have an assigned genotype.

gene flow
Exchange of genetic information between demes through migration.

gene genealogies
The tracing of the inherited history of the genes in an individual. Gene genealogies are most easily constructed using nonrecombining DNA such as mtDNA or the mammalian Y chromosome.

genet
A genetically unique individual.

genetic assimilation
A process in which phenotypically plastic characters that were originally “acquired” become converted into inherited characters by natural selection. This term also has been applied to the situation in which hybrids are fertile and displace one or both parental taxa through the production of hybrid swarms (i.e., genomic extinction).

genetic distance matrix
A pairwise matrix composed of differentiation between population (or individual) pairs that is calculated using a measure of genetic divergence such as FST.

genetic divergence
The evolutionary change in allele frequencies between reproductively isolation populations.

genetic draft
A stochastic process in which selective substitutions at one locus will reduce genetic diversity at neutral linked loci through hitchhiking.

genetic drift
Random changes in allele frequencies in populations between generations due to binomial sampling of genes during meiosis. Genetic drift is more pronounced in small populations.

genetic engineering
A process in which an organism’s genes are selectively modified, often through splicing DNA fragments from different chromosomes or species, to achieve a desired result.

genetic exchange
See gene flow.

genetic load
The decrease in the average fitness of individuals in a population due to deleterious genes or heterozygous advantage.

genetic rescue
The recovery in the average fitness of individuals through increased gene flow into small populations, typically following a fitness reduction due to inbreeding depression.

genetic stochasticity
Random changes in the genetic characteristics of populations through genetic drift and binomial sampling of alleles during Mendelian segregation.

genetic swamping
The loss of locally adapted alleles or genotypes caused by constant immigration and gene flow.

genetics
The study of how genes are transmitted from one generation to the next and how those genes affect the phenotypes of the progeny.

genomic extinction
The situation in which hybrids are fertile and displace one or both parental taxa through the production of hybrid swarms so that the parental genomes no longer exist even though the parental alleles are still present.

genomic ratchet
A process where hybridization producing fertile offspring will result in a hybrid swarm over time, even in the presence of outbreeding depression and with relatively few hybrids per generation.

genomics
The study of the structure or function of large numbers of genes in a genome.

genotype
An organism’s genetic composition.

gynodioecy
The occurrence of female and hermaphroditic individuals in a population of plants.