What does heterozygosity mean?
Heterozygosity is the genetic condition of having two different alleles at corresponding positions on homologous chromosomes. It describes variation at a particular gene locus and may also be used to indicate the overall level of such variation in a population. The term is especially common in genetics, evolutionary biology, ecology, and conservation biology, where researchers examine its relationship with adaptation, reproductive success, disease, and the genetic structure of populations. Heterozygosity is not identical to genetic diversity in general: it concerns differences between alleles at corresponding loci, whereas genetic diversity can also include variation across genes, chromosomes, and individuals. Its contrasting term, homozygosity, refers to the presence of identical alleles at corresponding loci. Although technical, heterozygosity is useful because it gives a precise name to one central form of inherited genetic variation.
nounThe state of having two different alleles at corresponding positions on homologous chromosomes. It can also refer to the amount of such genetic variation within a population.
- The condition of an organism or cell possessing two different alleles at corresponding positions on homologous chromosomes.
"The researchers measured heterozygosity across several gene loci in the population."
"Heterozygosity was highest among the populations sampled from the more diverse breeding grounds."
"The laboratory screened the population for heterozygosity at three gene loci."
The plural is used when referring to heterozygosity measured at multiple loci or in multiple populations.
"The study compared heterozygosities at several genetic loci."
Heterozygosity is the genetic shorthand for “same gene locus, different alleles”—a molecular source of inherited variation.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does heterozygosity come from?
Heterozygosity is an English scientific formation combining hetero-, meaning “different,” with zygosity, a term associated with Greek zygōsis, “a joining.” It belongs to the same Greek-derived family as zygote and zygotic, while homozygosity uses the contrasting prefix homo-, meaning “same,” with the same base. The terminology developed as modern genetics developed precise names for inherited patterns of variation.
Related word forms
How heterozygosity is actually used
This is primarily a formal scientific term used in genetics, evolutionary biology, and population biology. In general writing, “genetic diversity” may be more accessible when the broader concept is intended.
Easily confused with heterozygosity
Heterozygosity means carrying different alleles at corresponding gene loci, whereas homozygosity means carrying the same allele at those loci.
Heterogeneity means general lack of uniformity, while heterozygosity specifically refers to inherited variation involving different alleles.