Asexual

Definition

Reproducing or developing without fusion of gametes or involvement of meiosis; occurring without sexual processes. In arthropods and other organisms, asexual reproduction includes parthenogenesis (development from unfertilized eggs), apomixis (asexual seed formation), fragmentation, and budding. Asexual reproduction typically produces offspring genetically identical or nearly identical to the parent, enabling rapid population growth in stable environments but limiting adaptive potential compared to sexual recombination.

Etymology

From Greek an- (without) + Latin sexualis (of sex), via English asexual, coined in 19th-century biology to contrast with sexual reproduction.

Example

Many aphid species reproduce asexually via parthenogenesis during spring and summer, with females giving birth to live, genetically identical daughters; sexual reproduction resumes in autumn to produce overwintering eggs.

Synonyms

• agamic
• parthenogenetic (when specifically by virgin birth)
• clonal (colloquial)

Related Terms

• Parthenogenesis
• apomixis
• Sexual reproduction
• cloning
• automixis
• thelytoky
• Arrhenotoky

Usage Notes

Distinguish asexual reproduction (biological process) from asexuality (sexual orientation in humans), which is outside this glossary's scope. In entomology, 'asexual' often specifically denotes thelytokous parthenogenesis (all-female lineages), as in some parasitoid wasps and stick insects. The term is sometimes used relatively: 'functionally asexual' describes lineages with extremely rare or vestigial sexual reproduction, such as certain bdelloid rotifers and some ostracods. Not all uniparental reproduction is truly asexual; automixis involves meiosis and can restore heterozygosity, blurring the sexual-asexual boundary.