Life cycle

Definition

The complete sequence of developmental stages through which an organism passes from the origin of a new individual (usually by reproduction) until that individual has in turn produced the next generation. In arthropods, the life cycle typically encompasses embryonic development, post-embryonic growth through successive instars, sexual maturation, and reproduction. The duration and complexity of life cycles vary enormously: some aphids complete the cycle in days via parthenogenesis, while periodical cicadas require 13–17 years. Life cycle structure—whether ametabolous (no metamorphosis), hemimetabolous (incomplete metamorphosis), or holometabolous (complete metamorphosis with pupal stage)—is a major axis of insect classification and ecological strategy.

Etymology

Example

The monarch butterfly (Danaus plexippus) has a multigenerational life cycle in which successive generations complete the annual migration from Mexico to Canada, with the final autumn generation entering reproductive diapause to survive the return journey.

Synonyms

• ontogeny
• developmental history

Related Terms

• instar
• Metamorphosis
• Diapause
• Univoltine
• Bivoltine
• multivoltine
• Semelparity
• iteroparity
• generation time

Usage Notes

Distinguish from 'life history,' which encompasses not only developmental stages but also survival schedules, fecundity schedules, and reproductive tactics. 'Life cycle' is sometimes used loosely for any repeating process; in entomology, reserve it for organismal development. Contrast with 'life span' (duration of individual life) and 'generation time' (interval between birth and reproduction of offspring). Specialists often specify 'annual life cycle' or 'pluri-annual life cycle' to clarify temporal scaling.