Generation

Definition

In population biology and life-history studies, a cohort of individuals produced by a single reproductive episode, or the interval between one reproductive episode and the next in a population. In univoltine species, one generation completes development annually; in multivoltine or polyvoltine species, multiple generations occur per year. The term also denotes the complete sequence of developmental stages from egg (or other propagule) through reproductive maturity in a single individual.

Etymology

Latin generatio, from generare 'to beget, produce'

Example

In the monarch butterfly (Danaus plexippus), the spring and summer populations in eastern North America represent successive overlapping generations, with the final autumn generation undergoing reproductive diapause and migrating to overwintering sites.

Synonyms

• cohort
• Brood

Related Terms

• Univoltine
• Bivoltine
• polyvoltine
• generation time
• cohort analysis
• Life cycle
• F1
• F2
• filial generation

Usage Notes

Distinguish from 'generation time' (the mean interval between birth of parents and birth of offspring). In laboratory genetics, F1, F2, etc., denote specific filial generations from controlled crosses. Field biologists may use 'generation' loosely for any discernible cohort, while demographers require stricter cohort definition. In some contexts, 'brood' emphasizes synchronous emergence rather than genetic lineage.