Population size (N)

Definition

Population size (N) is the total number of individuals within a defined area at a given time. It is a fundamental parameter in population ecology used to understand population dynamics and health.

5 Must Know Facts For Your Next Test

1. Population size can fluctuate due to births, deaths, immigration, and emigration.
2. It is crucial for determining species conservation status and management plans.
3. Population size affects genetic diversity; smaller populations are more prone to genetic drift.
4. Ecologists often use sampling methods like mark-recapture or quadrat sampling to estimate N.
5. Carrying capacity (K) influences population size by limiting resources available for growth.

Review Questions

• What factors can cause changes in population size?
• Why is understanding population size important for conservation efforts?
• How do ecologists typically estimate the population size of a species?

Related terms

carrying capacity: The maximum number of individuals an environment can sustainably support.

genetic drift:

A mechanism of evolution that causes random changes in allele frequencies in small populations.

mark-recapture method: A technique used to estimate an animal population's size by capturing, marking, and releasing individuals.