Definition
What is a population?
In biology, a population is a group of individuals of the same species that live in a particular area and can interact and breed with one another. It is the level of organization between the single organism and the community, which is made up of all the populations of different species in a place. Populations are dynamic: they grow and shrink through births, deaths and the movement of individuals in and out, and they change with the seasons, disasters and competition.
Ecologists describe a population by its size (the total number of individuals), its density (individuals per unit area or volume), its spatial pattern (clumped, random or evenly spaced) and its age structure. Counting every individual is rarely practical, so researchers sample, using quadrats for plants and slow-moving animals and mark-and-recapture for mobile ones. Life tables and survivorship curves show how the risk of dying changes with age.
The population is also the unit of evolution. Individuals do not evolve; instead, the frequencies of alleles in a population's shared gene pool shift over generations. In statistics, the word has a broader meaning: the whole group from which a sample is drawn.
Word parts
Where does the word “population” come from?
- popul-
- peopleLatin populus
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Related
Terms that go with it
- Carrying capacityCarrying capacity is the largest population of a species that an environment can sustain over time with the food, water and space available.
- Gene flowGene flow is the movement of alleles from one population into another when individuals or their gametes migrate and then breed.
- Genetic driftGenetic drift is a random change in allele frequencies from one generation to the next, caused by chance rather than by natural selection.
- Hardy–Weinberg equilibriumHardy–Weinberg equilibrium is the state in which allele and genotype frequencies in a population stay constant from one generation to the next.
- EcosystemAn ecosystem is a community of living organisms together with the nonliving environment they interact with, linked by energy flow and nutrient cycling.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Biology 2e, 45.1 Population Demography
- National Geographic Education: Population Density
- Wiktionary: population
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