population ecology

Introduction
Genetic variation within local populations
- Effects of mode of reproduction: sexual and asexual
- Effects of population size
Population density and growth
- Life histories and the structure of populations
- Life tables and the rate of population growth
  - Survivorship curves
  - Calculating population growth
Regulation of populations
- Limits to population growth
  - Exponential and geometric population growth
  - Logistic population growth
- Population fluctuation
  - Factors affecting population fluctuation
  - Population cycles
- Species interactions and population growth
  - Interspecific interactions
  - Lotka-Volterra equations
- Metapopulations

References & Edit History Related Topics

Images

A herd of wildebeest, including calves, moves across a dusty savanna in Africa with scattered trees visible in the background.

Graph showing three survivorship curves: Type I (red, with human figures) has high survival early and drops steeply at old age; Type II (blue, with a bird) declines steadily; Type III (green, with a plant) drops sharply early, then levels off. X-axis is age, y-axis is number of survivors on a log scale.

Galapagos cactus finch (Geospiza scandens)

Side-by-side line graphs compare exponential and logistic population growth. The exponential growth graph shows a curve rising steeply upward, while the logistic growth graph shows an S-shaped curve leveling off at the carrying capacity of the environment.

A line graph with red and blue shaded areas shows cyclical rises and falls in the populations of snowshoe hares and lynx from 1855 to 1925, illustrating how hare population peaks are followed by lynx population peaks. Small illustrations of a running snowshoe hare and a lynx appear above the graph.

invasive prickly pear cactus in Australia

biological control of invasive prickly pear cactus in Australia

Quizzes

greylag. Flock of Greylag geese during their winter migration at Bosque del Apache National Refugee, New Mexico. greylag goose (Anser anser)

Biology Bonanza

Chutes d'Ekom - a waterfall on the Nkam river in the rainforest near Melong, in the western highlands of Cameroon in Africa.

Ecosystems

Related Questions

How can competition between two species lead to local extinction of one species?
How can predator-free areas affect prey population dynamics?
How can seasonal changes cause a population to fluctuate?
How did Alfred J. Lotka and Vito Volterra contribute to population ecology?
How did Konrad Lorenz and Nikolaas Tinbergen contribute to the study of animal behavior and populations?
How did Pierre-François Verhulst develop the logistic function?
How did Pierre-François Verhulst's view of population growth differ from Thomas Malthus's view?
How did improvements in medicine nutrition and public health reduce mortality in the United Kingdom?
How did the study of territorial nesting birds advance the understanding of population regulation?
How do age structure and sex ratio influence a population's fertility rate?
How do births and deaths change the size of a closed population?
How do closed populations differ from open populations in ecology?
How do density-dependent and density-independent factors work together to influence populations?
How do density-dependent factors affect population size?
How do ecologists define a population within a particular geographic area?
How do fertility and fecundity differ in population ecology?
How do immigration and emigration affect the size of an open population?
How do life tables help ecologists study animal and plant populations?
How do predation and disease help limit population growth?
How do predator-prey relationships create cycles in population size?
How do predators disease organisms and competitors limit the abundance of a species?
How do social customs and public health affect human population growth?
How do the Lotka-Volterra equations model competition between two species?
How do weather and climate influence population size regardless of population density?
How does a logistic growth curve differ from an exponential growth curve?
How does carrying capacity limit population growth?
How does competition cause population growth to level off near carrying capacity?
How does competition for food change as population density rises?
How does early reproduction affect the rate at which a population can grow?
How does migration affect human population growth compared with fertility and mortality?
How does mortality reduce the effects of density-dependent factors?
How does population density help ecologists study competition predation and disease?
How does population ecology differ from community ecology?
How does population ecology explain why some species are rare and others are abundant?
How does spring mixing in deep lakes lead to rapid plankton growth?
How is population growth rate calculated from births deaths immigration and emigration?
What does the maximum value in the logistic function represent for a population?
What does the midpoint of a logistic growth curve represent?
What happens during the three stages of logistic population growth?
Which environmental resources determine an environment's carrying capacity for a species?
Why are density-dependent factors sometimes called regulating factors?
Why are density-independent factors called limiting factors?
Why can competition for nesting sites increase in a dense bird population?
Why can low population density make it difficult for organisms to find mates?
Why did Thomas Malthus believe population growth could outpace food production?
Why did the Industrial Revolution contribute to faster population growth in the United Kingdom?
Why does disease spread more quickly in densely packed populations?
Why is the logistic growth curve shaped like an S?

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External Websites

Western Oregon University - Plant Population Ecology
University of Arkansas - Arkansas Forest Resources Center - Population Growth
McGraw-Hill Education - Ecology and Behavior
El Camino College - Population Ecology
Clemson University - The Basics of Population Dynamics
University of Washington - Population Ecology

Britannica Websites

Articles from Britannica Encyclopedias for elementary and high school students.

population biology - Student Encyclopedia (Ages 11 and up)

population ecology

Written by

John N. Thompson

Professor, Department of Ecology and Evolutionary Biology, and Director, STEPS Institute for Innovation in Environmental Research, University of California, Santa Cruz. Author of Interaction and Coevolution...

John N. ThompsonAll

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Britannica Editors

Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....

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History

population ecology, study of the processes that affect the distribution and abundance of animal and plant populations. A population is a subset of individuals of one species that occupies a particular geographic area and, in sexually reproducing species, interbreeds. The geographic boundaries of a population are easy to establish for some species but more difficult for others. For example, plants or animals occupying islands have a geographic range defined by the perimeter of the island....

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