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population fluctuation
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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.
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population fluctuation

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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.
population cycles Cyclical fluctuations in the population density of the snowshoe hare and its effect on the population of its predator, the lynx. The graph is based on data derived from the records of the Hudson's Bay Company.

Population fluctuation refers to the natural variations in the number, abundance, or density of a species over time. These fluctuations are common and rarely follow a smooth growth pattern. Some populations exhibit regular cycles of increase and decrease, while others experience unpredictable, dramatic surges followed by rapid crashes.

Factors influencing these changes are broadly categorized as density-dependent or density-independent. Density-independent factors, such as weather and climate, affect populations regardless of their size. Density-dependent factors, like competition for resources or disease spread, intensify as population density increases. The interplay of these factors shapes population dynamics. For example, the populations of snowshoe hares and Canadian lynx are known to fluctuate in regular cycles, though the exact causes are still debated.123

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5 Britannica Sources
  1. population ecology - Factors affecting population fluctuation
  2. population ecology - Lotka-Volterra equations
  3. population ecology - Population cycles
  4. density-dependent factor
  5. density-independent factor

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