Population cycles: generalities, exceptions and remaining mysteries.

Area of Science:

• Ecology
• Population Dynamics

Background:

• Population cycles are a persistent enigma in ecology.
• Numerous studies have investigated cyclic dynamics in diverse species such as snowshoe hares, voles, lemmings, forest Lepidoptera, and grouse.

Purpose of the Study:

• To explore the underlying mechanisms driving population cycles across different species.
• To identify common characteristics and factors contributing to population dynamics.

Main Methods:

• Review of existing literature on population cycles.
• Comparison of cyclic and non-cyclic populations.
• Analysis of experimental studies aimed at altering population dynamics.

Main Results:

• Cyclic species share traits like high reproductive rates and density-dependent mortality.
• Other common characteristics include transgenerational effects on reproduction and dispersal at peak densities.
• Genetic similarity among populations is also observed.

Conclusions:

• Both reproductive and mortality factors must be considered to understand population cycles.
• The precise drivers of variation in the amplitude and periodicity of population outbreaks are still unknown.