Population dynamics

Population dynamics is the branch of life sciences that studies the size and age composition of populations as dynamical systems, and the biological and environmental processes driving them (such as birth and death rates, and by immigration and emigration). Example scenarios are ageing populations, population growth, or population decline.

Overview

The study of population dynamics involves the use of mathematical models to make predictions about how a population will change. These models can be linear or non-linear. Non-linear models can include feedbacks, which can result in complex behaviours including chaos. Linear models do not include feedbacks and have a simple, direct relationship between the variables.

Factors influencing population dynamics

There are several factors that can influence the dynamics of a population. These include:

• Birth rate: The number of births in a population over a certain period of time. This is often expressed as a ratio to the total population.
• Death rate: The number of deaths in a population over a certain period of time. Like the birth rate, this is often expressed as a ratio to the total population.
• Immigration and emigration: The movement of individuals into (immigration) and out of (emigration) a population can have a significant effect on population dynamics.
• Carrying capacity: This is the maximum population size that can be supported by the available resources in the environment.
• Predation: The effect of predators on a population can significantly influence its size and growth rate.
• Disease: Disease can have a significant impact on population dynamics, particularly if it results in high mortality rates.

Mathematical models

There are several mathematical models used in the study of population dynamics. These include:

• Exponential growth model: This model assumes that the population grows at a rate proportional to its size.
• Logistic growth model': This model takes into account the carrying capacity of the environment and assumes that population growth slows as it approaches this limit.
• Lotka-Volterra equations: These equations model the dynamics of biological systems in which two species interact, one as a predator and the other as prey.

See also

• Demography
• Population ecology
• Population genetics
• Population health
• Population momentum
• Population pyramid

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