Random Drift and Small Populations | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Random Drift and Small Populations

• Population size refers to the number of breeding individuals in each population, which can range from large populations with hundreds or thousands of animals to small populations with tens of animals. The distinction between large and small populations varies among species.

• An initial random mating population can divide into numerous subpopulations due to geographical, ecological factors, or controlled breeding. The original population is termed the base population, while the subpopulations are referred to as lines. Together, all lines make up the entire population.

• Each line represents a small population where gene frequencies undergo dispersive processes. This dispersion is crucial in understanding the genetic makeup of these smaller groups.

• Estimating the current population size is relatively straightforward in theory but can be challenging in practice. The present genetic diversity is influenced by the population size in the past, making it complex to determine the historical population fluctuations.

• Random drift can significantly impact populations, especially in scenarios where founding members of a subpopulation are few. For instance, when a species colonizes a new area with a limited number of individuals, random drift can lead to substantial genetic variations.

• The size of a population is closely tied to fertility rates. High fertility rates result in rapid population growth, while low fertility rates lead to slower growth. Understanding these dynamics is essential in population studies.