Gillespie's Law is a principle in population genetics that describes how genetic drift affects small populations. It states that the rate of change in allele frequencies is inversely related to population size. This means that smaller populations experience more significant fluctuations in genetic traits over time compared to larger populations. The law highlights the importance of genetic diversity and the potential for inbreeding in small groups. As allele frequencies shift more dramatically, small populations may face increased risks of extinction due to reduced adaptability to environmental changes or diseases. Understanding this law is crucial for conservation efforts and managing endangered species.