The Impact of Genetic Drift on Small Populations

Genetic drift refers to random changes in allele frequencies from one generation to the next, which occur due to chance rather than natural selection. In small populations, these random fluctuations are much more pronounced, leading to a faster loss of genetic variation compared to larger populations.

Calculating the Loss of Genetic Variation

The percentage of genetic variation lost per generation due to genetic drift in a population can be estimated using the formula:

Proportion of heterozygosity retained each generation=(1−12N)Proportion of heterozygosity retained each generation=(1−2N1)

Where $N$ is the population size.

• For a population of 50:

  1−12×50=1−0.01=0.991−2×501=1−0.01=0.99

  This means 99% of the genetic variation is retained, and 1% is lost each generation.

Why Does This Matter?

• Rapid Loss in Small Populations: The smaller the population, the greater the percentage of genetic variation lost each generation. For a population of 50, losing 1% of genetic variation per generation can quickly lead to reduced adaptability and increased risk of extinction.

• Conservation Implications: Understanding this rate is crucial for managing endangered species and maintaining genetic health in captive breeding programs.

Key Takeaways

• In a mammal population of 50 on an isolated island, approximately 1% (0.01) of its genetic variation is lost every generation due to genetic drift.

• This highlights the importance of maintaining larger population sizes to conserve genetic diversity and ensure long-term survival.

Correct answer:
(1) 0.01