Two populations of deer, one of them large and living in a mainland forest and the other small and inhabiting a forest on an island, regularly exchange members that migrate across a land bridge that connects the island to the mainland. An earthquake destroys the bridge between the island and the mainland, making migration impossible for the deer. What do you expect will happen to allele frequencies in the two populations over the following 10 generations?

Key Concepts

Genetic Drift

Genetic drift refers to the random fluctuations in allele frequencies within a population, particularly in small populations. When the land bridge is destroyed, the island population becomes isolated, leading to genetic drift as it can no longer exchange alleles with the mainland population. Over generations, this can result in significant changes in allele frequencies due to chance events, especially in the smaller island population.

Gene Flow

Gene flow is the transfer of genetic material between populations through migration and interbreeding. In this scenario, the destruction of the land bridge halts gene flow between the mainland and island deer populations. This isolation can lead to divergent evolution, as each population adapts to its specific environment without the influence of the other, potentially resulting in distinct genetic traits over time.

Natural Selection

Natural selection is the process by which certain traits become more or less common in a population due to their impact on survival and reproduction. With the populations isolated, different environmental pressures may lead to different selective advantages in the mainland and island populations. Over generations, this can cause allele frequencies to shift as advantageous traits become more prevalent in each population, further enhancing their divergence.