Final answer:
The probability of a given allele being drifted to fixation is equal to its initial frequency in the population. Genetic drift can lead to allele fixation or elimination, especially in small populations such as those found on islands.
Step-by-step explanation:
The probability of a given allele being drifted to fixation is equal to the frequency of that allele in the population at the start. For instance, if the initial frequency of allele a is 0.5 in the diploid population, the probability of this allele drifting to fixation (eventually reaching a frequency of 1) is also 0.5. The process of genetic drift is significant in small populations because alleles are sampled from a smaller gene pool, and random events can have a more pronounced effect on allele frequencies.
Genetic drift can lead to the elimination of an allele from a population by chance, as the alleles in an offspring generation are a random sample of the alleles in the parent generation. In scenarios where only a few individuals reproduce, alleles may be lost simply due to chance rather than natural selection. Over time, genetic drift can lead to one allele becoming fixed while another is lost, regardless of any selective advantage.
Imagine a population where genetic drift is occurring: if the allele b is present at a frequency of 0.3 (q = 0.3) and allele B at a frequency of 0.7 (p = 0.7), the probability that allele b will be lost is relatively high, especially after generations where individuals carrying allele b do not reproduce. In contrast, Hardy-Weinberg equilibrium describes a situation in which allele frequencies remain stable and are not affected by genetic drift.
Overall, genetic drift would likely happen more quickly on an island due to the typically smaller population size compared to the mainland, leading to greater fluctuations in allele frequencies.