Final answer:
Genetic drift in a population leads to a decrease in heterozygosity over time. This means that the frequency of heterozygotes decreases, while the frequency of homozygotes increases. Random chance events can cause genetic drift, resulting in the loss of alleles and reduced genetic variation within a population.
Step-by-step explanation:
Genetic drift refers to the random changes in the gene frequency of a population due to chance events rather than natural selection. In a population undergoing genetic drift, heterozygosity tends to decrease over time. This means that the frequency of heterozygotes (individuals with two different alleles) decreases, while the frequency of homozygotes (individuals with two identical alleles) increases.
For example, let's consider a population of rabbits with two coat color alleles, B (brown) and b (white). In the initial generation, the two alleles occur with equal frequency. However, due to random events, some rabbits will have more offspring than others, causing a shift in gene frequencies. Over time, this can lead to the loss of one allele (b) from the population. In subsequent generations, the population becomes increasingly homozygous for the remaining allele (B), resulting in a decrease in heterozygosity.
Overall, genetic drift tends to reduce genetic variation within a population and can have significant effects on the long-term evolutionary trajectory of a species.