Final answer:
The statement is false; linkage disequilibrium can be caused by genetic drift as well as by other processes like mutation, natural selection, and gene flow. Genetic drift leads to random changes in allele frequencies, especially in small populations.
Step-by-step explanation:
The statement that linkage disequilibrium is only created by genetic drift is false. While genetic drift can lead to linkage disequilibrium by chance alterations in allele frequencies, other mechanisms like mutation, natural selection, and gene flow can also contribute to the development of linkage disequilibrium. It's important to understand that genetic drift is one of several evolutionary processes that can affect the genetic makeup of a population.
Genetic drift is a random change in allele frequencies that occurs in small populations. This random fluctuation can lead to the elimination of alleles from the population, as seen in the provided examples where the frequency of an allele b is reduced purely by chance. Important to note is that genetic drift may happen more quickly in isolated populations, such as on an island as opposed to the mainland, because the small population sizes increase the impact of chance events.
Natural selection, on the other hand, is the differential survival and reproduction of individuals due to differences in phenotype. It can also cause alleles to become more or less common in a population. The founder effect and bottleneck effect are examples of events that can cause significant allele frequency shifts that are not attributable solely to genetic drift.