Final answer:
Fixation is when an allele becomes the only one at its locus within a population, often due to genetic drift, which is more likely to occur in small, isolated populations or after events that sharply reduce population size.
Step-by-step explanation:
Fixation in genetics refers to the process by which a particular allele becomes the only allele at its genetic locus within a population, as a result of genetic drift or natural selection. Genetic drift is a mechanism of evolution that involves random fluctuations in the frequency of alleles from one generation to the next, particularly in small populations where chance events can have a large effect on the genetic makeup of the population.
Conditions that increase the likelihood of fixation due to genetic drift include small population size, isolation (such as on an island), and events that sharply reduce population size, like the bottleneck effect and the founder effect. A classic example of the founder effect includes the Afrikaner population, which due to a small number of founding colonists with specific mutations, now exhibits high incidences of certain genetic disorders.
To answer the review question, genetic drift would happen more quickly on an island as opposed to the mainland because island populations are typically smaller and more isolated, which are prime conditions for genetic drift to have a larger impact.