Is allopatric speciation more likely to occur on an island close to a mainland?

Yes, allopatric speciation is more likely to occur on an island close to a mainland because geographic isolation plays a key role in driving speciation. Isolation on an island can lead to reproductive barriers and genetic divergence, promoting the process of allopatric speciation. With limited gene flow from the mainland, unique evolutionary trajectories can lead to the formation of new species on the island.