Answer:
A large island near the mainland
Step-by-step explanation:
A large island has a greater number of species, a greater interaction between them and a greater number of natural elements. All of this is capable of promoting biological specialization on a large scale, allowing new species to emerge more quickly than on a small island. Although a small island may also have great biodiversity, that island has fewer factors that promote the creation of new species, in addition to having fewer species interacting and creating new species.