Islands closer to the mainland typically show:
“Higher immigration rates” for islands closer to the mainland typically show. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Island biogeography explains species richness as a dynamic balance between immigration and extinction. Immigration generally declines as an island fills with species, whereas extinction rises as more species divide finite area and maintain smaller populations. The remaining alternatives—“Lower immigration rates”, “Higher extinction rates”, “No change in immigration rates”—r
Ref: Biogeography, Lomolino et al., 5th Ed., Ch. 5-8