Species turnover on islands is:
“Common and frequent” for species turnover on islands is. 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—“Rare and infrequent”, “Nonexistent”, “Always decreasing”—refer to different states, processes, or scales an
Ref: The Theory of Island Biogeography, MacArthur & Wilson, Ch. 2-4
