The Refugial Debate

The refugial theory of biodiversity proposes that isolated locales (refugia) where animals and plants continued to exist during cold-stages of the Quaternary period resulted in the development of new species (speciation). In a Perspective, Willis explores evidence that supports the influence of refugia on speciation in temperate zones. However, it is becoming clear that speciation in the tropics cannot be attributed to refugia alone; other factors acting long before the Quaternary must have been involved.