Question of the Week

Biobasics Question of the Week:

What is Adaptive Radiation?

Biobasics Solution

Adaptive radiation is a process of evolution starting from a single point diversifying rapidly into different morphological adaptations. Phenotypes adapt in response to the environment, with new and useful traits arising. There are two basic causes of adaptive radiation: Innovation and Opportunity. (Source: en.wikipedia.org)

Innovation: The evolution of a novel feature may permit a clade to diversify by making new areas of morphospace accessible. A classic example is the evolution of a fourth cusp in the mammalian tooth. This trait permits a vast increase in the range of foodstuffs which can be utilized, with species able to specialize on feeding on a range of foodstuffs.

Opportunity: Adaptive radiations often occur as a result of an organism arising in an environment with unoccupied niches, such as a newly formed lake or isolated island chain. The colonizing population may diversify rapidly to take advantage of all possible niches.

Darwin's Finches are one of the best examples of Adaptive Radiation.
Adaptive radiations commonly follow mass extinctions: an extinction, many niches are left vacant. A classic example of this is the replacement of the non-avian dinosaurs with mammals at the end of the Cretaceous, and of Brachiopods by bivalves at the Permo-Triassic boundry.