Species can go through an adaptive radiation involving a diversification of that species , in response to having invaded a vacant ecological niche. It is thought the ability to do this, can be attributed to one or more key innovations developed by this species i. A radiating clade, which is the original ancestral species and descendants, then has opportune to exploit the new resources that often come with this new vacant niche. And perhaps not have to compete with other species present, for the same resources and space. The role of a key innovation in an adaptive radiation can be thought of as a new feature which increases ecological opportunity Schluter,
Adaptive radiation , evolution of an animal or plant group into a wide variety of types adapted to specialized modes of life. Adaptive radiations are best exemplified in closely related groups that have evolved in a relatively short time. A striking example is the radiation, beginning in the Paleogene Period beginning 66 million years ago , of basal mammalian stock into forms adapted to running, leaping, climbing, swimming , and flying. Many examples of speciation by adaptive radiation are found in archipelagoes removed from the mainland.
In evolutionary biology , adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches. The prototypical example of adaptive radiation is finch speciation on the Galapagos " Darwin's finches " , but examples are known from around the world. Four features can be used to identify an adaptive radiation: .
Please join StudyMode to read the full document. Evolution of Polar Bears The observed fossil transitions that inform our knowledge of Polar Bear speciation are very well documented. Bear fossils change through time: generally, when examining the fossil record, successively deeper levels of sediments or sedimentary rocks yield successively older fossils. For some transitions from one species to another, one can find a well-characterized series of transitional specimens leading the observer across the species "boundaries" Kurten, Sometime during the mid-Pleistocene period roughly , to , years ago , a number of brown same as grizzly bears Ursos arctos probably became isolated by glaciers.