BIO SCI 94 Lecture Notes - Lecture 7: Cambrian Explosion, Ctenophora, Extinction Event

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Robin Bush

Document Summary

In this chapter you will learn that vast amounts of change have occurred in the. Two most compelling evolutionary events studied are: periods when species originate and diversify rapidly, periods when species go extinct rapidly. Adaptive radiation- when a single lineage rapidly produces many descendant species with wide range of adaptive forms. Cause dramatic changes to tree of life. Example: hawaiian silverswords: they are a monophyletic group, they speciated rapidly, they diversified ecologically. Two general mechanisms trigger adaptive radiations: new resources, new ways to exploit resources. Means the availability of new or novel types of resources. Has driven a wide array of adaptive radiations. Exa(cid:294)ple: a lizard s size a(cid:295)d shape correlates (cid:377)ith the habitat it occupies. Species that live on tree twigs have short legs and tail that allow them to move efficiently on narrow surfaces. Those that live in trees need long legs and tails.