BIO153H5 Final: BIO153 Exam Notes
Document Summary
Chapter 27: phylogenies and the history of life. Phylogenies and the fossil record are the major tools that biologists use to study the history of life. The cambrian explosion was the rapid morphological and ecological diversification of animals that occurred during the cambrian period. Adaptive radiations are a major pattern in the history of life. They are instances of rapid diversification associated with new ecological opportunities and new morphological innovations: mass extinctions have occurred repeatedly throughout the history of life. They rapidly eliminate most of the species alive in a more or less random manner. The evolutionary history of a group of organisms is called a phylogeny. A phylogenetic tree shows ancestor descendant relationships among populations or species. Figure 27. 1 shows the parts of a phylogenetic tree. Nodes occur where an ancestral group split into two or more descendant groups. A polytomy is a node where more than two descendant groups branch off.
