BIO153H5 Final: BIO153-ExamNotes.docx
Document Summary
Chapter 27: phylogenies and 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. Section 27. 1 outline: tools for studying history: phylogenetic trees. A field guide to reading phylogenetic trees. 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. Adjacent branches are sister taxa (a taxon is any named group of organisms). 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. Tips are the tree"s endpoints and represent living groups or a group"s end in extinction.
