BIOLOGY 1M03 Chapter 25: Tutuorial 2: Phylogenetic Trees and monophyletic groups
16 Oct 2018
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Node: where branches diverge into two or more sub-branches. Sister taxa: groups that occupy adjacent branches on a tree. Can be defined at any level or any node. Polytomy: multiple species appear to diverge at one node. Not enough data to tell the order of divergence. Out-group: this branch represents a taxon that diverged earlier from the other taxa in the tree; useful in determining the root of the tree. Monophyletic group / clade / taxon: ancestral species and all of its descendants. Can be defined by starting at any node on the tree and including all branches descending from that point. Synapomorphy: trait shared by two or more species inherited from common ancestor. Ancestral traits: describes a trait that was possessed by the common ancestor of the species on a branch of an evolutionary tree. Derived traits: traits that we do not believe were shared by a common ancestor.
