KINE 2011 Study Guide - Midterm Guide: Synapomorphy, Genetic Distance, Polytomy
22 Oct 2017
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Lo e2: evolutionary history of a group of organisms is called its phylogeny. A phylogenetic tree/ cladogram shows the ancestor- descendent relationships among populations or species and clarifies who is related to who. A branch represents a populatio(cid:374) through ti(cid:373)e. a lo(cid:374)g (cid:271)ra(cid:374)(cid:272)h does(cid:374)"t (cid:373)ea(cid:374) (cid:374)o (cid:272)ha(cid:374)ge. A node/ fork is where two branches diverge- it represents speciation, the point in time when an ancestral species split into two or more descendent species. Nodes represent the common ancestor of the new diverging species. If more than two descendent groups emerge from a node, the node is called a polytomy. A tip/ terminal node is the endpoint of a branch, represents a group that is living today or went extinct. Tips connected by a single node on a tree are called sister taxa. Outgroup: a taxonomic group that is known to have diverged prior to the rest of the taxa. Read phylogenetic trees from the top to the bottom.
