BIOL208 Lecture 3: Systematics
29 Mar 2018
School
Department
Course
Professor
Document Summary
To construct phylogenetic hypotheses, systematists collect information about: anatomica physiological, or molecular features that make up organisms. In-group: the group of taxa whose relationships you are interested in determining. Out-group: one or more of the taxa that are related to the in-group, but that have diverged from it at an earlier time. Characters: are anatomical, physiological, or molecular features that make up organisms. Ex: type of structure, behaviour, dna sequence, etc. In simplest form character states are the presence/absence of a trait. Organisms with shared character states are likely to be more closely related than organisms with different character states. Character states in different species can be similar for one of two reasons: The character state was present in the common ancestor of the two groups and retained over time (shared ancestry). Characters that are similar because of descen from a common ancestor are said to be homologous.
