BI256 Lecture Notes - Lecture 2: Paraphyly, Polyphyly, Synapomorphy
Document Summary
Taxonomy and phylogeny of animals: biologists organize animals in a nested hierarchy of groups within groups according to evolutionary relationships as revealed by ordered patterns in their sharing of homologous features, darwin: theory of common descent or ancestry. To classify (systematize) animals according to their evolutionary relationships via an informative taxonomic system. Modern definition of species : thomas huxley (a contemporary of darwin) asked what is a species , no single species concept accepted by all zoologists. However, all agree: a species should constitute a population lineage with a history of evolutionary descent separate from other such lineages. Based upon sharing of derived characters (synapomorphies: clade groups consisting of a single organism and all its descendants relationship between taxonomic groups. Synapomorphy of fish, frog, lizard and monkey: 1. Monophyly: a monophyletic taxon includes the most recent common ancestor and all descendants of that ancestor: 2.
