Systematics Ch10text book notes

Evolutionary classification
Criteria
1.genealogy/common descent
2.different degrees of modification which descendants have undergone.

Steps
1.sort into provisional classification by overall similarity.
2.test for monophyly, usually by cladistic analysis.

Recognition of taxa
1. Distinctness(size of gap)
2. Degree of difference(more charactors better)
3. Evolutionary role
4. Grade characteristics (groups of animals similar in general level of organization as distinct from groups of common genetic origin are called grades.)
5. Size of taxon
6. Equivalence of ranking in related taxa(balance)
7. Stability