GEOL 102 Lecture Notes - Lecture 9: Carl Linnaeus, Zoology, Botany
Document Summary
Taxon (plural=taxa)- a unit of biological diversity, also called a clade. Systematics- the study of biological diversity and its organization. Meant to reflect phylogeny, but based on morphology. Homology- morphology that is shared between groups because it was inherited from a common ancestor. Look at all the patterns of phylogeny suggested by morphology. The one that suggests that smallest number of convergence and reversal events is best. Monophyletic group- an ancestor and all its descendents. Sister taxa- two clades which share a common ancestor. Only monophyletic groups (clades) are natural taxa. The only natural boundaries to a clade are origination and extinction. Phylogenetic systematics base groups on the evolutionary process, not morphology. An ancestor and some, but not all, of its descendents. Cutoff is arbitrary and unnatural, so we avoid using these names too. A group that is not based on common ancestry. A mistake, so we definitely using these names.
