BIOL 102 Lecture Notes - Lecture 11: Paraphyly, Cladistics, Polyphyly
14 Feb 2017
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Document Summary
Taxonomy is the scientific discipline concerned with classifying and naming organisms. The discipline of systematics classifies organisms and determines their evolutionary relationships. Phylogeny is the evolutionary history of a species or group of related species. A phylogenetic tree represents a hypothesis about evolutionary relationships. Each branch point represents the divergence of two species. Tree branches can be rotated around a branch point without changing the evolutionary relationships. Sister taxa are groups that share an immediate common ancestor. A rooted tree includes a branch to represent the last common ancestor of all taxa in the tree. A basal taxon diverges early in the history of a group and originates near the common ancestor of the group. A polytomy is a branch from which more than two groups emerge. What we can and cannot learn from phylogenetic trees. They show patterns of descent, not phenotypic similarity.
