BIS 2C Chapter Notes - Chapter 21-4: Phylogenetic Tree, Atavism, Polyphyly
10 Aug 2018
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21. 1 all of life is connected through its evolutionary history. Phylogeny is the history of evolutionary relationships among organisms or their genes. Groups of evolutionarily related species are represented as branches in a phylogenetic tree. Named species and groups of species are called taxa. A taxon that consists of an ancestor and all of its evolutionary descendants is called a clade. Homologies are similar traits that have been inherited through a common ancestor. Synapomorphy: derived trait, shared by two or more taxa and is inherited from their common ancestor. Distantly related species may show similar traits that do not result from common ancestry. Convergent evolution and evolutionary reversals can give rise to such traits, which are called homoplasies. 21. 4 phylogeny is the basis of biological classification. Species is given a binomial, a genus then a species name. Only monophyletic groups are considered appropriate taxonomic units. Monophyletic: a group that consists of an ancestor and all of its descendants.
