BIOLOGY 1B Lecture Notes - Lecture 3: Synapomorphy, Paraphyly, Monophyly
Document Summary
Phylogeny - a genealogical history that connects all species on earth. Introduced during 19th century, from major thesis in darwin"s origin of species. Evolutionary process of descent with modification - when inherited traits gradually change from generation to generation making species evolve. Single species is considered when gene flow connects collections of populations. In time, can become isolated from one another. Prevents interbreeding, even if populations in same location again. Speciation occurs and produces two daughter species from one common ancestral species. Clades - groups of species depicted by these trees. Monophyletic groups - lineages that contain common ancestor and all of its descendants. Accurately reflect true evolutionary history of group of interest. Paraphyletic - group that includes ancestor and some but not all of its descendants. Polyphyletic - group that includes descendants from different ancestors, but not their common ancestor. Ex: birds are a monophyletic group of vertebrates.
