BIOL359 Lecture Notes - Lecture 6: Molecular Phylogenetics, Phylogenetic Tree, Monophyly
11 Aug 2019
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Phylogeny is a hypothesis of ancestor descendant relationships. Phylogenetic tree is a graphical summary of a phylogeny. Phylogenetics is the study of ancestor descendent relationships. The objective of phylogeneticists is to construct phylogenies. All life forms are related by common ancestry and descent. The construction of phylogenies provides explanations of the diversity seen in the natural world. Phylogenies can be based on morphological data, physiological data, molecular data, or all three. Today, phylogenies are usually constructed using dna sequence data. A group that includes all of the descendants of a common ancestor is a monophyletic group or clade. A non-monophyletic group is any case that does not satisfy the above, such as: Paraphyletic: a group that includes some, but not all of the descendants of a common ancestor. Polyphyletic: assemblages of taxa that have been erroneously grouped together on the basis of homoplasious characters (e. g. , vultures which we will discuss in a later topic).
