phylogeny and cladistics

• The evolutionary history of an organism is called its phylogenetic tree.
• the order of Linnaeus hierarchical classification system is: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
• taxonomy - discipline of naming and categorizing organisms, based on shared traits: morphological traits, developmental features/processes, molecular (e.g. gene/protein sequences)
• phylogeny is the evolutionary history of a species or related species; the evolutionary relationship can be seen as branching phylogenetic trees
• nodes (branch points) depict common ancestors
• discipline of systematics classifies organisms and determines their evolutionary relationships
• to infer evolutionary relationships systematists mostly use: fossils, morphological data, biochemical data (usually proteins), and genetic data
• each branch point represent the divergence of two species (speciation event)
• 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
• parsimony is based on the principle that the simplest explanation is usually correct
• outgroup is a more distantly related group of organisms that serves as a reference
• phenotypic and genetic similarities due to shared ancestry are called homologies
• homology is similarity due to shared ancestry
• analogy is similarity due to convergent evolution
• clades are groups of organisms descended from a single common ancestor
• cladistics groups organisms by common descent
• monophyletic consists of the ancestor species and all its descendants
• paraphyletic includes an ancestral group but not all of its descendents
• polyphyletic doesnt include the ancestral group or any of its descendants
• a shared ancestral character is a character that originated in an ancestor
• a shared derived character is character novel to a particular clade (not found in the ancestor)