Phylogenetics

• Taxonomy : describing, naming, and classifying
• Phylogeny: evolutionary history
• Hierarchical classification levels: domain, kingdom, phylum, class, order family, genus, species
• Taxon: grouping of any organism at any one of the levels
• each level is more inclusive
• all species at a level share characteristics of that group
• Phylogeny: study of evolutionary history and the relationships among organisms, based in shared ancestory
• Unrooted tree: show relationships, but does not show ancestral roots
• rooted: one branch point that represents most recent CA of all taxa on tree
• Branch points= Nodes
• Dichtomies: divergence of 2 linages from a ca
• Extant species: currently living and at the tip of branches
• Basel taxon: 1st linage to diverge from CA of group
• outgroup= Basel taxon
• Ingroup= everything else
• sister taxa: organisms that share immediate CA, only sister taxa when 2 species are closely related
• polytomy: branch points with more than 2 descendent groups
• States: alternative forms of a character
• Character: defined attribute of a species
• the more 2 species are closely related the more they share, must result from common ancestry
• character states may be similar from two reasons: homologous and analogous
• Homologous: inherited from CA, look and function differently but underlying structure is the same
• Analogous: trait developed, not shared with common ancestor
• convergent evolution: when species evolve to have similar traits due to similar environmental pressures
• Cladistics: uses homlogies to classify organisms based on CA
• Clade: group which includes ancestral species and all of its decedents
• Three possible groups of clade: monophyletic, paraphyletic, polyphyletic
• Monophyetic: CA and all descendants
• paraphyletic group: CA and some of its descendants
• polyphleytic group: distantly related species and doesn't not include most recent CA
• acquiring trait first is shared derived trait
• acquiring trait second is ancestral trait
• Divergae: same ancestor, different function
• converge: different ancestor, same function