taxa(singular, taxon)
named groups of organisms
phylogeny
a diagram of evolutionary history that superficially resembles a cladogramhas an absolute time axisinstead of at the top, taxa are ordered vertically to indicate when they lived
phylogenetic systematics orcladistic analysis
Hennig's method for ascertaining genealogiesEach dichotomy marks the splitting and disappearance of an ancestral species and the formation of two daughter species
clade
monophyletic group(an ancestral species and all of its descendants)all of the taxa that possess a given synapomorphy, but not other taxa
cladogram
THIS IS AN HYPOTHESISa branching diagram where all of the taxa under study are listed at the top, with intersecting lines, or branches, beneath them to illustrate their common ancestry relationships
character states
a feature that is an observable part or attribute of an organism, in it's different forms or appearancescoded by assigning a number: 0, 1...
plesiomorphy
an "ancestral", "less specialized", or "primitive" character
apomorphy
a "derived", "specialized", or "advanced" character
outgroup comparison
a means of determining which character in a transformation series is a plesiomorphy and which is an apomorphy
outgroup
the plesiomorphic character statethe most closely related taxon to, but not the ancestor of, the set of taxa under study
ingroup
the taxon under study
synapomorphy
shared derived characteran apomorphy that occurs in two or more taxa
autapomorphy
an apomorphy that occurs in only one taxondemonstrate the uniqueness of taxa, but they don't help identify clades
paraphyletic group
consists of an ancestor and some of its descendantsan incomplete clade, defined by the absence of at least one character
polyphyletic groups
two or more taxa, but not the common ancestor of those taxadefined by at least one similar character that evolved independently (by convergent or parallel evolution)they share some superficial similarity, not because they're closely related to one another
phylogenetic trees
are hypotheses about the evolutionary relationships among a group of organismswe develop these hypotheses by observing shared and/or unique traits (characters) in the taxa to be studied
parsimony
the shorter tree or the one with the fewest changes this one wins
node
most recent common ancestor of 2 lineages
homoplasy
anything that makes your tree more complicated, or adds a step; like convergent evolution or losing a trait