BIO 153 - P2

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