phylogenetic trees

phylogenetic tree

shows the evolutionary history of a group of organisms

branch

represents a population through time

node

most recent ancestor (where branch splits)

tip

endpoint of a branch (still living)

sister taxa

any taxa derived from a common ancestral node

synapomorphy(shared derived characteristics)

features that species share

outgroup

sister group that shares a recent common ancestor with taxa being studied, but is not part of the study group to help root the tree (used to establish whether trait is ancestral or derived)

ancestral trait

trait that existed in an ancestor

derived trait

modified form of ancestral trait found in descendant

parsimony

tree with least evolutionary change is likely most accurate

monophyletic

a common ancestor and all of its descendants

paraphyletic

common ancestor and some but not all of decendants

polyphyletic

does not include common ancestor

homologous

similar due to shared ancestry

analogous

similar but not because of shared ancestry

convergent evolution

created analogous traits because of natural selection of environmental pressures

coevolution

the process in which species evolve together, responding to selective pressures from the other