phylogeny

the history of the evolution of a species or group especially in lines of descent and relationships among broad groups of organisms.

homologous structures

organisms whose features overlap both morphologically (in form) and genetically. share an embryonic origin

analogy

when similar characteristics occur because of environmental constraints and not due to evolutionary relationships

analogous organs

have a similar function

molecular systematics

use of molecular data in taxonomy and biological geography

cladistics

system that sorts organisms into clades, which is a group of organisms descended from a single ancestor

monophyletic group

a single clade

phyletic

evolutionary relationship

shared ancestral characteristics

characteristics found in the ancestors of the group, all organisms in the taxon or clade have that characteristic/trait

shared derived characteristics

only some of the organisms in the group have the trait. this trait is derived at some point but doesn't include all the ancestors in the tree.

maximum parsimony

events occurred in the simplest most obvious way