Chapter 4: Estimating Evolutionary Trees

Phylogeny

Pattern and timing of evolutionary branching events ("evolutionary tree")

Independent

change in one character does not induce change in another character

Homologous

a trait shared because of inheritance format common ancestor

Synapomorphy

a shared, derived characteristic from a common ancestor

Cladogram

a phylogenetic tree inferred clustering synapomorphies

Convergence

trait adapted to a similar function but with a different origin

Reversals

(AKA back mutations) of a character state can remove synapomorphies

Homoplasy

similarity in the character found in different species that is due to convergent evolution and reversal

Parsimony

a criterion for selecting among alternative patterns based on minimizing the total amount of evolutionary change

Systematics

a scientific field devoted to the classification of organisms

Phenetics

a classification scheme based on grouping populations according to similarities

Cladistics

a classification scheme based on evolutionary relationships (phylogenies)

Monophyletic groups

including an ancestor and all of its descendants ("clade")

Paraphyletic Group

a set of species that includes an ancestor but NOT all its descendants

Root

the base of the tree, the locations of the common ancestors

Ancestral

the original character state in a group; opposite of "derived

Derived

a newly-evolved character state; opposite of ancestral