Phylogenetic Trees

Phylogenetic Tree

a visual representation of the relationship between species, taxa, individual, population, etc.

Node

a hypothetical ancestor, usually denotes a speciation or separation event

Branch

represents the evolution of a lineage

Tip

species, individual, or other entity that we are studying

Operational Taxonomic Units (OTU)

technical term for the tip in the tree

Ingroup

the subgroup of interest in a study

Outgroup

one or more species included to provide the direction in a phylogenetic study

Root

...

Putative Ancestor

...

Clade

a species, meaning an ancestor, and all of its descendants

Monophyletic

a taxonomic group consisting of all descendants of the group's most recent common ancestor and nothing else

Polyphyletic

a disjointed group of descendants

-ex: pachyderms

Paraphyletic

a group that does not contain all of the descendants of the group's most common ancestor

Sauropsida

the monophyletic group that includes all birds and reptiles (including dinosaurs)

Reptiles

a paraphyletic group that doesn't include birds

Vertebrates

the monophyletic group that includes fishes, birds, mammals, etc

Fishes

a paraphyletic group that doesn't include tetrapods

Cladogram

tree with no information in the branch lengths

Phylogram

tree with evolutionary change (molecular change) represented as the branch lengths

Chronogram

1) tree with time represented as the branch lengths

2) helps include extinct organisms and fossil into the tree of life

Ancestral Trait

the trait in the ancestral population or species that unless lost will be inherited

Derived Trait

the trait that has changed state from the ancestral form

Homologous Traits

1) traits that are found in a set of species because they are inherited

2) come from parallel evolution

Analogous Traits

1) traits that are found in a set of species but not because of shared ancestry

2) come from convergent evolution

Synapomorphy

a shared derived trait

Homoplasy

a trait shared by closely related species but not the ancestor

Symplesiomorphy

a derived trait that only present in one or two resent species - not in the ancestor