What is a phylogeny?

Niklas Wahlberg

A phylogeny portrays the genealogical relationships of species and groups of species in a tree-like diagram. Such a diagram, known as a cladogram or phylogram, shows how lineages are related to each other and which lineages share a common ancestor to the exclusion of all other lineages. A phylogeny can never be observed, and thus has to be inferred from the distributions of characters and character states in current living species. A robust phylogenetic hypothesis for a given group of species can be used to investigate the evolutionary history of the species, including where, when, how and why the ancestors of the species diverged to form the species of today.