evolutionary history of related organisms
Phylogeny. The evolutionary history of a group of genetically related organisms is called a phylogeny. It includes ancestor species and descendant species. A phylogeny is usually represented by a tree diagram called a phylogenetic tree. cladogram shows how species may be related by descent from a common ancestor. A classification of organisms on the basis of such relationships is called a phylogenetic classification. A phylogenetic classification involves placing organisms in a clade with their common ancestor. Consider the cladogram in Figure below.