phylogenetic tree

The evolutionary history of a group of organisms organized as a branching tree. This diagram organizes the relationships of organisms by their most recent common ancestors.

The lengths of the lines (called lineages) can represent genetic change, with longer lines representing greater change over time than shorter lines.

More commonly, the lengths of lines on trees are used to indicate time. The base of the tree is rooted in the past. The tips of lineages represent the present. Lineages that stop short may be used to indicate extinct taxa.