Final answer:
On phylogenetic trees, splits where lineages divide into two are represented by nodes, which are the points known as branch points, where a single lineage evolves into distinct new ones.
Step-by-step explanation:
When lineages divide into two on phylogenetic trees, these splitting events are represented by nodes. Phylogenetic trees and cladograms function as graphical representations of evolutionary history that can be tested. The specific point where a split occurs is known as a branch point. At a branch point, sister taxa emerge from the same ancestral lineage, indicating that they are closely related and share a more recent common ancestor. Another term used for a branch point is a node, which is where a single lineage evolves into distinct new ones. An unbranched lineage that evolved early is referred to as a basal taxon, and a branch with more than two lineages is a polytomy, illustrating unresolved evolutionary relationships.