Final answer:
The root of a phylogenetic tree represents the common ancestor to all species depicted in the diagram, which shows evolutionary relationships based on genetic or physical traits. Charles Darwin sketched the first phylogenetic tree, and while these continue to be foundational, new DNA evidence occasionally leads to new understanding and changes in the trees.
Step-by-step explanation:
In a phylogenetic tree, the root represents the common ancestor of all the species included in the tree. This type of diagram is a tool that shows the evolutionary relationships among various biological species by illustrating how species are related through common ancestors.
The phylogenetic tree is comprised of nodes, branches, and a single trunk where the trunk indicates the most common ancestor. The internal nodes signify ancestral species that, based on scientific evidence, are thought to have diverged, giving rise to two or more new species. Charles Darwin was the first to sketch a phylogenetic tree, which has served as a foundational model for understanding biological evolution. Nonetheless, with advances in DNA sequencing and computational algorithms, our understanding and representation of these evolutionary relationships continue to evolve.