OnRamps Biology Practice Test

Phylogenetic trees illustrate evolutionary relationships among species. They show how lineages split from common ancestors, with branch points representing those hypothetical ancestors and closer-together branches indicating more recent common descent. The root marks the earliest ancestor of all the depicted lineages, and branch lengths can reflect time or amount of evolutionary change when scaled. This type of diagram is about ancestry and relatedness, not about how energy moves through ecosystems, how chromosomes are arranged in cells, or how information flows in metabolism.