Final answer:
A group of related species sharing a common ancestor is known as a clade or a monophyletic group. This relationship is illustrated through a phylogenetic tree, revealing the evolutionary connections and shared heritage of the species.
Step-by-step explanation:
A group of related species who together share descent from a common ancestor is called a clade or a monophyletic group. These organisms exhibit what is known as "descent with modification," meaning that they evolve from common ancestors and diversify over time, sharing genetic codes and characteristics. This concept is represented in a phylogenetic tree, a diagram that delineates how species are interconnected through their common ancestry.
The phylogenetic tree is a critical tool used in systematics, the study of the diversity of life and the evolutionary relationships among species. This diagram helps to illustrate the evolutionary history of organisms and the intricate relationships that have developed through the process of evolution. When scientists refer to a clade, they incorporate both the shared ancestor and all its descendants, which is central to understanding the lineage and heritage of species within the biological classification system.