What is a monophyletic group?

What is a monophyletic group?

• A. A group formed by convergent traits in unrelated species.
• B. A group that includes species from different lineages without a common ancestor.
• C. A group consisting of a common ancestor and all of its descendants.
• D. A group defined by shared ecological function rather than ancestry.

Answer: (C)

A monophyletic group, or clade, is defined by a single common ancestor and all of its descendants. This means every member traces back to that ancestor, and nothing outside that lineage is included. The description that best fits this idea is the one stating a group contains a common ancestor and all of its descendants. The other ideas describe different ways of forming groups: convergent similarities in unrelated species don’t reflect a single shared lineage, grouping species from different lineages without a common ancestor isn’t a true clade, and organizing by ecological function focuses on role rather than ancestry, which isn’t how a monophyletic group is defined.

A monophyletic group, or clade, is defined by a single common ancestor and all of its descendants. This means every member traces back to that ancestor, and nothing outside that lineage is included. The description that best fits this idea is the one stating a group contains a common ancestor and all of its descendants. The other ideas describe different ways of forming groups: convergent similarities in unrelated species don’t reflect a single shared lineage, grouping species from different lineages without a common ancestor isn’t a true clade, and organizing by ecological function focuses on role rather than ancestry, which isn’t how a monophyletic group is defined.