Which describes a paraphyletic group?

Which describes a paraphyletic group?

• A. An ancestor and all of its descendants.
• B. An ancestor and some, but not all, of its descendants.
• C. A group with no shared recent ancestor.
• D. A group defined by convergent traits.

Answer: (B)

Paraphyletic groups include a single common ancestor and only some of its descendants. This means the group traces back to that ancestor, but one or more descendant lineages are left out. That exact idea is captured by describing a group as containing the ancestor and some—but not all—of its descendants. This differs from a monophyletic group, which includes the ancestor and all of its descendants, forming a complete clade. A group described as having no sharedRecent ancestor or being defined by convergent traits tends to be polyphyletic, because the members are gathered by features that don’t reflect one recent common ancestry. An example is treating birds as reptiles; birds are descendants of the same ancestor as reptiles, so excluding birds from a reptile group makes it paraphyletic.

Paraphyletic groups include a single common ancestor and only some of its descendants. This means the group traces back to that ancestor, but one or more descendant lineages are left out. That exact idea is captured by describing a group as containing the ancestor and some—but not all—of its descendants.

This differs from a monophyletic group, which includes the ancestor and all of its descendants, forming a complete clade. A group described as having no sharedRecent ancestor or being defined by convergent traits tends to be polyphyletic, because the members are gathered by features that don’t reflect one recent common ancestry. An example is treating birds as reptiles; birds are descendants of the same ancestor as reptiles, so excluding birds from a reptile group makes it paraphyletic.