Clades
A clade is a group of organisms that have evolved from a common ancestor, it is also called a monophyletic taxon.
A taxon is any group of species, a monophyletic taxon contains only the descendants of the common ancestor. (contains one ancestor which can be an organism, population or species of all its descendants) Non-clade classifications are called 'paraphyletic' True clades are called 'monophyletic' Examples of Clades:
|
Birds are considered to be true clades as they are believed to be descended from one common ancestor about 150 million years ago. On the other hand, Reptiles and apes are not considered to be a clade since birds descended from reptiles and birds are not considered a reptile. In summary, if a group excludes descendants of a common ancestor is not a clade. (Apes are not considered a clade too because we are descended from apes but we aren't considered to be apes.)