It is called phylogeny to the branch of the biology focused on kinship ties that exist between different sets of living beings. In this discipline the notion of monophyletic to allude to group formed by the species that evolved from a common ancestor .
A monophyletic group, thus, is composed of organisms that share a same ancestor as origin . In this kind of group , all the members of the genre come from a certain ancestral form. On the other hand, if in the group there are beings that do not descend from the ancestor in common, it is qualified as paraphiletic .
The gender Homo , for example, is monophyletic. Experts believe that all of the species that compose it have evolved from the same ancestor, which is part of the family of hominids (biped primates) The Homo sapiens (that is, the current human being) is the only living species of this monophyletic group, which also includes the Homo rudolfensis , he Homo habilis , he Homo floresiensis and the Homo Neanderthalensis , among others.
The monophyletic groups, in short, gather biological taxa that share an ancestor in their history evolutionary This means that they include all descendants of the same ancestor. The paraphyletic groups they do not cover all descendants, while polyphyletic groups They present taxa of different origins.
A monophyletic taxon part of a organism TO , from which the species descend B and C . From B , in turn, descend D and AND ; from C descend F and G . As you can see, the species B , C , D , AND , F and G they have the same ancestor in common: the organism TO . That is why it can be said that it is a monophyletic group.