What is Clade?

In biology and biological taxonomy, a Clade group consisting of a single common ancestor, all descendants of this ancestor and nothing else. Over the centuries of work, biological taxonomy has tried to divide groups into caps and reject the classification of non-spanks, which are referred to as "paraphyletic". Real Clads are "monophyletic".

I can be birds. Birds believe that everyone descends from an ordinary ancestor who lived about 150 million years ago. However, reptiles and apes are not trunks. Reptiles are not Clade, because birds from dinosaurs, considered reptiles and birds are not considered reptiles. The group that excludes the descendants of the common ancestor is not. Apees is not an assertion because people from apes and humans are generally not considered apes. If you include people and extinct relatives of people, such as Neanderthals, to be apes, then apes are a benefit, but this is generally not happening.

simpler organisms such as arthropods (crustaceans, insects, mills andtd.), are more difficult to arrange in the pins because there are less genetic and morphological features that can be used to determine common ancestors and ancestors. For example, for decades at the end of the 20th century, scientists have thought that arthropods (animals with ex -enosteletons and connected attachments) had evolved on several separate occasions from soft body ancestors such as Annelid Worms. The following morphological and genetic analysis found that it is false-members are really putting, descending from a common ancestor that will divide from ancestors of soft bodies only once.

Plans at a level more specific than phyla can be demanding, especially in relatively simple animals. After decades of study, we still do not know how different groups of arthropods are connected. Did the land arthropods evolve from a fairy shrimp or other groups? We do not know with certainty and scientists are busy publisa look and performing analyzes to find out.

Clades determination is partly difficult, because most morphological and genetic data is ambiguous. Sometimes a certain morphological feature - as a spine - develops a parallel development rather than a manifestation in a single species and most (or all) of its descendants. Genetic data may be ambiguous because evolution occurs in different types of different speeds and throws out calculations that try to date divergence between species by comparing genetic common. To make matters worse, morphological specialists and genetics specialists tend to argue about the relative importance of their respective approaches. The correct determination of animal silica has occurred only after years or decades of deep research representing hundreds or thousands of articles and studies.