Are animals a monophyletic group?
Monophyletic groups include all organisms in taxa that share a most common recent ancestor, including the ancestor. The consensus of current opinion is that all animals, including sponges, were derived from one common ancestor, and, hence, are monophyletic.
Is the group defined by the red color a monophyletic group?
A phylogenetic tree: both blue and red groups are monophyletic. The green group is paraphyletic because it is missing a monophyletic group (the blue group) that shares a common ancestor—the lowest green vertical stem.
What is not a monophyletic group?
A monophyletic group, sometimes called a clade, includes an ancestral taxon and all of its descendants. A monophyletic group can be separated from the root with a single cut, whereas a non-monophyletic group needs two or more cuts.
What are the similarities and differences between Cladograms and phylogenetic trees?
A phylogenetic tree is an evolutionary tree that shows the evolutionary relationships between different groups of animals. Cladograms give a hypothetical picture of the actual evolutionary history of the organisms. Phylogenetic trees give an actual representation of the evolutionary history of the organisms.
What is a shared derived trait?
The shared derived character is shared specifically with a common ancestor to other species that also share that character but not to ancestor of that specific common ancestor. See equivalently synapomorphy. Mammals, for example, are defined by their hair and production of milk, both of which are unique to that taxon.
What kind of trait is important to Cladistics?
In cladistics, the sharing of derived traits is the most important evidence for evolutionary relationships. Organisms with the same derived traits (such as feathers) are grouped in the same clade. A derived trait is not necessarily an entirely new trait. More often it is a modified form of an ancestral trait.
What is a ancestral trait?
As a reminder, an ancestral trait is what we think was present in the common ancestor of the species of interest. A derived trait is a form that we think arose somewhere on a lineage descended from that ancestor.
Is hair a derived trait?
It is not always obvious which character states are derived and which ancestral. Hair is derived for mammals (relative to other [non-mammalian] vertebrates), but ancestral for humans, because the closest relatives to humans, gorillas and chimps, also have hair.