Question

ul Bio220 - Diversity of Life HW 2: Phylogenetics First Some Review and Examples... There are several definitions that you will need to be familiar with in order to properly use and understand phylogenetic systematics. - Character: A heritable attribute of an organism. - Plesiomorphy: A primitive or ancestral character. This is a character that was inherited from a distant or ancient ancestor. - Apomorphy: A derived (new) character. An evolutionary novelty that arises new in a taxon, or in the most recent common ancestor of a clade. There are two types of apomorphies: 1. Autapomorphy: An autapomorphy is a derived character that is unique, meaning it is found in only one taxon in the cladogram. It is not useful for reconstructing the evolutionary relationships between taxa. 2. Synapomorphy: A synapomorphy is a shared derived character found in two or more taxa on the cladogram. It is the only kind of character used to arrange organisms into monophyletic groups - Polytomy: A polytomy shows unresolved relationships between taxa on a cladogram. Instead of a two-branched split from a node, three or more branches all emanate from the same node. This generally means that there is not enough data to determine the relationships, and shows systematists where more work needs to be done! (see image below) A B C D - Homology: Features found in two or more organisms are considered homologous if they are the result of common ancestry. One example is the fingers on your right hand, and the fingers on the right forefoot of a lizard. By reconstructing the phylogeny of both lineages, we can see that "fingers on the forelimb' is a character you and the lizard inherited from the same tetrapod ancestor. Therefore, the presence of these fingers is a homology between the two of you. -Homoplasy (analogy, convergence): This is similarity in form because of similar function, ecology habitat, etc., but not because of similar ancestry. A classic example is the wing of a bird and a bat. Each has wings and each uses them for flying. But the detailed structure of the wing is different, which raises suspicions as to its homology. The evolutionary history of both groups shows that they each independently evolved wings, and that they do not share a winged ancestor. Therefore, the wings of birds and bats are homoplastic, not homologous.

There are a total of 8 pages. If you click on the first picture, the others should pop up. Thank you!

Answer 1

Part I-

1) A. In the given figure, Q1 designates a node.

B. The node represents the common ancestor of the descendants.

2) Q2 designates apomorphy. It is the character that evolved with time and wasn't inherited fromancestors.

3) A. It represents paraphyletic group as it doesn't include the common ancestor "x".

B. It represents polyphyletic group as it includes members of the other group as well which are D and y.