Question

3. (4 pts) Although modern scientific classification avoids paraphyletic groups, there are some paraphyletic groups (based on their common names) that herpetologists study. Name one such group and what relationships make it paraphyletic. 4. (3 pts) Define the following terms, and tell which one is useful in estimating phylogenies: a) Synapomorphy b) Plesiomorphy
PLEASE HELP me solve BOTH 3 and 4, SHOW ALL WORK EXPLAIN IT WELL, thank you!!

Answer 1

3Q/Ans--A group is paraphyletic,if it consist of the group's last common or single ancestors and all descendants of that ancestors excluding a few-typically only one or two.One such group and their relationship which makes it paraphyletic is;

THE BLUE POLYGON AND THE YELLOW POLYGON,each enclose a paraphyletic grouping. In the case of blue polygon,Taxon A,Taxon B,Node1 and Node2 are included in the group but Taxon C is excluded. This group is paraphyletic because it doesn't include all the descendants of the common ancestors by Node2. whereas ,the yellow polygon also represents the same paraphyletic group(i.e..,Taxon C is missing from the group).Hence it is called as Paraphyletic group.

4Q/ANS--

a)SYNAPOMORPHY-The concept of synapomorphy is relative to a given clade in the tree of life. Synapomorphy is important because they constitute the evidence for common ancestry,associated monophyletic groupings and thus the historical relationships depicted in cladograms.

example:The presence of mammary glands is a synapomorphy for mammals in relation to tetrapods but is symplesiomorphy for mammals in relation to one another.Rodents and Primitive(example)

b)PLESIOMORPHY:It refers to a primitive or ancestral trait.It is a character state that is present in both groups and in the ancestors. (It is cladistics)

example:A segment spinal column is a plesiomorphy of mammals.

Plesiomorphy is useful in estimating Phylogenies.