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SIO 133 Discussion Section -- Week 3
1. Lecture 5: Cetacean Systematics & Evolution
2. Lecture 6: Pinniped, Sirenian, Polar Bear and Sea Otter (Taxonomy)
3. Lecture 7: Pinniped Systematics and Evolution
------------------------------------------------------------------------------I.
Taxonomy – What you need to know:
a. Characteristics of
i. Class Mammalia
ii. Three Orders of marine mammals
iii. Every Family, PLUS know one example (common and binomial name) of each
Family.
iv. Be able to compare/contrast Mysticeti and Odontoceti
v. Be able to compare/contrast sub-families of Phocidae and Otariidae
II.
Term Paper Reminder
a. 5-7 page research paper on a unique/individual topic
b. Details, description and guidelines up on the website (http://cetus.ucsd.edu/sio133/)
c. Milestones (Due via email):
i. Selected Topic
– April 27
ii. Outline/References
– May 11
iii. Draft (Submission OPTIONAL) – May 18
iv. Final Paper Due
– June 1
III.
Trouble selecting a paper topic? Browse through:
a. Marine mammal guide books
i. Marine Mammals of the World (Eds. Jefferson, Webber, Pitman)
ii. Encyclopedia of Marine Mammals (Eds. Perrin, Thewissen)
b. Websites
i. www.arkive.org
ii. www.iucnredlist.org
iii. www.marinemammalscience.org/species-information/
iv. Beware of Wikipedia
Lecture 5: Cetacean Systematics & Evolution ---------------------------------------------------------------
1) Define the following terms:
a) Systematics
b) Phylogeny
c) Cladistics
d) Characters
SIO 133 Discussion Section -- Week 3
2) What is the hierarchical structure below called? What does it represent? What do we call each
junction on the tree (where the red # 1 is, for example)?
3) If the structure above is organized correctly, organisms above a given node (typically to the right
and/or up) on the tree to share common characters. What are those shared characters called?
4) A clade is any lineage, or area that is defined on a given tree. Define what is meant by a
monophyletic clade? A polyphyletic clade? A paraphyletic clade?
5) True or false: Marine mammals are a monophyletic group? Why/Why not?
SIO 133 Discussion Section -- Week 3
6) What are derived versus ancestral characters? What method is used distinguish between the two?
7) What 3 epochs are particularly important in cetacean evolution? What era are these part of?
8) What is another name for the “ancient whales”? Fill in the table below, then use the Family names
to fill in the tree above.
Family
Pakicetidae
Ambulocetidae
Remingtonocetidae
Protocetidae
Basilosauridae
Dorudontidae
Time period
Habitat
Derived Character(s)
Lecture 6: Pinniped, Sirenian, Polar Bear and Sea Otter (Taxonomy) --------------------------------------------1) Name three morphological differences between Otariids and Phocids.
2) What are two characters shared between odebenids and otariids, but not phocids? How about
two characters shared between odebenids and phocids, but not Otariids?
3) What Order contains Pinnipeds? Sea otters? Polar Bears?
4) Contrast the vocal repertoire of ringed seals and ribbon seals. What about the ecology of these
two species might explain those differences?
SIO 133 Discussion Section -- Week 3
5) Fill in the table below with some traits of each taxonomic group, and one example of each
Family:
Name
Order Carnivora
Example organism
All carnivores
Suborder Pinnipedia
(“feather footed”)
All seals, sea lions
and walruses
(3 families, 36 spp)
Some features
-eat primarily animal tissue, low density, tend to be apex
predators
Family Phocidae
Subfamily Phocinae
Northern seals (10
spp)
Subfamily Monochinae
Southern,
Antarctic, Elephant
and Tropical seals
Family Otariidae
Subfamily Otariinae
Seal lions (7 spp)
Subfamily Arctocephalinae
Fur seals (9 spp)
Family Odobenidae
Order Sirenia
Family Dugongidae
Family Trichechidae
Family Mustelidae
Family Ursidae
Dugongs/Manatees
2 Families (4 spp)
- smaller claws
- more developed dentition
- Include the crabeater seal, the most numerous marine
mammal
SIO 133 Discussion Section -- Week 3
Lecture 7: Pinniped Systematics and Evolution ----------------------------------------------------------------------
1) Are marine carnivores are a monophyletic group? Why/Why not?
2) Give one example of a homologous structure common to all pinnipeds.
3) Which order of marine mammals would you expect to be the most marine adapted? Why? List
three lines of evidence to support your answer.
4) Which is more adapted to life in the marine environment seals or sea lions? Why?
5) What is the most primitive group of extant pinnipeds?
6) Compare the current and historical diversity of walruses.
7) What is the only extinct Order of marine mammals?
8) Place these in order from oldest to youngest: Phocids/Odobenids/Otariids/Sirenians/Polar Bears
Oldest  ________, _________, _________, __________, __________  Youngest