Geology 105 - Paleontology
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Systematics

Reading: Chapter 4

We will use all of this material. Also read the Gould #1 article and use that information in answering the questions.

Background

Terms:

Key Concepts and Questions:

1. Basics of biological classification

A. Hierarchal groups:

Kingdom, Phylum, Class, Order, Family, Genus, Species

natural groups:

Kingdom; fundamentally different kinds of creatures (e.g., plant, animal, fungus, etc.)

Phylum - different body architectures (e.g., Arthropods have jointed appendages, segmented body, chitonous exoskeleton)

Family - recognizable kind of organism; e.g., squirrel, cat, human

Species - specific kind of organism; red squirrel, Asiatic lion, modern human

 

B. Naming: Suppose you find a fossil brachiopod? What do you have to do to name the species?

 

 

 

2. Why Classify?

A. To identify morphologic groups - organisms that look like the "same kind" of creature.

E.g., it's easier to refer to "fish" than to "vertebrate organisms with gills and fins that live in the water"

B. To represent evolutionary relationships.

Are all fish more closely related to each other than to other groups?

 

 

 

 

C. To create a database for answering biological questions, e.g., biodiversity

 

3. Three different approaches

A warning: cladistic analysis bristles with daunting terminology. Of all those terms, the only ones we need are: shared derived characters, cladogram, monophyletic.

A. Write brief definitions of evolutionary taxonomy, phenetics, and phylogenetic systematics:

Evolutionary taxonomy :

Phenetics:

Phylogenetic systematics (cladistics):

 

B. Comparing methods (start filling the chart out as you read and we'll finish it in class)

System	Evol. Taxonomy	Phenetics	Cladistics
Goal of classification
Methodology
What characters do you use?
What's objective, what's subjective

 

C. Why does it matter?

 

 

Assessment

1. Short Answer

• Compare the three schools of biological classification (traditional taxonomy, cladistics, phenetics) based on goals, methods, use of characters, and areas of objectivity/subjectivity.
• Under what circumstances may I choose the name of a new species? What must I do to make that name "official"?
• Using the example of human evolution in the last 200,000 years, explain what molecular systematics can tell us about the evolution of lineages and the assumptions inherent in the technique.

2. Essay

• Debate over cladistic classification is particularly bitter among paleontologists working on ancient reptiles, dinosaurs and birds. Here is a statement from the Web page of an evolutionary biologist:

Of [the three] basic approaches to taxonomy, I prefer the evolutionary approach. The reasons for this are summarized as follows:

1. The information content is higher.
2. It promotes greater stability.
3. It enhances ease of use.
4. It results in a more balanced classification.

Discuss this statement first from the viewpoint of an evolutionary taxonomist, then from a cladistic viewpoint. Use the example of the classification of reptiles, birds and mammals to argue each side. Be sure you address each of the points listed above for each of the classification systems.