Biology 1A    Sept 24, 1998
Lecture 8 - Systematics

Page Contents :

• Reading Assignment
• Overview of Lecture
• Lecture Outline
• Vocabulary
• Study Questions
• Related Websites

Stern: Chapter 16

Overview of Lecture:

Nomenclature is the science of naming organisms.
Taxonomy is the science of the classification of organisms.
Systematics is the science of the relationships of organisms.
Phylogenetics is the science of the pattern of evolution.

A. Evolution has created an enormous diversity, so how do we deal with it?
B. Names allow us to talk about groups of organisms.
1. Scientific names were originally descriptive phrases; not practical
2. Binomial nomenclature
a. Developed by Linnaeus, a Swedish naturalist
b. Names are in Latin, formerly the language of science
c. binomials - names consisting of two parts
d. The generic name is a noun.
e. The epithet is a descriptive adjective.
3. Thus a species' name is two words.

A. Taxonomy deals with the naming and ordering of taxa.
B. The Linnaean hierarchy:
1. Kingdom
2. Division
3. Class
4. Order
5. Family
6. Genus
7. Species
C. The nature of a hierarchy
D. The difference between classification and identification.

A. Systematics is the science of how organisms are related and the evidence for those relationships.
B. Systematics is divided primarily into phylogenetics and taxonomy.
C. Speciation -- the origin of new species from previously existing ones.
1. anagenesis - one species changes into another over time
2. cladogenesis - one species splits to make two

A. Evolutionary biology is the study of the processes that generate diversity, while phylogenetics is the study of the pattern of diversity produced by those processes.
B. The central problem of phylogenetics:
1. How do we determine the relationships between species?
2. Use evidence from shared characteristics, not differences
3. Use homologies, not analogies.
4. Use derived condition, not ancestral
a. synapomorphy - shared derived characteristic
b. plesiomorphy - ancestral characteristic
C. Cladistics is phylogenetics based on synapomorphies.
1. Cladistic classification creates and names taxa based only on synapomorphies.
2. This is the principle of monophyly.
3. monophyletic, paraphyletic, polyphyletic
4. Cladistics is now the preferred approach to phylogeny.

• Why is nomenclature important?
• Why was the development of binomial nomenclature so important?
• What is taxonomy, and how does it differ from nomenclature?
• What is a hierarchy? What are some examples of hierarchy?
• If an order of plants has twelve families and 400 species, what is the minimum number of genera possible in the order? What is the maximum number possible?
• To which level of the hierarchy would the group Liliales belong? Liliopsida? Liliaceae? Lilium michiganensis?
• Explain the difference between classification and identification. Which are you doing if you use a field guide to locate the name for a plant in your yard?
• How are cladogenesis and anagenesis different? How are they similar? Can cladogenesis occur by gradualism? by punctuation?
• What is the central problem of phylogenetics? What principles are used to solve this problem?
• Are the wings of insects and birds an example of convergence or homology?
• Which of the following characteristics are synapomophies for fungi? Which are plesiomorphies?
  multicellular
  chitin in cell wall
  eukaryotic
  sexual reproduction
  hyphae
• Diagram and explain the difference between monophyly, paraphyly, and polyphyly.
• Are the algae monophyletic, paraphyletic, or polyphyletic? What about fungi? What about eukaryotes?

• UCMP - Journey into Phylogenetic Systematics
• UCMP Glossary Vol. 1 : Phylogenetics
• UCMP - Phylogenetics Resources