Biological Diversity and Systematics

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Biological Diversity and Systematics EEOB 405.01
- Spring Quarter 2002 Weeks 8-11 Fungi and
Plants   Instructor Dr. Andrea D. Wolfe, 326 B
Z, 1735 Neil Ave, 292-0267, wolfe.205_at_osu.edu Off
ice Hours by appointment (email works well for
contacting me)   Textbook Selected Chapters from
Botany, 2nd Ed. (1998) by Moore, Clark, and
Vodopich
Course goals Understand the broad features of
evolution within the fungi and selected taxa of
diverse photosynthetic organisms. This will
include knowledge of patterns of descent
(phylogenies) and the important traits that
document evolutionary trends within these groups.
We will also consider major features of the
ecology of these organisms and their economic
importance.
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• Outline Lecture 1 Plant evolution and phylogeny.
• Readings Chapters 23 24 in Moore et al.
•  
• A. Systems of classification.
• 1. Rise of cladistics, based on formal analysis
  of changes in characters over time and across
  groups.
• a. Evolutionary hypotheses can be formulated and
  tested.
• 2. Five kingdom classification by Margulis and
  Schwartz
• a. Based on traditional methods of systematics
  (1988).
• b. Modern phylogeny of life based on RNA.
• 3. Traditionally, all organisms containing
  chlorophyll a were put in plant kingdom.
• a. Our treatment of organisms will span three
  kingdoms.
• B. Overview of groups we will consider.
• 1. Fungi, Algae, Mosses, Ferns, Conifes,
  Flowering plants.
• C. Some important features of evolution in
  flowering plants.
• 1. Limited gene dispersal distances via pollen
  flow.
• 2. Hybridization as a route to speciation.
• a. Importance of polyploidy.

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Reconstructing relationships

• Intuitive classifications
• Cladistics
• Direction is important
• Indicated by shared derived characters
  (synapomorphies)

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Cladograms, characters
Spines Stipules Compound
leaves Rose 1 1 1 Catbriar 1 0
0 Pea 0 1 1 Pine 0 0 0
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Parsimony
How do we choose which pattern to accept?
Steps 4
Steps 5
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Monophyly, paraphyly
Genus A -- monophyletic Genus B -- paraphyletic
The Key a common ancestor and its descendants
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A basic cladogram
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A Cladogram is not exactly a Phylogenetic Tree
Cladogram A network of characters and taxa No
real ancestors (nodes are hypothetical)
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A Cladogram is not exactly a Phylogenetic Tree
Phylogenetic tree Can show ancestors and
relationships among all units
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A Cladogram is not exactly a Phylogenetic Tree
D
E
C
A
B
C
D
E
B
A
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Five Kindoms, of Margulis and Schwartz (1988)
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A traditional, non-cladistic phylogeny of plants
(Cronquist, 1950)
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A modern cladistic phylogeny of life, based on
RNA gene sequences.
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Alternation of Generations
Does the organism have two distinct ploidy
phases? -- Gametes do not count -- Phases
defined by meiosis and recombination --
Gametophyte and sporophyte
Cladophora
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What is a species?
Biological Species Concept
Morphological Species Concept
Genetic Species Concept
Paleontological Species Concept
Evolutionary Species Concept
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Modes of speciation in plants
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Tulip Tree Liriodendron tulipifera
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Modes of speciation, continued.
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Hybridization is relatively common in plants.
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What happens during hybridization?
But, many hybrid plants can continue to reproduce
vegetatively (asexually).
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How can a new, fertile species arise via
hybidization?
Polyploidy can restore fertility by restoring the
condition of paired chromosomes.
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Polyploidy by non-disjunction of chromosomes
(allopolyploidy) is common and relatively easily
recognized.
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Example of a weird, mutant, polyploid plant