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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, [email protected]
Office 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.
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.
Reconstructing relationships
• Intuitive classifications
• Cladistics– Direction is important– Indicated by shared derived characters
(synapomorphies)
Cladograms, characters
Spines Stipules Compound leavesRose 1 1 1Catbriar 1 0 0Pea 0 1 1
Pine 0 0 0
Spines
RCP
Pine
Stipules
Pine
RC P
Compound lvs.
Pine
RC P
Parsimony
How do we choose which pattern to accept?
RCP
PinePine
RC P
StipulesCompound lvs.Spines
StipulesCompound lvs.
Spines
Steps = 4 Steps = 5
Monophyly, paraphyly
Genus A -- monophyleticGenus B -- paraphyletic
The Key: a common ancestor and its descendants
A basic cladogram
Hypothetical ancestors
A Cladogram is not exactly a Phylogenetic Tree
Cladogram:
A network of characters and taxaNo real ancestors (nodes are hypothetical)
Phylogenetic tree:
Can show ancestors and relationships among all units
A Cladogram is not exactly a Phylogenetic Tree
A B C D E
A
B
C
D E
A Cladogram is not exactly a Phylogenetic Tree
Five Kindoms, of Margulis and Schwartz (1988)
A traditional, non-cladistic phylogeny of plants (Cronquist, ~1950)
A modern cladistic phylogeny of life, based on RNA gene sequences.
Alternation of GenerationsDoes the organism have two distinct ploidy phases? -- Gametes do not count -- Phases defined by meiosis and recombination -- Gametophyte and sporophyte
Cladophora
Fungi
Cup fungi
‘Mushrooms’
Yeasts
Algae
BrownRed
Green
Flowering plants
What is a species?
Biological Species Concept
Morphological Species Concept
Genetic Species Concept
Paleontological Species Concept
Evolutionary Species Concept
Modes of speciation in plants
Tulip Tree – Liriodendron tulipifera
Modes of speciation, continued.
Hybridization is relatively common in plants.
What happens during hybridization?
But, many hybrid plants can continue to reproduce vegetatively (asexually).
Chromosome doubling (tetraploid)
Polyploidy can restore fertility by restoring the condition of paired chromosomes.
How can a new, fertile species arise via hybidization?
Polyploidy by non-disjunction of chromosomes (allopolyploidy) is common and relatively easily recognized.
Example of a weird, mutant, polyploid plant: