Download Biological Diversity and Systematics EEOB 405.01

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
1
1
0
Rose
Catbriar
Pea
Pine
P
C
Pine
Stipules Compound leaves
1
1
0
0
1
1
0
0
C
R
P
R
C
P
Pine
Pine
Spines
0
Stipules
Compound lvs.
R
How do we choose which pattern to accept?
Parsimony
C
P
P
R
C
R
Pine
Pine
Stipules
Compound lvs.
Spines
Steps = 4
Spines
Stipules
Compound lvs.
Steps = 5
Monophyly, paraphyly
Genus A -- monophyletic
Genus 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 taxa
No real ancestors
(nodes are
hypothetical)
A Cladogram is not exactly a Phylogenetic Tree
Phylogenetic tree:
Can show ancestors and
relationships among all
units
A Cladogram is not exactly a Phylogenetic Tree
D
A
B
C
D
C
E
B
A
E
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 Generations
Does the organism have two distinct ploidy phases?
-- Gametes do not count
-- Phases defined by meiosis and recombination
-- Gametophyte and sporophyte
Cladophora
Fungi
Yeasts
Cup fungi
‘Mushrooms’
Algae
Green
Red
Brown
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).
How can a new, fertile species arise via hybidization?
Chromosome
doubling
(tetraploid)
Polyploidy can restore fertility by restoring the
condition of paired chromosomes.
Polyploidy by non-disjunction of chromosomes
(allopolyploidy) is common and relatively easily recognized.
Example of a weird, mutant, polyploid plant: