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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 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: