Plant systematics and Darwinian evolution
Evidence for Evolution

PLANT SYSTEMATICS AND DARWINIAN EVOLUTION
        I. The Diversity of life
                A. Biological diversity
                        1. Total diversity of life: 5 million to over 30 million species
                B. How can things that look so different be the same?  How can things that look the same be so different?  Example: Brassica oleraceae: Cauliflower, Broccoli, Kale, Brussels sprouts, Cabbage, Kohlrabi.
        II. Definitions
                A. Species: reproductively isolated breeding population; share a close common ancestry
                C. Evolution: process by which life forms change and new ones come into being
                E. Phylogeny: evolutionary relationships and history of a species
                B. Taxonomy: branch of biology; naming and classifying organisms
                D. Systematics: the field of biology concerning the scientific study of organisms and their phylogenic relationships
        III. Taxonomy
                A. Common names
                B. Scientific names
        IV. History of taxonomy
                A. Before 400 BCE
                B. Theophrastus:  400 - 300 BCE
                C. Pliny the Elder 23-79 AD
                D. Dioscorides: 1st Century AD
                E. Revival of Botany: Early Renaissance, 15-17th Century AD
                F. Taxonomy systems used today:
                        1. Carolus Linnaeus (1701-1778): Father of taxonomy; wrote Species Plantarum in 1753; Established binomial system of nomenclature.  Developed taxonomic hierarchy: Kingdom, division (or phylum), class, order, family,
                            genus, species
                        2. Taxonomic hierarchy
                                a) Five or six kingdom classification schemes
                                b) Kingdoms are grouped into three domains: Bacteria, Archaea, Eukarya
                        4. Challenging Linnaeus’ classification system with current DNA data
                                a) The closest living relatives of land plants are the green algae called Charales
        V.Is evolution the reason for life’s diversity?
                A. Before Darwin (1700’s)
                        1. Natural theologians: C. Linnaeus; G. Cuvier (catastrophism); J. Hutton (gradualism); C. Lyell ( uniformitarianism);  JB Lamarck  (inheritance of acquired characteristics)
                B. 1859, Charles. Darwin published On the Origin of Species:
                        1. Species evolved
                        2. Natural selection
                C. Artificial selection: selecting and breeding plants/animals that possess desirable traits.  Human manipulation of genes
                D. Concept of natural selection:
                        1. Variation: individuals vary and this variability is heritable
                        2. Overproduction:  each species produces more offspring than will survive to maturity due to limited resources.
                        3. Competition:  organisms compete with one another for limited resources and some are better able to compete
                        4. The Bottom line:  individuals that are selected by being ‘most fit’ for the environment must be able to produce more offspring and so pass on the successful genes within the population.  Each organism fit for their
                            particular environment; develops diversity.

EVIDENCE FOR EVOLUTION
        I. Extant species
                A. Biogeography
                B. Comparative anatomy (homologous structures)
                C. Modern advances in DNA sequencing methods
        II. Extinct species
                A. The fossil record found in sedimentary rock
                        1. Fossils form an incomplete record of the origins of plants.  The best plant fossils are pollen, wood, and leaf imprints.
                B. Similarities in chloroplast pigments/structure, cellulose cell wall, starch, mitosis and cytokinesis link the land plants to green algae.
                C. Convergent evolution = when similar traits arise independently in two groups of organisms
                        1.  Cactus vs. Euphorbs
                        2.  Mimicry (stoneplants)