Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta

Homologous Structures Derived From Leaves

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta 3. Comparative Physiology –C3, C4, CAM

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta 3. Comparative Physiology –C3, C4, CAM 4. Biochemistry –proteins and DNA

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta 3. Comparative Physiology –C3, C4, CAM 4. Biochemistry –proteins and DNA (macromolecules) (micromolecules) flavinoides – anthocyanin/ betalains - (10 fams) = Caryophyllales

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta 3. Comparative Physiology –C3, C4, CAM 4. Biochemistry –proteins and DNA 5. Vestigial Organs –staminoids

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta 3. Comparative Physiology –C3, C4, CAM 4. Biochemistry –proteins and DNA 5. Vestigial Organs –staminoids 6. Geographical Distribution –Continental Drift

Continents during Creataceous 100 mya

Geographically Separated, Morphologically Similar Plantanus occidentalis Plantanus hispanica

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta 3. Comparative Physiology –C3, C4, CAM 4. Biochemistry –proteins and DNA 5. Vestigial Organs –staminoids 6. Geographical Distribution –Continental Drift 7. Development -

Evidences of Evolution 1. Fossils 2. Comparative Morphology –Bessey’s Dicta 3. Comparative Physiology –C3, C4, CAM 4. Biochemistry –proteins and DNA 5. Vestigial Organs –staminoids 6. Geographical Distribution –Continental Drift 7. Development - 8. Selective Breeding –Brassica

Carboniferous Period 300 mya

Kingdom: Plantae 1. Waxy Cuticle 2. Gametangia –archegonia, antheridia 3. Embryos 4. Pigments 5. Thick spore walls – homosporous  heterosporous

Evolution from Green Algae to Plants

Nontracheophytes vs. Tracheophytes Tracheophytes have vascular tissue. –Xylem tracheids vessel elements –Phloem seive tubes comapion cells

First Tracheophytes (vascular plants): Division: Rhyniophyta Rhynia Cooksinia– M. Silurian 420 mya Rhynia – L. Devonian 360 mya

Phylum: Sphenophyta Horsetails

Phylum:Cycadophyta cycads

Phylum:Ginkgophyta ginkgo

Phylum:Gnetophyta Welwitchia

Phylum:Coniferophyta conifers

Phylum: Anthophyta flowering plants

Charles Darwin 19thC

Acquired Characteristics vs. Natural Selection Acquired characteristics –J. B. Lamarck Natural Selection –C. Darwin –A. Wallace

Darwin’s Tenets 1. Many more individuals are born than will survive. 2. There is variation among individuals. 3. Individuals with certain characteristics have a better chance of survival and reproducing than individuals with other characteristics. 4. At least some of the characteristics resulting in differential reproduction are heritable. 5. Enormous spans of time are available for slow, gradual change.

Species?? Groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups. –Ernst Mayr Harvard 1940

Evolutionary Divergence

Evolutionary Divergence Allopatric Speciation Allopatric Speciation

Phylogenetic Hierarchy Kingdom –Division (Phylum) Class –Order »Family » Genus » species

Isolating Mechanisms for Species (Character Displacement) 1. Mechanical (Reproductive) Isolation – flower structure –Aquilegia canadensis –A. formosa –A. ecalcarota –Asclepias 2. Habitat Isolation –Plantanus occidentalis –P. orientalis –P. acerifolia 3. Seasonal Isolation –Pinus radiata Feb. –P. muricata April

Enhancement of Cross-pollination (within species) 4. Mechanical 5. Chemical

Form an occasional variation within a species Scarlet Gilia –Red, Yellow Variety Chestnut Oak –var. accumata, var. prinoides

Population Genetics Alleles - color in scarlet gilia –RED (R) dominant –Yellow (r) recessive

Hardy - Weinberg Equilibrium Gene frequencies in a population will not change if: 1. No plant has an adaptive advantage. 2. No immigration or emigration. 3. No mutations.

Difficulties in interpreting Evolutionary Change Convergence - polyphyletic –Cactaceae, Euphorbiaceae Divergent - monophyletic –Lamiaceae, Verbenaceae

Interpreting Evolutionary Change 1. Vegetative characteristics are more liable to evolutionary change. (Also have a high degree of “genetic plasticity”.) 2. Reproductive characteristics are most conservative and are best for determining the evolution of taxa. “Good Characteristic” - heritable and not affected much by the environment.

Interpreting Evolutionary Change

Bessey’s Dicta 1. Woody plants came before herbs. 2. Perennials before biennials or annuals. 3. Alternate leaves are primitive; opposite or whorled are advanced. 4. Bisexual flowers are primitive. 5. Many parted spirally arranged flowers are primitive to all other arrangements.

Bessey’s Dicta 5. Many parted spirally arranged flowers are primitive to all other arrangements. 6. Hypogyny is primitive to epigyny and perigyny. 7. Numerous separate carpels are primitive to fewer fused carpels.

Bessey’s Dicta 8. Pollen grains with 1 pore preceded those with 1 or more pores. 9. Axile placentation preceded free central placentation. 10. Single fruits preceded aggregate fruits formed from several ovaries. 11. The capsule preceded the drupe or berry.

Mechanisms for Evolutionary Change 1. Gene Mutations - –changes in sections of the DNA on chromosomes (rare) 2. Chromosomal Mutations - –the normal (2n) chromosome number is not maintained –POLYPLOIDY 40% - 70% of plant species Autopolyplody

POLYPLOIDY mint species - Europe –Galeopsis pubsescens 2n = 16 (8 prs.) –Galeopsis speciosa 2n = 16 (8 prs.)

POLYPLOIDY mint species - Europe –Galeopsis pubsescens 2n = 16 (8 prs.) –Galeopsis speciosa 2n = 16 (8 prs.) –ALLOPOLYPLOID doubling of chromosome no. in 2 different species –Galeopsis pubescens X speciosa 4n = 32 artificial hybrid –Galeopsis tetrahit 4n = 32 natural species (one step evolution)

POLYPLOIDY –Modern Speciation –Spartina pectinata 2n = 62 USA –Spartina townsedii 2n = 60 Europe –Spartina pectinata X townsendii (4n) = 122 England 1870 sterile Spartina anglica (4n) 2n = 122 England 1890 fertile Allopolyploidy Sympatric Speciation - no geographical barrier

POLYPLOIDY Tragopogon Salsiflies, Goatsbeards –T. porrifolius –T. dubius –T. pratensis Allopolyploids: Sympatric Speciation –T. miscellus 4n T. pratensis X dubius (chloroplasts) –T. mirus T. pratensis X porrifolius Allopolyploids more common than diploids today.

Polyploids Diploids vs. Polyploids

POLYPLOIDY –Raphanus (radish) X Brassica (cabbage) --> 4n tetraploid – 2n 2n

3. Reshuffling or Recombination of Existing Genes Normal Diploid Condition (2n) Homologous Pairs Crossing over - Arboreous (A), Fruticose (a) L. leaves (L), S. leaves (l) A a L l

3. Reshuffling or Recombination of Existing Genes Normal Diploid Condition (2n) Homologous Pairs Crossing over - Arboreous (A), Fruticose (a) L. leaves (L), S. leaves (l) a A L l

3. Reshuffling or Recombination of Existing Genes Random Assortment –how the different chromosomes combine in gametes Fertilization –the many different combinations in eggs and sperm combine

Modern Theory of Organic Evolution 1. There is a tremendous amount of variability in the gene pool of each organism (each species). 2. Organisms have changed through time. 3. Evolutionary change is directed by natural selection.

Evolutionary Change A change in the gene frequency of a gene in a gene pool. If an organism is incapable of changing as the environment changes? EXTINCTION

Classification Theories ( Attempts to Determine “Natural Groupings”) Traditional Taxonomy, Traditionalists –Are not opposed to making value judgments (weighted characteristics) in construction phylogenetic trees. Use para and polyphylogeny Phylogenetic Taxonomy, Cladists –Use only objective data when constructing monophyletic evolutionary trees. Also use computers and numerical comparison of unweighted characteristics for cladograms.