BOTV102 Systematics PDF

BOTV102 SYSTEMATICS: Introduction: Systematics – study of diversification of living forms, both past and present, and the relationships among living things through time – = taxonomy (aim is to correctly draw tree of life) Taxon – name applied to any group Taxa – have a...

BOTV102 SYSTEMATICS: Introduction: Systematics – study of diversification of living forms, both past and present, and the relationships among living things through time – = taxonomy (aim is to correctly draw tree of life) Taxon – name applied to any group Taxa – have a rank in the hierarchy Major taxa: KEY - Domain ∽ Group - Kingdom * Empire - Division Domain - selected Classes o Kingdom - selected Families  Division  Reason Life is hierarchical in its nature:  Reproduction - tree of life (mostly prokaryotes)  Other - cladogram or phylogeny - Other - circle of cladograms Phylogeny – evolutionary history Tree of life: NOMENCLATURE: Why scientific name? - Common names not universal, only applied in one language - Common name does not provide information on relationships - Same plant – many common names - Two/more plants – same common names - Many species – no common name Taxonomic hierarchy: Division -phyta Class -opsida Order -ales Family -aceae Genus (pl. genera) Species Subspecies Variety Subvariety Infraspecific taxa Form Subform Generic name: (Portulacaria afra Jacquin) - Initial capital letter - May be abbreviated (after being used once in full) - Underline or italicised Specific epithet: (Portulacaria afra Jacquin) - Initial lowercase letter - Never abbreviated - Never written alone - Underline or italicised Authority: (Portulacaria afra Jacquin) - Always given the first time - May be abbreviated If name needs to change: Portulacaria afra Jacquin ↓ Crassula afra (Jacquin) Campbell & Lithauer CLASSIFICATION: Most fundamental grouping: - Mineralia (non-living) - Biota (living)  Has metabolism ∽Biota: - Empire Acytota (non-cellular life; viruses) - Empire Cytota (cellular life)  Cell membrane  Cytoplasm *Empire Acytota: - No cytoplasm, cell membrane or cellular structures (terms cell & cell membrane not applicable) - Extremely small particles; usually contain only protein and nucleic acid - Plant viruses have simple morphology; long/short rods or round particles - Protein coat separates nucleic acid from environment - Must invade living cell to reproduce - Viral nucleic acid is released in the cell and transcribed by it - DNA is also replicated by cell - Soon all metabolism is redirected to viral metabolism - Retroviruses (RNA, no DNA) may act as mRNA and be picked up and translated by a plant ribosome - Many viruses are interesting as possible vectors for plant genetic engineering (transductions) - Plant virus particles remain in cell until it is broken open by insects or larger animals - Non-plant viruses cause cell to burst (lyse) and release virus particles into environment - Origin (2 theories)  Remnants of cell nucleic acid  Highly evolved, super-parasites A) Non-enveloped virus: B) Enveloped virus Glycoproteins Nucleic acid  *Empire Cytota: - Domain Bacteria Prokaryotes. No structural difference, - Domain Archaea only metabolically different - Domain Eukarya Cladogram #1: Bacteria Archaea Eukarya Ether lipids in Peptidoglycans in cell wall cell membrane True nucleus - Simple RNA polymerase - N-formyl methionine is the - Histones protein initiator amino acid - Complex RNA polymerase - Methionine is the protein initiator amino acid -Prokaryotes:  No membrane-bound organelles  No protoplasmic connections between colonial cells  Never multicellular  Reproduction: - Binary fission (mitosis; not sexual) - Genetic exchange by:  Transformation - bacteria die, cell ruptures - DNA fragments are absorbed  Transduction - virus vector  Conjugation - specific structures (thin conjugation pilus stretched from one to other and DNA transported through it) Domain Bacteria:  Peptidoglycans in cell walls - Nitrogen fixing (in soil; make nitrogen for plants) - Nitrifying & denitrifying (decomposition)  Division Cyanophyta  Green because of chlorophyll a (photosynthesis)  Has heterocyst (fixes atmospheric nitrogen) Domain Archaea:  Ether lipids in cell membrane - Thermophilic (temperature) - Halophilic (salt) - Acidophilic (acid)  Domain Eukarya:  Membrane bound organelles  True nucleus  Sometimes multicellular - 6 eukaryotic Kingdoms:  Kingdom Opisthokonta  Kingdom Chromalveolata  Kingdom Archaeplastida o Kingdom Opisthokonta (Fungi):  Eukaryotic  Filamentous (hyphae in mycelium (body))  Do not photosynthesize (colourless)  Cell walls contain chitin  Heterotrophic  Sexual (fusion of mycelia) & asexual spores  Dikaryotic phase (n+n) – unique to fungi - Division Zygomycota - Division Ascomycota - Division Basidiomycota Polyphyletic – many phylogenies Spores – structures that are produced without the fusion of gametes Sporangium – structure that produces spores Plasmogamy – fusion of cytoplasm Karyogamy – fusion of nuclei Meiosis – reduction division Cladogram #2: Zygomycota Ascomycota Basidiomycota Asci Basidia Zygosporangia Conidia  Division Zygomycota:  Asexual sporangiospores  Sexual zygosporangia (-ium) - bread mould  Reproduction:  Division Ascomycota:  Asexual conidia (-ium)  Sexual asci (-us) - cup-shaped  Reproduction:  Division Basidiomycota:  Asexual conidia (-ium)  Sexual basidia (-ium) - mushroom  Reproduction: o Kingdom Chromalveolata (Brown Protista):  Eukaryotic  Unicellular or multicellular comprising of a thallus (with organs; body)  Autotrophic (chlorophyll a) or heterotrophic  Chlorophyll c BROWN  Fucoxanthin - Division Phaeophyta - Division Bacillariophyta - Division Dinophyta Cladogram #3: Bacillariophyta Phaeophyta Dinophyta Silicon cell walls Cingulum & sulcus (grooves) Multicellular Chlorophyll c Fucoxanthin  Division Phaeophyta:  Multicellular  Brown - brown seaweeds  Division Bacillariophyta:  Regular shapes - centric (round) - pennate (boat)  Cell walls made of silicon (glass) - diatoms  Division Dinophyta:  Specialised grooves (cingulum & sulcus) - dinoflagellates o Kingdom Archaeplastida (Red & Green Protista):  Eukaryotic  Unicellular or multicellular comprising of a thallus (with organs; body)  Autotrophic (chlorophyll a)  (primitive) Chloroplasts similar to those in plants - Division Rhodophyta - Division Chlorophyta - Division Charophyta Cladogram #4: Rhodophyta Chlorophyta Charophyta Plants Embryo Phragmoplast Chlorophyll b Primary endosymbiosis forms chloroplast  Division Rhodophyta:  Red pigments  Only chlorophyll a - Red algae  Division Chlorophyta:  Chlorophyll a & b - Green algae  Division Charophyta:  Phragmoplasts  Cellulose cell walls (sharp edges)  Store starch - Green algae with phragmoplasts - Move to land – ancestor  Branched  Chlorophyll a & b  Store starch  Phragmoplast  Protista reproduction: Spores – reproductive structures that do not fuse to give rise to the next generation Gametes – reproductive structures that must fuse in order to give rise to the next generation Sporangium – produce spores by meiosis Gametangium – produce gametes by mitosis Sporophyte – generation that produces spores in a sporangium by meiosis – diploid (2n) Gametophyte – generation that produces gametes in a gametangium by mitosis – haploid (n) - Alternation between generations (unique to protista)  Alternate at meiosis and syngamy  Sporophyte → mitosis → gametophyte → syngamy → sporophyte → ………   Rhodophyta (red algae) – only group that differs - Three generations (Triphasic); extra sporophyte generation Algae vs Embryophytes: - Algae:  Sporangia & gametangia are multicellular, each cell becomes reproductive (A & B) - Embryophytes:  Gametes & spores produced in a multicellular structure containing sterile cells (C & D)  Protect egg cells  Embryophyte reproduction (most of them): - Antheridium (male gametangium) - sperm (gamete) - Archegonium (female gametangium) - egg (gamete) - embryo – developing zygote; in archegonium o Kingdom Archaeplastida (Non-vascular plants):  Eukaryotic  Embryophytes (sterile layer of cells to protect spores & gametes)  No vascular tissue (no stems, no leaves, no roots)  Zygote retained by gametophyte - dominant gametophyte (long-lived and persistent) - dependent sporophyte  Dependant on water for reproduction - Division Anthocerotophyta - Division Hepatophyta - Division Bryophyta Cladogram #5: Anthocerotophyta Hepatophyta Bryophyta - Leptoids - Hydroids - Stomata on sporophyte Pores on - Multicellular rhizoids gametophyte - Loss of pyrenoid Charophyta - Cuticle (out group) Unicellular rhizoids Sterile layer of cells around reproductive organs  Division Anthocerotophyta:  Thallose gametophyte  Unicellular rhizoids  Single chloroplast has a pyrenoid  Pores on gametophyte (not stomata)  No cuticle - Hornworts  Division Hepatophyta:  Thallose/leafy gametophyte  Unicellular rhizoids  (In some) upper surface has a cuticle (wax layer; prevents water loss) - Liverworts  Division Bryophyta:  Leafy gametophyte  Multicellular rhizoids  Upper surface has a cuticle  Hydroids (transport water) & leptoids (tr. organic material)  Sporophytes have stomata - Mosses o Kingdom Archaeplastida (Seedless vascular plants):  Eukaryotic  Embryophytes (sterile layer of cells to protect spores & gametes)  Cuticle present  Stomata present  Vascular tissue (stems, leaves, roots) – xylem & phloem  Water required for fertilization - dominant sporophyte (long-lived and persistent) - independent gametophyte (thallose; require water to reproduce)  Spores: - durable cutinised walls - spores transported by wind instead of water  Lignin (adds strength) in cellulosic microfibrils  Some have vascular cambium - Division Lycopodiophyta - Division Pteridophyta Cladogram #6: Lycopodiophyta Pteridophyta Pith Sporangia in strobili Sori Microphylls Leaves Enations Megaphylls Enations Non-vascular plants (out group) Vascular tissue  Microphyll line: - Enations - Microphylls - Lateral sporangia  Megaphyll line: - Overtopping - Planation - Webbing = Psilotum (whisk ferns) - enations - simple vascular tissue - no pith - loss of roots = Equisetum - megaphylls - roots - pith  Division Lycopodiophyta:  Microphylls  Strobilus (-i)  Sporangia not covered  Roots  Stem has no pith  Reproduction:  Division Pteridophyta:  Megaphylls  Sorus (-i) (specialised cover; protests developing spores)  Leaves (with branching veins)  Pith - Ferns  Reproduction: Prothallus - dominant sporophyte & independent gametophyte - 2 generations look different - no chlorophyll in gametophyte – heterotrophic  Seed-plant reproduction (most of them):  Seed: (female) Three generations: 1. Parent sporophyte – contributes seedcoat/testa and sterile layer of cells around sporangium – megasporangium produces megaspores by meiosis (2n) (in ovule) 2. Offspring sporophyte – megaspore germinates to form megagametophyte 3. Parent gametophyte – megagametophyte produces egg by mitosis  Pollen: (male) o Kingdom Archaeplastida (Gymnosperms):  Eukaryotic  Embryophytes (sterile layer of cells to protect spores & gametes)  Plants with naked seeds (sperm = seed)  Vascular cambium (wood)  Seeds (ovule – developing seed)  Pollen – paternal structure that houses & protects male gametophyte – transported by wind - Division Pteridospermophyta - Division Cycadeoidophyta - Division Cycadophyta - Division Progymnospermophyta - Division Coniferophyta - Division Ginkgophyta - Division Gnetophyta Cladogram #7: Ginkgophyta Cycadophyta Coniferophyta Gnetophyta - vessels in wood Monoecious - male cone compound Broad dichotomously Compound veined leaves leaves - female cone compound - sperm loses flagellum Seedless vascular plants Cones Dioecious Seed Extinct – no living members of taxa Extant – currently living taxa Monoecious – both male and female reproductive organs in one individual Dioecious – male and female reproductive organs in separate individuals Cone – modified leaf that holds seed or structure that produces pollen  Division Pteridospermophyta: EXTINCT  Vascular cambium  Fern-like leaves  Wood with no vessels  Monoecious  Seeds on leaves - seedferns  Division Cycadeoidophyta: EXTINCT  Vascular cambium  Pinnately compound leaves  Wood with no vessels  Monoecious  Pollen come simple  Seed cone simple  Division Cycadophyta:  Vascular cambium  Pinnately compound leaves Wood with no vessels  Dioecious  Flagellated sperm  Pollen cone simple  Seed cone simple - Encephalarthos (e.g.)  Division Progymnospermophyta: EXTINCT  No seeds found  Division Coniferophyta:  Vascular cambium  Simple leaves (needle-like)  Wood with no vessels  Monoecious  Unflagellated sperm  Pollen cone simple (no bracts or axillary buds)  Seed cone compound ( has bracts and axillary buds) - Pinus - Widdringtonia - Podocarpus  Division Ginkgophyta:  Vascular cambium  Dichotomously veined broad leaves  Wood with no vessels  Dioecious  Flagellated sperm  No cones - Ginkgo biloba  Division Gnetophyta:  Vascular cambium  Leaved are varied  Wood with vessels  Dioecious  Unflagellated sperm  Pollen cone compound  Seed cone compound - Welwitschia - broad leaves with branched veins - Getum - no leaves; photosynthetic stems - Ephedra - two (shredded) leaves with basal meristem  Gymnosperm reproduction:  Ovule:  Pollen: (male) o Kingdom Archaeplastida (Angiosperms):  Eukaryotic  Embryophytes (sterile layer of cells to protect spores & gametes)  Plants with flowers  Seed-production in ovary (specialised set of leaves that have seeds)  Vascular cambium  Seeds  Pollen - Division Magnoliophyta ∽ basal angiosperms (primitive angiosperms) ∽ magnoliids ∽ eudicots ∽ monocots Cladogram #8: Basal angiosperms Magnoliids Monocots Eudicots Quadrimerous / Parallel veins pentamerous flowers Trimerous flowers (reduced # of repetitions) Gymnosperms - net veins - polymerous flowers (trimerous) Flowers  Monocots:  Dicots: Cotyledons One Two Floral parts 3X 4X / 5X Veins Parallel veins Netlike veins Pores in pollen Vascular bundles Roots ∽ Magnoliids:  Trimerous flowers (3X)  Pollen with one pore  Net-veined leaves ∽ Eudicots:  Quadri/pentamerous flowers (4/5X)  Pollen with three pores  Net-veined leaves ∽ Monocots:  Trimerous flowers (3X)  Pollen with one pore  Parallel-veined leaves  Angiosperm reproduction:  Ovary:  Flower:  Male gametophyte:  Megagametophyte: - Synergids release chemical compounds to attract pollen tube - Polar nuclei (n+n)  Microgametophyte: - Pollen grain extends pollen tube - 2 sperm nuclei: 1 fuses with egg 1 fuses with central cell → 3 n → grows into endosperm - Called double fertilisation  Domain Kingdom Division Clade Reason Bacteria - chlorophyll a (green) - peptidoglycans Cyanophyta - heterocyst in cell walls Archaea - ether lipids in cell membranes Opisthokonta Zygomycota - zygosporangia - chitin in cell Ascomycota - asci Walls Basidiomycota - basidia - brown Chromalveolata Phaeophyta - multicellular - brown Bacillariophyta - silicon cell walls - fucoxanthin - chlorophyll c - specialised grooves Dinophyta (cingulum & sulcus) Archaeplastida Rhodophyta - red pigments (Protista) Chlorophyta - green algae - lack of - green algae Fucoxanthin Charophyta - phragmoplasts - thallose gametophyte Anthocerotophyta - pores on gametophyte - pyrenoid (in chloroplast) - thallose/leafy gametophyte Archaeplastida Hepatophyta - cuticle (Non-vascular - leafy gametophyte plants) - cuticle Bryophyta - multicellular rhizoids Eukarya - stomata on sporophytes - multicellular - hydroids & leptoids - true nucleus - microphylls - membrane- Archaeplastida Lycopodiophyta - strobila bound organelles (Seedless vascular - megaphylls plants) Pteridophyta - sori - pinnately compound leaves Cycadophyta - pollen cone simple - seed cone simple - simple leaves (needle-like) Coniferophyta - pollen cone simple Archaeplastida - seed cone compound (Gymnosperms) - dichotomously veined broad Ginkgophyta leaves - no cones - wood with vessels Gnetophyta - pollen cone compound - seed cone compound - trimerous flowers Magnoliids - pollen with one pore - net-veined leaves - quadri/pentamerous flowers Archaeplastida Magnoliophyta Eudicots - pollen with three pores (Angiosperms) - net-veined leaves - trimerous flowers Monocots - pollen with one pore - parallel-veined leaves  Fungi: Zygomycota Ascomycota Basidiomycota Sexual structures Zygosporangia Asci Basidia Asexual structures Sporangiospores Conidia Conidia Non-vascular: Anthocerotophyta Hepatophyta Bryophyta Gametophyte Thallose Thallose/leafy Leafy Rhizoids Unicellular Unicellular Multicellular Cuticle on upper Cuticle on upper Cuticle None surface surface Hydroids & leptoids None None Contain Pyrenoid Contain None None Seedless vascular: Lycopodiophyta Pteridophyta Leaves Microphyll Megaphyll Sporangia location Strobili Sori Pith None Has pith Gymnosperms: Pteridospermo- Cycadeoido- Cycadophyta Coniferophyta Ginkgophyta Gnetophyta phyta phyta Extant/ Extinct Extinct Extant Extant Extant Extant extinct Broad & Dichotomously branched / Pinnately Pinnately Simple; Leaves Fern-like veined broad none / compound compound needle-like leaves 2 with basal meristem Wood No vessels No vessels No vessels No vessels No vessels Vessels Mono/di Monoecious Monoecious Dioecious Monoecious Dioecious Dioecious Pollen cone Pollen cone Pollen cone Pollen cone Seed/ No cones; simple simple simple compound pollen Seeds on leaves truly naked Seed cone Seed cone Seed cone Seed cone location seed simple simple compound compound Sperm Flagellated Unflagellated Flagellated Unflagellated Angiosperms: Magnoliids Eudicots Monocots Flowers Trimerous Quadri/pentamerous Trimerous Pollen One pore Three pores One pore Leaves Net-veined Net-veined Parallel-veined Adaptations Leading to a Terrestrial Environment: 1. Sterile layer of cells to protect spores & gametes 2. Pores on gametophyte 3. Unicellular rhizoids 4. Cuticle 5. Multicellular rhizoids 6. Hydroids & leptoids 7. Stomata 8. Vascular tissue 9. Spores with cutinised walls 10. Spores transported by wind 11. Vascular cambium 12. Lignin 13. Seeds 14. Pollen grains 15. Maternal protection (later paternal support also) Exam Questions: 1. Explain the advantage of a dominant sporophyte generation (phylogenetic advantage) 1 – One possible reason that stands out is that the sporophyte phase has an advantage over the gametophyte phase because it is diploid rather than haploid. Having two sets of genes can avoid expression of deleterious traits. The seed plant pattern of large sporophyte is a very effective system. Remember the key features: 1. Large sporophyte nurtures the tiny female gametophytes. 2. There are millions of tiny male gametophytes (pollen) that can be carried great distances, either by wind or by animals. 3. New sporophytes arise from very mobile, usually very tough, seeds that contain energy supply and tiny plant in suspended animation. 2 – Advantage of a dominant sporophyte was fertilization and dispersal of new/next generation timed with environmental conditions. 3 – Why sporophyte dominance? Many possible reasons, for example, (1) benefits of masking deleterious mutations in the diploid (sporophyte) phase, (2) greater variability of genetic expression, (3) truncation of gametophyte generation, with the vulnerabilities of requiring a medium for free-swimming sperm. ORIGINS: Science – observation & experiment  The Big Bang Theory: 1. The cosmos goes through a superfast inflation, expanding from the size of an atom to the size of a grapefruit in a tiny fraction of a second. ∞ small space + ∞ high energy (10-43 seconds) 2. Post inflation, the universe is a seething hot soup of electrons, quarks and other particles. (10-32 seconds, 1027 oC) 3. A rapidly cooling cosmos permits quarks to clump into protons and neutrons. (10-6 seconds, 1013 oC) 4. Still too hot to form into atoms, charged electrons and protons prevent light from shining: the universe is a superhot fog. (3 minutes, 108 oC) 5. Electrons combine with protons and neutrons to form atoms, mostly hydrogen and helium. Light can finally shine. (300 000 years, 104 oC) 6. Gravity makes hydrogen and helium gas coalesce to form the giant clouds that will become galaxies; smaller clumps of gas collapse to form the first stars. (1 billion years, -200 oC) 7. As galaxies cluster together under gravity, the first stars die (supernova) and spew heavy elements into space (> Fe) those will eventually turn into new stars and planets (attract lighter elements). (15 billion years, -270 oC) 8. The earth condenses with a core of Fe. Evidence: 1. Doppler effect: - blueshift (light moving closer) and redshift (light moving away) - stars further away, are moving away (red shift) - ∴ universe was compact 2. Background radiation: - even across universe; 2,726 K - ∴ thermonuclear explosion 3. Helium (He): - helium is 10% of universe - [He] is equal - known rate of release from stars (H → He); He from stars < 10% - ∴ 10% from nuclear explosion  Origin of Earth: - Earth had a H2 atmosphere - Gasses formed over a volatile earth ∽ H2S, NH3, CH4, H2O = reducing atmosphere ∽ Evidence in South Africa – FeS, PbS and ZnS are unstable in O2 - NH3 split to form N2 and H2 - H2O and CH4 formed CO and CO2 + H2  Origin of Cells: - Miller’s Experiment ∽ CO2 + H2 + electricity → organic molecules ∽ Organic molecules + heat → molecules polymerise → membrane ∽ Organic molecules + membrane → cell with genetic inheritance - Craig Venter’s artificial cell - First cell was heterotrophic/chemotrophic - First cell was in water (required for life)  Origin of Atmosphere: - Photosynthesis → O2 → oxidising atmosphere - O2 + UV → O3 - Ozone (protects) // UV radiation (destroy cellular life) → terrestrial life possible - Cyanobacteria form stromatolites → fossilise → date photosynthesis  Origin of Earth (cont.) - Terrestrial Earth has changed - Plate tectonics ∽ Floating continents ∽ Continental drift ∽ Subduction EVOLUTION: - Normal distribution - Species are not static; change with time - Life is variable (e.g.) ∽ Brassica oleracea ∽ Cotton seeds  Sources of Variation: - Mutation ∽ Change in nucleic acid (UV rays) - Sexual reproduction ∽ Produces new combinations - Gene flow ∽ Transfer of genes between populations - Genetic drift ∽ Chance changes in gene pools (big impact on small populations)  Modern Theory of Evolution: - Genetic inheritance - Natural selection - Speciation  Natural Selection: - Artificial Selection ∽ Humans deliberately changing the allele frequency of the gene pool ∽ Brassica oleracea - Survival of the fittest ∽ Fitness relates to reproduction ∽ 1859 – On the Origin of Species (Charles Darwin) - Evolution ∽ The gradual conversion of one species into one or several new species ∽ Only possible if - Individuals in a population are not all similar - Some individuals reproduce more successfully than others  - Natural Selection ∽ Populations increase exponentially ∽ Resources are limited, some offspring must die ∽ Offspring vary, best adapted survive and reproduce ∽ Accumulation of favourable traits, loss of unfavourable traits ∽ Environments change constantly ∽ Selection - Acts on existing alleles - Does not cause mutations - Operates in populations between individuals of same species - Does not operate in individuals  Speciation: - Species (almost impossible to define)  Morphological – look same  Biological – look identical; interbreed  Genetic – sequence genome  Palaeontological – fossils; cannot sequence genome  Evolutionary - Speciation  The process of creating a new species  Two organisms are considered members of different species if they do not produce fertile offspring when crossed - Phyletic speciation (directional)  When one species gradually becomes so changed that it must be considered a new species  Only type that maintains diversity - Stabilising speciation  Select against extremes  Reduction in variability - Divergent speciation  When one species gradually becomes so changed that it must be considered two new species MAJOR LINES OF EVOLUTION: Evidence for endosymbiosis:  New mitochondria and chloroplasts are formed are formed by binary fission, like bacteria  In Euglena, if the chloroplast is destroyed, it does not regenerate, it is autonomous  Inner membranes differ in composition to other organelles  Inner membrane is like that of prokaryotic cell membrane  Mitochondrial and plastid DNA are circular in shape  NA sequence analysis show portions nuclear of DNA came from plastids  Ribosomes of mitochondria and chloroplasts are 70s  Mitochondria have enzymes similar to those of prokaryotes  Plastids are present in very different algae, some of which are closely related to forms lacking plastids – suggests that if chloroplasts originated de novo, they did so multiple times  Most primitive algae have a peptidoglycan layer between their two membranes  Mitochondria and plastids are about same size as bacteria Move to land: - Charophyta  From sea  In shallow, freshwater ponds - branched - haplontic (mainly haploid) - chlorophyll a & b - store starch - phragmoplasts - First plant  Thallose - from ocean - through rivers - to fluvial wetlands - then aerial - liverworts - Approaches to desiccation  Avoid or tolerate - restrict ranges to moist habitats - dry out with dormant metabolism (non-vascular plants)  Protest - tracheophytes (vascular plants) Events diary: 1. Formation of universe 16 billon y.b.p (16 x 10 9) - Big Bang 2. Earth (4.6 x 109) - Condensation - Gravity 3. Cell (heterotroph) (3.8 x 109) - Organic matter - RNA - Bilayered vesicles in water 4. Photosynthesis (3 x 109) - Bacteriochlorophyll (> 700 nm) - Chlorophyll a (665 nm) - Cyanobacteria (oxygenic photosynthesis) - Evolved once 5. Nucleus (2 x 109) - Endosymbiosis (Archaea in Bacteria) - Eukaryotic cell (phagocytotic Archaea) hypotheses - Infection of Archaea by virus - Exomembrane concept 6. Mitochondria (proteobacteria) (same time as nucleus) - Second endosymbiotic event 7. Chloroplast (primary) (1.5 x 109) - Chloroplast with 2 membranes (cyanobacteria) - Secondary endosymbiosis - 3 (Dinophyta) - 4 (Heterokontophyta, Haptophyta) 8. Sexual Reproduction (1,2 x 109) - Origin - DNA repair - Conjugation hypotheses - “Cannibalism” - Maintenance - Creation of variety - Recombinational DNA repair during pairing 9. Multicellularity (Volvox) (1 x 109) - Aggregation of function-specific cells - Symbiosis of different species of cells - Multinucleate cells develop partitions hypotheses - Colony with incomplete cytokinesis - First in cyanobacteria - Occurred many times 10. Move to land (0.51 x 109) 11. Embryo (510 x 106) 12. Unicellular rhizoids 13. Stomata (450 x 106) 14. Multicellular rhizoids 15. Cutinised spores 16. Leptoids & hydroids 17. Cuticle (425 x 106) 18. Increased sporophyte (400 x 106) - Interpolation theory - New generation - Caused by mitotic division of zygote hypotheses - Transformation theory - A delay in the occurrence of meiosis after zygote germinated 19. Vascular tissue (400 x 106) - Xylem tracheids - Phloem 20. Enations 21. Microphylls (380 x 106) 22. Megaphylls (375 x 106) 23. Fern leaves (360 x 106) 24. Lignin (380 x 106) 25. Vascular cambium (380 x 106) 26. Seeds (359 x 106) 27. Vessels in wood (280 x 106) 28. Flowers, fruits, endosperm (250 x 106) (based on presence of oleane – only in flowering plants) - Oldest fossil = fruit (130 x 106) - Montsechia vidalii - Flowers - Basal Angiosperms (250 x 106) (Amborella trichpoda) - Magnoliids (140 x 106) - Monocots (125 x 106) - Eudicots (125 x 106) - Grasses (66 x 106) - Apetalous monocots (no petals)  Chlorophyta (1,5 x 109)  Multicellularity (1 x 109)  Rhodophyta (542 x 106)  Move to land (510 x 106)  Dinophyta (225 x 106)  Bacillariophyta (185 x 106)  Phaeophyta (150 x 106)