BIOL 112 1st Edition Lec-ture 14Outline of Last Lecture I. Phylogenetic TreesII. Early Animal EvolutionIII. Vendian Animal FossilsIV. “The Cambrian Explosion”V. What happened?VI.Hox Gene ClustersVII. Patterning GenesVIII. Phylum ChordataIX.Disagreement of SchemesOutline of Current LectureX. The “Crown Group”XI. Kingdom PlantaeXII. Plant EvolutionXIII. “Cryptogams”XIV. Phylum BryophytaXV. Advances of Bryophytes from AlgaeXVI. “Tracheophytes”XVII. Phylum PterophytaXVIII. Advances of Ferns over MossesXIX. Seed PlantsXX. GymnospermsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.XXI. Phylum ConiferophytaXXII. Male Cone and PollenXXIII. Female Cone and EggsXXIV. SeedXXV. Advances of Conifers over FernsXXVI. AngiospermsXXVII. Phylum AnthophytaXXVIII. Flower AnatomyXXIX. The OvuleCurrent LectureI. The “Crown Group•Three multicellular king-doms•K. Plantae•K. Fungi•K. Animalia•All true multicellular organ-isms (differentiated cells)with multi-tissue body plan•All make use of eukaryoticalternation of generationssexual cycleII. Kingdom Plantae•Multicellular, mostly macro-scopic, mostly autotrophic•Cell walls made up of cellulose•Multiple tissue/cell types organized into stereotyped structures: stems, leaves, & roots•Some members vascularized (xylem and phloem)•Most species terrestrial or secondarily aquatic (marine habitats)•At least 500,000 speciesIII. Plant Evolution•Appear to have descended from green algae approx 475 million yearsago•Candidate ancestors are charophyceans (advanced green algae): DNA, cell structure, biochemistry, and chlorophyll similarities to plants•Plant kingdom especially interactive•Comparison of primitive to advanced groups shows clear sequence ofevolutionary trends•This sequence is associated with increasing ability of the plants to live on dry lang, free from need for water film•From primitive (ancient) to advanced (derived) plant taxa — evolu-tionary trends:•Increasing complexity of organization of body•Increasing importance of the diploid phase of the life cycle and de-creasing importance to the haploid phase. This includes the ap-pearance of embryo sporophyte plants•Increasing independence from the need for free water film for fer-tilization and general life cycle•We emphasize the progressive differences•Comparisons and differences to discern to evolutionary trends from primitive to advanced phylaare as important as details ofeach representative life cycleIV. “Cryptogams”•Primitive phyla in K. Plantae•Do not produce seeds; mys-tery to early botanists howthese reproduced•We now know that these or-ganisms release microscopicspores which germinate intogametophytes•Informal category of cryptogams still applies to seedless plants (bryophytes, ferns, etc.)V. Phylum Bryophyta•Primitive phylum•Life in moist, marine environments, need water film•Haploid (gametophyte)-dominant life cycle; both gametophyte and sporophyte phases are multicellular•Poor multicellular organization, no vascularization of tissues•Males produce sperm in antheridia; females produce eggs in archego-nia•Sperm are poor swimmers and depend upon water splash to get to vicinity of archegonia•Sporophyte is non-photosynthetic and depends upon gametophyte for nourishment and supportVI. Advances of Bryophytes from Algae•Multicellular haploid and diploid stages — true alteration of genera-tions•One fertilization event leads to production of many haploid spores (many mitoses)•Problem for land existence:•Depends upon free water film for fertilization (sperm must swim)•Depends upon random physical event (water splash) to facilitate fertilization•Sporophyte is parasitic on gametophyteVII. “Tracheophytes”•“Plants with pipes” — Vascu-lar Plants•Have specialized tissues fortransport of fluids throughoutplant body: xylem andphloem •True xylem and phloem in-clude the unique complex polymer lignin•Advantage for living in drier environments, and also for supporting plant body farther from surface of earth•Specialized tissues for collecting water and nutrients: roots•Specialized tissues for connecting roots and leaves: stems•Sporophyte is only life cycle phase that is vascularized; gametophyte is never vascularizedVIII. Phylum Pterophyta•Ferns — seedless vascular plants•Mature fern is sporophyte (dominant phase of life cycle). Vascularizedwith true leaves and roots•On the underside of leaves, you can find the sori: collected sporangia•In each sporangium, meiosis produces haploid spores•Spore germinates into gametophyte; antheridia and archegonia de-velop on opposite sides of gametophyte thallus•After fertilization, sporophyte plant grows in place and eventually overgrows parent gametophyteIX. Advances of Ferns over Mosses•Greater use of sporophyte phase and reduction of gametophyte phase•Both phases photosynthetic; independent•Sporophyte is vascularized and larger; can live in dryer environments•But: fertilization still requires a water film for sperm, and gameto-phyte still needs very moist environmentX. Seed Plants•First forms possibly appeared near the end of the Devonian Period (~360 MYA)•Not common until after Permian Period (250 MYA)•Two evolutionary lineages:•Gymnosperms, “naked seeds”, conifers. Seeds produced on sporo-phylls, specialized leaf-derived structures, in cones•Angiosperms, “enclosed seeds”, flowering plants. Seeds produced inside ovaries, which eventually develop into fruitsXI. Gymnosperms•“Naked Seeds”, no fruit (ovary) around seed•4 phyla: pines, gingkos, cyads, gnetophytes•Most common phylum is the conifers: pines/junipers/redwoods/cy-press/firs•All phyla produce cones (strobili): highly modified leaves containing sporangia, sporophyllsXII. Phylum Coniferophyta•Sporophyte-dominant life cycle•Sporophyte is pine tree, vascularized form•Many live in cold northern climates•Needles: true vascularized leaves specialized to live in dry climates•“Evergreen” — each needle lives 2-7 years, but eventually dies•Sporangia collected into a cluster on cone: strobilus•Unlike ferns, separate kinds of spores: heterosporous•Microspores made in male strobilus•Megaspores made in female strobilusXIII. Male Cone and Pollen •Sporophyll: modified leaf — holds microsporangium•Sporangium: Sterile jacket