BIO SCI 152 1st Edition Lecture 10Plant Diversity I Evolution and non-vascular plants: Green Algae to BryophytesLearning objectivesAfter Suitable revision, you should be able to- Name common features between plants and their algal ancestors - Understand limitations to moving onto land and name new innovations in evolution ofplants for adaptation to living on land (i.e. plant characteristics NOT found in algal ancestors) - Explain the key ideas of life cycles and define the associated terms (below) - Know the difference between haploid-dominant, diploid-dominant and alternation ofgeneration forms of life cycle and key examples of plants which use each. Vascular ZygoteVocabularyStomata GameteCuticle GametangiumEvolutionLignin ArchegoniumFossil AntheridiaAlgaeSporopollenin BryophytePhylogenyDiploid fernCharaHaploid GymnospermProtistSyngamy AngiospermChlorophyllMeiosis LiverwortCarotenoidMitosisHornwort – AnthoceraCellulose cell wallSporophyteRhizoidGametophyteOxygen Accumulation in Earth’s AtmospherePrehistory of Land Plants (fossil evidence)Precambrian (> 550 millions of years ago)• Prokaryotic cyanobacteria - first photosynthesis ~3,000 million yearsago (increasing O2 in atmosphere) • Evolution of eukaryotes – endosymbiosis : cyanobacteria + bacteria = primitiveprotists > 1500 myaPrehistory of Land Plants(fossil evidence) Fig. 30.8Precambrian - Paleozoic• Algal protists diversify 1000 - 600 mya • First green algae 750 – 700 mya • First plants 490 – 438 mya • Colonization of land by plants ~ 470 mya o (First terrestrial vertebrates 370 mya)•Phylogenetic ?• Phylogeny : • Gk. Phyllos – ‘Tribe’, from Genesis - origin • evolutionary origins based on fossil evidence,anatomical similarities, gene sequences • Phylogenetic ‘tree’ – (like a family tree)estimated evolutionary relationships Fig. 21.1 Phylogenetic Tree – evolutionary origin ofLand PlantsPlants are the first truly terrestrial organismsGreen algae closest relativesFreshwater green algae Chara – direct ancestor of Land plantsOrigin of Land Plants from a green algal ancestorKey features shared by green algae and land plants• Cellulose cell wall • Starch as carbohydrate storage form • Chlorophylls a and b, and beta-carotene • Similarities in mechanisms of mitosis and cytokinesis (cell division) • Similarities in sperm ultrastructure • Molecular data – gene sequence similarity • Similarities in life cycles Challenges to moving onto land?In class exercise• Cuticle is for …? • Rhizoids are for….? • Primitive vasculature and leaves • Aerial component needs…..? • Control of gas exchange - stomata Prehistory of Land Plants (fossil evidence)Life Cycles in PlantsGeneralized life cycle Fig. 21.4Figs 15.9, 15.12, 15.4 – Mitosis andMeiosis – review from BIOSCI 150!!Generalized life cycleHaploid Dominant Life cycle, Diploid Dominant Life cycle, alternation of generation =haploid and Diploid co-dominantPlant Life Cycles SummarizedEvolution towards sporophyte-dominantNon-vascular plantsBryophytes – non vascular plants• Three Divisions : - Bryophytes (Mosses), Liverworts and Hornworts • Moist and wet habitats, lack true leaves • Liverworts and hornworts - totally nonvascular, mosses – some limitedvasculature • Need water to complete the life cycle • No woody tissue for support Mosses >12,000 speciesGrow together to form dense mats Dense growth helps water retentionRhizoids attach plant to substrate Have stem and leaf-like structuresLife cycle with noticeable green gametophyteMosses - Haploid dominant Life cycle Figure 21.6Hepatophyta - LiverwortsLiverwort gametophytes and sporophytesReproduce with gemmae cupsAnthocera – Hornworts Fig. 29.5100 speciesSimilar in appearance to liverwortsSporophytes are elongated capsules growing out of gametophytesPractice Exam Question in ClassBryophytes restricted to moist habitats• Summary • Plants evolved from (aquatic) algal ancestors • Plants and green algae still share key features • For success invasion onto land, plants had to evolve structural support,vascular system (lignin support), desiccation resistance (cuticle, stomata) • Generalized life cycle – alternation of generation – haploid or diploid dominant.(Key examples mosses, ferns) • Plant evolution can be seen in existing plants: non-vascular plants are part-way between algae and vascular plants – mosses, liverworts,