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Genomics and Non-‐Vascular Plants (8 Pts.)

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Genomics and Non-‐Vascular Plants (8 Pts.) Quiz 2 Genomics and Non-vascular plants (8 pts.) Today’s lecture review ques@on (2 pts) 1- (3 pts.) The authors of the Selaginella genome paper (a representave of an early vascular plant lineage) compared it to the genomes of a green alga, a moss and several flowering plants and calculated the number of gene families present at each evolu@onary transi@on. Their main findings are: A. The transi@on from aquac alga to land plant added the most gene families , followed by the origin of flowering plants. B. The transi@on from gametophyte-dominant (moss) to sporophyte-dominant (vascular plant) did not require as many new gene families as originally predicted. C. In addi@on to gains, gene family losses were also observed D. All of the above E. The transi@on to vascular plants needed the most new gene families, followed by the origin of flowering plants. F. None of the above. 2- (3 pts.) The synapomorphies mapped in the tree below are: 2 1 4 3 A. 1=dominant sporophyte , 2=pseudoelaters, 3=stomata, 4=oil bodies B. 1=stomata, 2=oil bodies, 3=dominant sporophyte , 4=pseudoelaters C. 1=oil bodies, 2=stomata, 3=pseudoelaters, 4=dominant sporophyte D. 1=pseudoelaters, 2=dominant sporophyte, 3=oil bodies, 4=stomata. For further study: think of alterna5ve synapomorphies for all lineages (include mosses, embryophytes and streptophytes (draw the missing branches in the tree) 3- (2 pts) Mechanisms of spore dispersal in mosses include: A. Ballis@c explosion of capsule in peat mosses B. “Salt-shaker” release using peristome teeth in hair cap mosses. C. Explosive dehiscence of capsule followed by vortex rings in peat moss D. B and C E. None of the above Innovaons of early (non-seed) vascular plants LYCOPHYTES Extant land plants charophytes mosses liverworts Gnetales angiosperms conifers ferns Ginkgo lycophytes hornworts cycads 8,500 10,000 100 1,200 12,000 300 1 90 700 300,000 seed plants vascular plants land plants Slide courtesy of Sarah Mathews. Vascular plant lineages LAND PLANTS NON-VASCULAR PLANTS Hepaticophyta (liverworts) Bryophyta (mosses) Anthocerophyta (hornworts) VASCULAR PLANTS SEEDLESS PLANTS Lycophyta (lycophytes) Psilotophyta (whisk ferns) Equisetophyta (horsetails) Pteridophyta (ferns) SEED PLANTS GYMNOSPERMS Cycadophyta (cycads) Ginkgophyta (ginkgo) ConifersRedwood group (junipers et al.) Pinophyta (pines et al.) Gnetophyta (gnetophytes) ANGIOSPERMS Anthophyta (angiosperms) Lycophytes were abundant and massive during the Carboniferous (~300mya) © 2005 Dennis C. Murphy. Vascular Plants (Tracheophytes): Synapomorphies • Sporophyte is dominant, becomes free living and long-lived, and is substan@ally larger than the gametophyte • Branched sporophyte– more capacity for photosynthesis and reproducon. • Fluid-conduc@ng (vascular) systems: xylem (water and minerals) and phloem (food transport) • Lignified secondary walls; added rigidity to plant organs and ssues • Differen@aon of sporophyte into shoot (true stem and leaves) and roots (with endodermis) Conduc@ve cells of vascular plants: Xylem and Phloem TREND: Lycophytes have Protosteles Cronk 2.15 Lycophytes have microphylls microphyll leaf trace stem long. section stem cross section leaf cross section Lycophyte sporophytes a c a. Isoetes b. Selaginella c. Lycopodium d. Huperzia b d Lycophyte Gametophytes under ground above ground dependent on symbiotic fungus photosynthetic hip://www.csupomona.edu/~jcclark/classes/bot125/resource/graphics/lyc_lycopodium_gametophyt.html Sporangia A B Angel Maden hip://www.arthurhaines.com/Florae_Novae_Angliae/Lycopodiaceae/Lycopodium-obscurum-strobilus.jpg Heterospory has evolved within Lycophytes Homosporous = one type of sporangium produces one type of spore, which produces a bisexual gametophyte. - Lycopodiaceae (Huperzia, Lycopodium) George Shepherd Heterosporous = two types of sporangia (micro- and megasporangium) produce two types of spores (micro- and megaspores), which produce male (micro-) and female (mega-) gametophytes, respec@vely. - Isoetes, Selaginella hip://www.botany.hawaii.edu/faculty/webb/BOT311/BOT311-00/LycoRepro/LycoRepro-1.htm hip://[email protected]/Resources/Botany/Lycophytes/ TREND: Homospory to Heterospory Heterospory evolved independently in ____________, ____________and___________ Selaginella Selaginella Life Cycle Isoetes hip://www.plantsystemacs.org/users/robbin/10_6_05/upload98/Isoetes_lithophila.JPG Isoetes Gametophytes hip://www.plantsystemacs.org/imgs/robbin/r/Isoetaceae_Isoetes_riparia_36071.html hip://www.plantsystemacs.org/imgs/robbin/r/ Isoetaceae_Isoetes_riparia_36073.html Unique Features of Lycophytes • Sporophytes: – Leaves are microphylls – Dichotomous branching (from apical meristem) in stems and roots – Stem and roots have protosteles – Primary root system is lost; advenAous roots originate from inside stem (from the pericycle) – Sporangia are associated with leaves called sporophylls; organized into a strobilus (cone) or concentrated on areas of the stem. • Gametophyte: – minute, photosynthe@c or not, oren associated with fungus; may have rhizoids – bisexual with antheridia and archegonia (in homosporous lycophytes) or unisexual and endosporic (heterosporous lycophytes) Clicker review ques@on (2 pts.) Synapomorphies of vascular plants include: A. A dominant sporophyte generaon B. Heterospory C. Xylem and phloem D. Differen@aon of stems, leaves and roots E. Stomata F. Vessel elements and sieve tube elements Vocabulary Tracheids, vessel elements Sieve cell, sieve tube member Stele, protostele Microphyll Sporophyll Strobilus/ strobili Dichotomous branching Endodermis, pericycle Adven@@ous roots Heterospory: microsporangia (microspores, microgametophytes), megasporangia (megaspores, megagametophytes) Endosporic gametophyte .
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