Bis2CF10.Lecture20

Bis2CF10.Lecture20 - Lecture 20 INTRODUCTION TO ANGIOSPERMS...

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Unformatted text preview: Lecture 20 INTRODUCTION TO ANGIOSPERMS Last: evolution and diversity of gymnosperms Basic features, synapomorphies of angiosperms (see Chapters 34 & 38 for details) Possible angiosperm outgroups Rooting the angiosperm tree Next: evolution and diversity within angiosperms ANGIOSPERMS = FLOWERING PLANTS Lemna (duckweed) Drimys Cactaceae Angiosperms abundant: 100 MY Oldest fossil angiosperms Early Cretaceous, 135 MY First seed plants (seed ferns) Late Devonian, 365 MY First land plant spores Middle Ordovician, 470 MY Angiosperms abundant: 100 MY Oldest fossil angiosperms Early Cretaceous, 135 MY Jurassic landscape Cretaceous leaf & pollen sequence (Potomac Formation, Maryland & Virginia) STAGES Cenomanian LATE CRETACEOUS EARLY CRETACEOUS 98 MY Albian tricolpate Aptian 125 MY Barremian monosulcate Archaefructus NE China OUTGROUPS SISTER GROUP ANGIOSPERMS Reconstructing most recent common ancestor Reconstructing precursors of angiosperm structures Simple leaves = Heterospory Nonmotile sperm naked seeds (also no flowers) Opposite leaves Vessels Secondary growth Net-veined leaves 2+2 microsporangia Carpel: ovules enclosed Two integuments Reduced gametophytes Double fertilization CARPEL seeds enclosed Net-veined leaf (reticulate veins) Several vein orders Midvein Ginkgo Cycad 125 MY Ficus perforations Conifer: tracheids Angiosperm: vessels & fibers Winteraceae Drimys vesselless wood anther cross-section Carpel megasporophyll Stamen microsporophyll sepals + petals = perianth = floral axis anther cross-section Carpel megasporophyll Stamen microsporophyll = floral axis Three fused carpels Magnolia: “strobilar” bisexual flowers “Leaf-like”carpels (Winteraceae) carpel stamen sepals + petals = perianth floral axis “Leaf-like” stamens carpel stamen sepals + petals = perianth floral axis Ovule with two integuments, bent back Male gametophyte development carpel stamen sperm tube nucleus sepals + petals = perianth floral axis synergids egg zygote polar nuclei antipodals Female gametophyte development & double fertilization Ovule with two integuments, bent back Male gametophyte development carpel stamen sperm tube nucleus sepals + petals = perianth floral axis synergids egg zygote embryo polar nuclei antipodals triploid Female gametophyte development & double fertilization TRIPLOID (3n) Simple leaves = Heterospory Nonmotile sperm naked seeds (also no flowers) Opposite leaves Vessels Secondary growth Net-veined leaves 2+2 microsporangia Carpel: ovules enclosed Two integuments Reduced gametophytes Double fertilization Nonmotile sperm CARPEL seeds enclosed GNETOPHYTES Ephedra Fagales male strobili Gnetum Quercus Richard von Wettstein male female BENNETTITALES Williamsonia Jurassic Early Cretaceous Magnolia BENNETTITALES Williamsonia Jurassic Early Cretaceous Bisexual “flowers” Crane 1985 Carboniferous seed ferns Conifers & relatives (Sir) Peter Crane Gnetophytes ANTHOPHYTES Crane 1985 Bennettitales Williamsoniella Gnetophytes male Welwitschia Angiosperm Berberis Gnetophytes flower carpel Williamsonia ANTHOPHYTES Chaw et al. 2000 18S rDNA, rbcL, mtSSU rDNA Angiosperms “Gnepine” hypothesis Conifers Gnetophytes Pinaceae Caytonia: Jurassic cupule Angiosperm ovule with two integuments, reflexed Elkinsia Lyginopteris Medullosans Taxaceae Cephalotaxus Taxodiaceae Araucariac Podocarpac Pinaceae Ephedra Welwitschia Gnetum Emporia Ginkgoales Cordaitales Corystosperms Morphology with molecular backbone GNET Caytonia Status 8 steps Dollo Doyle 2008 CONIFERS One ofossil living living fossil Autunia Peltaspermum Callistophyton Cycadales Glossopterids Pentoxylon Bennettitales Caytonia Amborella Nymphaeales Hydatellaceae Schisandrac Illicium Trimenia Austrobaileya Chloranthac Winteraceae Asaroideae Saururaceae ANGIOSPERMS OUTGROUPS SISTER GROUP ANGIOSPERMS Reconstructing most recent common ancestor Reconstructing precursors of angiosperm structures Sorry, much too hard… Qiu et al. 1999 18S nrDNA, rbcL, atpB, atp1, matR EUDICOTS Laurales Magnoliales MAGNOLIIDS Piperales Canellales Chloranthaceae Yin-Long Qiu MONOCOTS Ceratophyllum ROOT “ANITA lines” Amborella OUTGROUPS Nymphaeales: herbaceous aquatics Amborella Nymphaea: water lily Cabomba (Nymphaeales) Austrobaileyales Illicium: star anise ROOT “ANITA lines” Amborella OUTGROUPS ...
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This note was uploaded on 04/19/2011 for the course BIOLOGY BIS 2C taught by Professor Doyle during the Fall '10 term at UC Davis.

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