Angiosperm Evolution - PowerPoint PPT Presentation

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Angiosperm Evolution

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  1. Angiosperm Evolution Chapter 6 Simpson, 2nd Edition

  2. Vascular tissue Earth Forms Prokaryotic Cells Eukaryotic Cells Multicellular Plants Flowers 5,000 mya 4,000 mya 3,000 mya 2,000 mya 1,000 mya Seeds Major Evolutionary Advances • Life - 3,800 mya • Prokaryotic cell/autotrophic 1. Earth 2. Prokaryotes 3. Eukaryotes 4. Multicellular life 5. Vascular tissue 6. Seeds 7. Flowers Flowers– 130 mya Eukaryotic cell - 1,400 mya Multicellar plants - 1,000 mya • Vascular tissue - 430 mya • Needed on land - why? Seeds - 350 mya

  3. Timeline • Devonian Period • 400mya – 1stvascplts • Psilotum – like • Devonian-Carboniferous • ferns, lycophytes, sphenophytes & progymnosperms • Mesozoic • gymnosperm-dominant seed plants • Cretaceous Period • 130 mya 1stfossil flowers • 90 mya - worldwide angiosperm dominance

  4. Relationships of Angiosperms Bennettitales and Genetophytes – 225 mya

  5. Relationships of Angiosperms

  6. Systematics • phylogeny represented by cladogram (phylogenetic tree • branching diagram that conceptually represent the evolutionary pattern of descent • lines represent lineages, with implied time scale • branch = divergence • ancestral = preexisting • apomorphy= derived (evolutionary novelty)

  7. Systematics • Phylogenetic Systematics (cladistics) • methodology to infer evolutionary history using apomorphies • recognizes monophyletic groups (= clade) • Phylogenetic Classification Schemecan result • avoids: • paraphyletic groups • com anc but not all descendants • polyphyletic groups • two or more sep groups with sepanc

  8. Angiosperm Systematics What conclusions can be drawn from this cladogram?

  9. Angiosperm Apomorphies flower, usually with perianth

  10. Angiosperm Apomorphies stamens with 2 lateral thecae, each composed of 2 microsporangia reduced, 3-nucleate male gametophyte

  11. Angiosperm Apomorphies • carpels and fruit formation • conduplicate(inwardly folded longitudinally & along the central margin) megasporophyll bearing 2 adaxial rows of ovules • carpel body encloses seed (angiosperm name origin)

  12. Angiosperm Apomorphies • ovules with 2 integuments • bitegmic with micropyle at distal end

  13. Angiosperm Apomorphies reduced, 8-nucleate female gametophyte

  14. Angiosperm Apomorphies • reduced, 8-nucleate female gametophyte: • evolution of female gametophyte

  15. Angiosperm Apomorphies • endosperm formation • product of double fertilization • zygote = 1 sperm + egg • endosperm = 1 sperm + polar nuclei

  16. Angiosperm Apomorphies • sieve tube members • sieve plates – contain pores at end walls larger than lateral pores • sieve cells are primitive sugar-conducting cells vessels found in all but primitive angiosperms

  17. Origin of Angiosperms Archaefructus130 mya northern China reconstruction of Archaefructussinensis fossil imprint of Archaefructuslianogensis

  18. Four evolutionary trends among flowers • floral parts many -> few • floral whorls from 4, long floral axis, separate parts -> reduced whorls, short floral axis, fused parts • superior -> inferior ovary • symmetry radial -> bilateral

  19. Lonicera (honeysuckle) Nelumbo (Lotus) Vanilla (vanilla bean orchid) • floral parts few • reduced whorls, short floral axis, fused parts • inferior ovary • bilateral symmetry Helianthus disk floret Anemone

  20. Order Asterales Asteraceae(=Compositae) Sunflower Family 1620 genera 23,600 species • most diverse dicot family • 98% herbaceous, but shrubs, trees or vines also • inflorescence a head, subtended by involucre of phyllaries • K0-∞C(5) [4] or (3) A(5) [(4)] G(2) inferior

  21. p. 429 Fig. 8.131 Order Asterales Asteraceae(=Compositae) Sunflower Family 1620 genera 23,600 species

  22. p. 430 Fig. 8.132 Order Asterales Asteraceae(=Compositae) Sunflower Family 1620 genera 23,600 species

  23. p. 431 Fig. 8.133 Order Asterales Asteraceae(=Compositae) Sunflower Family 1620 genera 23,600 species

  24. p. 432 Fig. 8.132 Order Asterales Asteraceae(=Compositae) Sunflower Family 1620 genera 23,600 species