Chapter 6 Simpson, 2nd Edition Angiosperm Evolution Chapter 6 Simpson, 2nd Edition

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 Eukaryotic cell - 1,400 mya Multicellar plants - 1,000 mya Vascular tissue - 430 mya Needed on land - why? Seeds - 350 mya Flowers – 130 mya Earth Forms Prokaryotic Cells Eukaryotic Cells Multicellular Plants Vascular tissue Flowers 5,000 mya 4,000 3,000 2,000 1,000 Seeds

Timeline Devonian Period Devonian-Carboniferous Mesozoic 400mya – 1st vasc plts Psilotum – like Devonian-Carboniferous ferns, lycophytes, sphenophytes & progymnosperms Mesozoic gymnosperm-dominant seed plants Cretaceous Period 130 mya 1st fossil flowers 90 mya - worldwide angiosperm dominance

Relationships of Angiosperms Bennettitales and Genetophytes – 225 mya

Relationships of Angiosperms

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)

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

Angiosperm Systematics What conclusions can be drawn from this cladogram?

Angiosperm Apomorphies flower, usually with perianth

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

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)

Angiosperm Apomorphies ovules with 2 integuments bitegmic with micropyle at distal end

Angiosperm Apomorphies reduced, 8-nucleate female gametophyte

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

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

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

Origin of Angiosperms Archaefructus 130 mya northern China reconstruction of Archaefructus sinensis fossil imprint of Archaefructus lianogensis

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

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

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 K 0-∞ C (5) [4] or (3) A (5) [(4)] G (2) inferior

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

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

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

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