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Plant Reproductive Biology Michael G. Simpson

Plant Reproductive Biology Michael G. Simpson. What is it? Study of sexual and asexual reproduction Pollination mechanisms Gene flow Genetic variation Propagule dispersal Why study it? Insight into adaptive significance & homology of systematic characters

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Plant Reproductive Biology Michael G. Simpson

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  1. Plant Reproductive BiologyMichael G. Simpson What is it? Study of sexual and asexual reproduction Pollination mechanisms Gene flow Genetic variation Propagule dispersal Why study it? Insight into adaptive significance & homology of systematic characters Insight into delimitation of species and subspecies.

  2. Sexual Reproduction Non-seed plants Seed plants: Pollination - transfer of pollen from microsporangia to stigma (angiosperms) or ovule (gymnosperms) Wind pollination - ancestral (all gymnosperms) Animal pollination - derived for angiosperms Some angiosperms secondarily wind pollinated Fertilization - fusion of sperm and egg ––> embryo (new sporophyte)

  3. Strategy of animal pollination:Attractant & Reward Attractant Visual perianth stamens (e.g., Myrtaceae, Mimosoideae) staminodes (e.g., Zingiberaceae, Cannaceae) corona (e.g., Narcissus) inflorescence Olfactory - usu. from perianth sweet rotten (foul/fetid) - e.g., fly pollinated flowers

  4. Strategy of animal pollination:Attractant & Reward Reward Nectar Pollen Waxes Resins or “Trick” instead of a “Treat” Insect trapped (Aristolochia) or drowned (Nymphaea sp.) Mimicry E.g., fooling male insect into “mating” with orchid

  5. Pollination Mechanisms INSECT (entomophily) Bees (melittophily/hymenopterophyly): fls. showy, colorful, fragrant, with: nectar guides landing platforms Butterflies (psychophily): fls showy, colorful, fragrant no nectar guides long tubes or spurs

  6. Pollination Mechanisms Moths (phalaenophily): large, white, fragrant no nectar guides usually tubes or spurs

  7. Pollination Mechanisms Flies (sapromyiophily) maroon / brown in color foul smelling (like rotting flesh)

  8. Pollination Mechanisms Birds (ornithophily): red (often, not always) tubular (often)

  9. Pollination Mechanisms Bats (cheiropterophily): nocturnal anthesis large, colorful or white produce copious nectar or pollen

  10. Pollination Mechanisms Wind (anemophily): flowers small, numerous, often unisexual perianth absent or non-showy flowers often produced in mass

  11. Pollination Mechanisms Water (hydrophily):

  12. Breeding systems Outbreeding versus Inbreeding vs. in-between

  13. Breeding systems Outbreeding = outcrossing / allogamy / xenogamy: How is it promoted? 1) Plant sex: dioecy (incl. gynodioecy, androdioecy, trioecy)

  14. Breeding systems Outbreeding = outcrossing / allogamy / xenogamy: 2) Difference in timing of floral parts = dichogamy protandry - male first protogyny - female first

  15. Breeding systems Outbreeding = outcrossing / allogamy / xenogamy: 3) Spatial separation of anthers and stigmas = hercogamy heterostyly: different style/stigma & correlated anther heights

  16. Outbreeding = outcrossing / allogamy / xenogamy: 3) Spatial separation of anthers and stigmas = hercogamy enantiostyly: left & right-handed flowers

  17. Outbreeding = outcrossing / allogamy / xenogamy: 3) Spatial separation of anthers and stigmas = hercogamy movement hercogamy: trigger mechanisms

  18. Outbreeding = outcrossing / allogamy / xenogamy: 3) Spatial separation of anthers and stigmas = hercogamy movement hercogamy: e.g., stigma movement Diplacus [Mimulus] aurantiacus (Phyrmaceae)

  19. Folding of style best explained as adaptation to reduce interference in bird pollination

  20. Outbreeding = outcrossing / allogamy / xenogamy:4) Self-incompatibility Genetically determined, inability for fertilization to occur between gametes derived from one individual.

  21. Inbreeding = selfing autogamy (w/in 1 flower) & geitonogamy (between fls. of 1 indiv.) Selective advantage: ensures propagule production Disadvantage: reduced to absent genetic variability allautogamy: both outcrossing & inbreeding e.g., Viola, Clarkia: two flower types: chasmogamous flowers - normal, open cleistogamous flowers - remain closed

  22. Fruit/seed dispersal Wind - samaras, winged seeds Water - e. g., Cocos nucifera (Arecaceae) Explosive dehiscence Self (Autochory, e. g., Arachis hypogaea) Animal

  23. Asexual Reproduction Vegetative reproduction: ramets Rhizomes Bulbs, bulbels Corms, cormels Plantlets

  24. Asexual Reproduction Agamospermy - seed production without fertilization Parthenogenesis (diploid egg) Adventive polyembryony (non-egg diploid cell)

  25. Hybridization in plants

  26. Polyploidy – evolution of multiple sets of chromosomes; major mechanism of speciation.

  27. Hybridization in plants Common Can produce sterile, vegetatively reproducing species (e. g., certain cacti)

  28. Testing for breeding mechanisms A B C D 1) Control + + + + 2) Caged, self-pollinated - + + + 3) Caged, left alone - - + + 4) Emasculated, caged - - - + 5) Caged, emascul., outcrossed + + + + What is the breeding mechanisms for species A, B, C, D?

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