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Plant Reproductive BiologyMichael 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 Insight into delimitation of species an subspecies.

Sexual Reproduction: 

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)

Strategy of animal pollination:Attractant & Reward: 

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) - e.g., fly pollinated flowers

Strategy of animal pollination:Attractant & Reward: 

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

Pollination Mechanisms: 

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

Pollination Mechanisms: 

Pollination Mechanisms Moths: large, white, fragrant no nectar guides usually tubes or spurs

Pollination Mechanisms: 

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

Pollination Mechanisms: 

Pollination Mechanisms Birds (ornithophily): red (often) tubular

Pollination Mechanisms: 

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

Pollination Mechanisms: 

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

Pollination Mechanisms: 

Pollination Mechanisms Water (hydrophily):

Breeding systems: 

Breeding systems Outbreeding versus Inbreeding vs. in-between

Breeding systems: 

Breeding systems Outbreeding = outcrossing / allogamy / xenogamy: 1) Plant sex: dioecy (incl. gynodioecy, androdioecy, trioecy)

Breeding systems: 

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

Breeding systems: 

Breeding systems Outbreeding = outcrossing / allogamy / xenogamy: 3) Spatial separation of anthers and stigmas = hercogamy

enantiostyly: left & right-handed flowers: 

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

movement hercogamy: trigger mechanisms: 

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

movement hercogamy: e.g., stigma movement: 

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

Outbreeding = outcrossing / allogamy / xenogamy:4) Self-incompatibility: 

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

Inbreeding = selfing: 

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

Fruit/seed dispersal: 

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

Asexual Reproduction: 

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

Asexual Reproduction: 

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

Hybridization in plants: 

Hybridization in plants

Hybridization in plants: 

Hybridization in plants Common Polyploidy - major mechanism of speciation Can produce sterile, vegetatively reproducing species (e. g., certain cacti)

Testing for breeding mechanisms: 

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 + + + +