Transcript Pollination
Pollination Defn.? Pollination • Def’n: transfer pollen from stamen to stigma Carpel = pistil • Sporic meiosis: Life Cycle – Gametophytes make gametes BY MITOSIS – Sporophyte makes meiospores BY MEIOSIS • Two bodies/one cycle: alternation of generations Spore: cell grows into organism w/o joining with another cell • Overview: Life Cycle Life Cycle • Overview: • Fertilization: union sperm with egg to form zygote Floral variation • Parts may be fused – Like parts: connation (ex., petals to petals) – Unlike parts: adnation (ex., stamens to petals) Anisacanthus (Acanthaceae) flower Snapdragon flower Floral variation • Flower with stamens and pistil: perfect flower Another kind of perfection…. Floral variation • Some flowers imperfect. Pistillate or staminate Pistillate flowers Sagittaria Staminate flowers Sagittaria Floral variation • Pistillate & staminate flowers on separate individuals: Dioecy (MUST outcross) – Monoecy: both sexes on same individual. • Flower missing one or more sets parts: incomplete flower – All imperfect flowers incomplete! Who am I? Floral variation • Some flowers grouped: inflorescence – Special type: head. Ex, sunflower – Often: ray & disk flowers ray flowers disk flowers Pollination as Mutualism • Most flowers pollinated by animals • Exceptions: – wind pollinated (anemophily) – water pollinated (hydrophily) • Usually mutualism (+,+) – Plant: pollen transferred – Animal: “reward” Animal Reward… Rewards • Pollen: high protein – Also lipids, minerals, starch • Renewed by: – sequential anther dehiscence (multiple stamens) – poricidal anthers (buzz pollination) Rewards • Nectar: sugary fluid produced by nectaries – 10-60% mono- or disaccharides – amino acids too (butterfly flowers) • Renewable reward! Plant benefit? Pollination • Benefits animal pollination (to plant) – 1) Directed dispersal pollen: Floral cues and attractants – Learning decreases “handling time” – “Floral constancy:” visit single species on foraging trip Bumblebee visits to touch-me-not Pollination • Benefits of animal pollination – 2) Style as “selective racetrack” – 1 pollen grain fertilizes 1 ovule Pollen grains stigma style ovary 2 ovules Pollination • Benefits of animal pollination – 2) Style as “selective racetrack” – Pollen tubes – How many can fertilize an ovule? Pollen grains stigma pollen tubes style ovary 2 ovules Pollination • Benefits of animal pollination – 2) Style as “selective racetrack” – Pollen tubes haploid (1n) – 1 allele for every trait Pollen grains stigma style ovary 2 ovules Pollination • Benefits of animal pollination – 2) Style as “selective racetrack” – So, fittest (fastest) pollen grains mate Pollen grains stigma style ovary 2 ovules Pollination • Evidence? • Coyote melon: U.S. deserts – Seeds from over-pollinated flowers produce more vigorous seedlings Outcrossing • Major benefit sexual reproduction is ___________ • Enhanced by mating with others (outcrossing) How favor Outcrossing? Outcrossing • Favor outcrossing: • 1) Dioecy Outcrossing Favor outcrossing: • 2) Floral morphology • Heterostyly: Distyly and tristyly Outcrossing • • • • Favor outcrossing: 3) Floral phenology Protandry: anthers dehisce first Protogyny: stigma becomes receptive first Protandry Outcrossing • Favor outcrossing: • 4) Self-incompatibility: prevent germination self pollen or slow self pollen tube growth Pollinator Specialization • May be learned • May be species-specific – Monolecty: Flowers of 1 plant species visited – Oligolecty: Flowers of few plant species visited – Polylecty: Flowers of many plant species visited Pollination syndromes •Disclaimer: We make broad generalizations and exceptions exist to most statements! Pollination syndromes • Bee pollination • Bees: – – – – intelligent, agile good eyesight (including UV light) good smellers day-active Halictid bee Leafcutter bee Bumble bee Pollination syndromes • Bee flowers: – Colorful (not red) – Landing platform: where bee lands on flower – Often nectar guides: patterns help bee orient Petals in visible light (top) and UV (bottom) Pollination syndromes • Moth pollination • Moths: – – – – Poor vision (nocturnal) Excellent smellers Long coiled tongue Some (hawkmoths) hover Pollination syndromes • Moth pollination • Moth-pollinated flowers – – – – Open night Sweet fragrance White/light colored Nectar in tube • Nectar spur story Pollination syndromes • Angraecum orchid (Madagascar) Nectar spur almost 1 foot long! Pollination syndromes • Angraecum orchid from Madagascar. Nectar spur almost 1 foot long! Tongue… Pollination syndromes • Tongue Magazine, Gene Simmons fans. Family Guy: “Kiss saves Santa” Gene Simmons from KISS Biotic Pollination • Mutualism: (+,+) interaction • Do cheaters prosper?? • Sometimes….. Pollination syndromes • Flesh fly pollination • Lay eggs in meat Pollination syndromes • Some fly-pollinated flowers – No reward: flies fooled. Stapelia flower Pollination syndromes • Sexual mimics: Males attempt to mate (pseudocopulation) • No reward supplied A male wasp “mating” with an Ophrys flower (how embarrassing...) Pollination syndromes • Another trick flower • Grass pink orchid (Calopogon): pitcher plant bogs SE US • Fake stamens on labellum Cattleya orchid (flower made right side up) Calopogon orchid (flower made upside down!) Biotic Pollination • Do cheaters prosper?? Floral robbers! Cool robbers… Biotic Pollination • Floral Robber: Remove rewards (nectar, pollen) but do not pollinate • Ex, snapdragon • Is robbing bad for plant? Biotic Pollination • Do cheaters prosper?? • Yucca moth story • Yucca: Agave family – Ex, Yucca filamentosa Biotic Pollination • Pollination by yucca moth: Behavior • Question: What do you call a female yucca moth? Biotic Pollination • Question: What do you call a female yucca moth? • A pistil-packing momma………. Granny Glock Biotic Pollination • What if moth cheats (lays too many eggs?)