Ch. 7: Plant Growth and Reproduction

Terms• Biotic pollination: pollen carried animal--90%

flowering plants

Terms• Biotic pollination: pollen carried by animal--

90% flowering plants– Floral visitor: visits – Pollinator: deposits

Pollination as MutualismMutualism (+,+) interaction

– Plant gets pollen transferred– Animal gets “reward”

Reward?

Animal Rewards• Pollen: high protein• Also has lipids, minerals, starch

Renewable…

Rewards• Pollen renewed by:

– sequential anther dehiscence (multiple stamens)

Tony Danza’s Masters Study Creosote bush

Rewards– poricidal anthers (buzz pollination):

anthers have

Vaccinium (blueberry)

Rewards• Nectar:

(nectar glands: nectaries)

Who am I?

Rewards• Nectar: 10-60% sugars• Amino acids (butterfly

flowers)• Renewable!

Rewards• Oils/Resins:

– nest construction materials– “cologne” (male bee uses oil: )– larval food (Krameria)

Krameria wax gland: wasp food!

Pollination• Benefits animal pollination

– 1) Directed dispersal pollen: Gene flow!– Record distance?

Tropical orchid

Pollination• Benefits animal pollination

– Directed dispersal: aided by learning ( “handling time”)

– Fosters “floral constancy” (visit 1 sp )

Bumblebee visits to touch-me-not

Pollination• Benefits animal pollination

– 2) Style as “selective racetrack”– 1 pollen grain fertilize 1 ovule– Suppose 5 pollen grains arrive– How many fertilize an ovule? stigma

style

ovary

2 ovules

Pollen grains

Pollination• Benefits animal pollination

– 2) Style as “selective racetrack”– Pollen tubes 1N– If allele recessive, then

stigma

style

ovary

2 ovules

Pollen grains

Pollination• Benefits of animal pollination

– 2) Style as “selective racetrack”– Fittest (fastest) pollen grains

stigma

style

ovary

2 ovules

Pollen grains

Pollination• Style as “selective racetrack”• Ex., Coyote melon• Gourd in U.S. deserts.

Pollination• Style as “selective racetrack”• Study (2000) showed:

– 1) 900 grains: fully pollinate– 2) 1 visit 650 grains/flower. By 2 hr, >4000 deposited– 3) Over-pollinated: more vigorous seedlings

Outcrossing• Major benefit sexual reproduction: generate genetic

variation• by mating w/ others (outcrossing)

Why just enhanced?

Outcrossing

Why just enhanced?

Making gametes by meiosis: 23 pairs of chromosomesgives 8 million different combinations of Mom’s and Dad’s chromosomes in gametes

Outcrossing• Favor outcrossing:• 1) Dioecy

Outcrossing• Favor outcrossing:• 2) Floral morphology• Heterostyly: Diff. stamen/style lengths

– Distyly: 2 diff. “morphs” perfect flowers

Outcrossing• Ex, Gelsemium sempervirens

Outcrossing• Favor outcrossing:• 3) Floral phenology• Protandry: anthers • Protogyny: stigma

Protandry

Outcrossing• Favor outcrossing:• 4) Self-incompatibility: stop

Pollination syndromes

•Disclaimer: We make broad generalizations and exceptions exist to most statements!

• Pollination Syndrome: flower traits & pollinator traits that adapt each to other

Pollination syndromes• Bee pollination• Bees:

– intelligent, agile– Good sight (– good smellers

Leafcutter bee Bumble bee

Halictid bee

European honeybee

Pollination syndromes• Flowers:

– Colorful (not red)– Landing platform: place – Mildly fragrant– Often nectar guides: patterns

Petals in visible light(top) and UV (bottom)

Orchid flowerwith nectarguides (lines)on petals

Pollination syndromes• Fremontodendron decumbens

(endangered chaparral shrub) flowers

• UV reflectance photo (right)

Tony Danza??

Pollination syndromes• Beetle pollination• Beetles:

– Clumsy, dumb– Poor vision, good smellers

Pollination syndromes• Beetle pollination• Beetles:

– Clumsy, dumb– Poor vision, good smellers

• Flowers:– Lg (or lg inflorescences)– Lite color– Smelly

Pollination syndromes• Bird pollination:• Flower-visiting birds:

– Agile, long beak

– visual: see red

– poor “smell”

• Hummingbirds (native to Americas) hover

Pollination syndromes• Flowers:

– red/orange– Nectar (tube)– little – No

Aloe

???

Pollination syndromes• Butterfly pollination• Butterflies: good vision/smell, long tongue

– Don’t hover well

coiled tonguetongue extended

Pollination syndromes• Flowers:

– Color varies (blue, yellow, orange)– Landing – Nectar

Phloxpilosa

Pollination syndromes• Bat pollination

– Nocturnal: sight good (but it’s dark!)– Good – Agile

Pollination syndromes• Flowers

– Open night: light color– Lots– Fragrant– May be pendant

Parkia flowers

Pollination syndromes• Bat pollination: Mainly tropical• In U.S., saguaro

Saguaro flowers

Saguaro cactus