Passive pollination
-wind/water
Animal pollination
-insects, mammals, and birds
Advantages of animal vs wind pollination
-increased pollination efficiency
-less pollen wasted
-lower dependence on abiotic conditions
-plants can succeed even at low density (high diversity)
why is self-pollination rare
-few plants are capable of self pollination
-some plants are capable of self-fertilization
-most plants are self-incompatible
importance of cross-pollination
-mixing of genetic material increases variability--increasing probability that some individuals will survive stressful events (climate) and providing variation for natural selection to act upon
-increases probability that unfavorable genetic traits are no
inbreeding depression
less favorable traits are expressed and less genetic diversity is available for natural selection to act upon
Enhancement of cross pollination
-production of pollinia
-dioecy and monoecy- separation of male and female plants or male and female flowers on the same plant
-temporal separation of sexes- protandry(dotted horse mint and passionvine): males mature first and protogyny (pawpapw and pipev
dioecious
-less common
-plants have only a unisexual flowers and all flowers on each plant are of the same sex
-holly, papaya, persimmon, kiwi, mulberyy, corn
monoecious
-more common
- plants have only unisexual flowers but have both male and female flowers on the same plant
-eggplants, pines, oaks, figs, cucumber, watermelon, pepper
Perfect flower/bisexual/hermaphroditic
-most common
-have both male and female parts in the same flower
-passionflower, lily, rose, apple, tomato, potato, strawberry, pear
Self incompatibility
-general terms that includes various genetic mechanisms that prevent self-fertilization, including preventing or halting:
-pollen germination, pollen tube growth, fertilization, embryo development
-end result: no seeds are produced
-this approach is an im
Economic value of insect pollination
-world-wide most food plants are wind pollinated or self fertilized
-30-35% of food in the USA is directly or indirectly dependent on insect pollinated plants
-honey bees contribute over 14 billion to the value of the US crop production
-some crops are 90
extent of insect pollination in the USA
-60 million devoted to crops that are largely self-pollinating but benefit from insect pollination (beans, cotton, peanuts, peas)
-40 million acres devoted to hay crops produced from bee-pollinated seeds
-6 million acres devoted to producing fruits, veget
California almond pollination in 2012
-1.5 million bee colonies pollinated 750,000 acres of almonds, producing 2 billion pounds of nutmeats
-on average, every colony pollinated 1333 lbs of nuts
-at a wholesale price of $2/lb, given approximately 14,000 bees in an 8-frame colony, each individu
Major pollinators in order of importance
-hymenoptera (bees, ants, wasps)
-diptera (flies)
-lepidoptera (moths and butterflies)
-coleoptera (beetles)
pollination constancy
some insects upon discovering that a particular flower has "rich rewards", tend to forage predominately at that type of flower
flower specialization
tubular shapes, trapping mechanisms, levered stamens, unusual fragrences, "buzz pollination", etc
floral attractants
-scent
-color
-shape
-nectar guides
-uv guides
floral rewards for pollinators
major- nectar and pollen
-minor- oils and waxes, perfumes
Coleoptera: beetles
-the earliest insect pollinators
-large, open, single flowers
-strong smell (good or bad)
-white or dull colored
-beetles feed on pollen, shelter inside blossom
-magnolias, poppies
Diptera: flies
-open, shallow, or tubular flowers
-pale or brightly colored
-mild or no smell, or carrion/dung smell
-flies feed on pollen, drink nectar
-Queen anne's lace, goldenrod, pipevines
lepidoptera: butterflies and moths
-butterflies: red and orange flowers, sweet smell
-mothsL pale color release scent at night
-nectar: high amino acid content
-flowers have long tubes or necks, limiting access to specific pollinators
-insects have elongate mouthparts, many need to perch t
hymenoptera: bees and wasps
-the most important
-feed on nectar and pollen, may collect pollen
-attractants: strong, sweet smell, visual cues (yellows, blues, purples, not red)
-flowering guide bees to reward- landing pads, UV guides
-flowers select for specific pollinators through:
orchid bees
-only males visit flowers of specific orchids
-volatile chemicals are stored on specialized structures
-pollinia attach to specific sites on bees during collection
-perfumes are specific chemical mixes that bees release at mating site