Lecture 2 - Pollination 2 Flashcards
Pollination Syndromes
Grouping of flower species (often from very different taxonomic groups) that have convergently evolved a particular suite of traits matched to attraction of and visitation by a particular kind of pollinator.
3 simple conditions are necessary for adaptive evolution:
1. variation among individuals in lifetime reproductive success
2. variation in heritable traits
3. a correlation between 1 and 2
What makes a good visit?
Behavioral factors
* Time of visit: after anther dehiscence (splitting of anther to reveal pollen) and coinciding with receptibe stigmas.
* Handling of flowers affects pollen pick-up and deposition
* Handling time per flower - affecting # of flowers visited per unit of time
* Pollinator speed and directionality affecting outcrossing distances (pollen dispersal)
* Not be too efficient at grooming off the pollen
* Flower constancy - the likelihood the next flower will be of the same species
Physical factors
* A good physical fitness in terms of size and shape to maximize contact with anthers
* Good surface structures: fur, hair, feather, scaly surfaces
Seeing UV light
Most pollinators can see light below 400 (at 300nm). They therfore see UV light.
Beetles
They are the largest order of insects making them important pollinators due to sheer numbers.
* 184 species are pollinated exclusively by beetles
* But pollinate 88% of flowering plants globally
The “dumb pollinators” !
Unspecialized mouth parts make them relatively destructive in their feeding on pollen.
They sometimes eat the entire flower-stamens, carpels and petals.
Use the flower as mating sites and commonly defectate there too.
Typical flower is relatively unspecilaized with little or no nectar.
Despite their destructiveness, they disperse moderate amounts of pollen reasonably well, moving several meters and up to 10 meters.
Best pollinating beetles have HAIRY BODIES.
Flies
Second only to bees as important pollinators: their numbers make up for their poor pollen carrying capacities.
Flies are not as hairy as bees and as efficient in carrying pollen, but pollinate nonetheless.
Mouth parts - mainly suctorial.
Proboscis (ranging from short to long) lined with a hydrophilic interior and capabale of regurgitating saliva.
Distance a challenge ~1 m, thus limited dispersal abilities.
Butterflies
Butterflies and moths represent ~10% of all insects.
Liquid feeders: sucking up nectar using a long coiled elastic proboscis.
Proboscis is filled with hemolymph, can allow it to coil and uncoil.
Less efficient than bees at moving pollen between plants. Highly perched their long thin legs, do no pick up much pollen on their bodies and lack specilaized structures for collecting it.
Butterflies one of the few insects that can see red, flowers often have long tubular (fused) corolla, with flaring part at end for a landing platform.
What a butterfly wants: sweet smell; lots of nectar, low viscosity; lots of adjacent flowers on inflorescence-to minimize energy expenditure in flight.
Moths
Similar to butterflies but flowers are dull or white and open nocturnally.
Compared to butterflies, they are better pollinators: wider bodies, shorter legs, hairier.
Hawkmoths
The most efficient pollinators in this order (lepidopteran).
Fly rapidly, hover expertly not requiring a landing pad.
Endothermic abilities thus, remain active in colder temperatures.
Decidedly furry!
Bees
Adult bees are more specilaized as pollinators than most other insects.
All bees have high energy needs that must be met for their survival.
Bees have endothermic abilities and therefore active at colder temperatures.
Many species feed their larvae exclusively from nectar and pollen-other pollinating insects (except butterflies/moths) have a much wider diet. Thus, the sheer number of visits made to flowers by bees is much greater than for any other taxon.
Flowers provide a landing platform with complex texture or ridging so that a bee can hang on easily. Copious nectar production.
The distance moved is also much greater- up to several km on a given foraging trip.
Feeding apparatuses also vary within this order.
Birds
Birds are very important pollinators of wildflowers throughout the world.
Old World tropics: Sunbirds
Hawaii: Honey creepers
New World: Hummingbirds
Australia: honeyeaters
Birds as pollinators long under appreciated as they are absent in Europe.
Flowers
* Often red with long narrow, fused corollas
* Usually scentless (birds cannot smell)
* Landing pads are unnecessary. They have very long tongues, and can hover;
* Ovary protected, often inferior
* Large amounts of nectar, low viscosity
* Large spatial separation between nectar supply and the anthers and stigmas
Bats
Flower large (easily seen), robust (so the bat can hold on), typically white (bats are nocturnal) with strong odours.
Flowers often appended to a trunk or large branch.
Flowers open at sunset; close at dawn.
Copious nectar production.
