Beetle covered with pollen on Magnolia http://farm1.static.flickr.com/151/436570953_91be748c40.jpg?v=0
HIGHER EVOLUTION PLANTS AND POLLINATORS
Bees – the Major Pollinator of Flowering Plants
Bees are adapted for feeding on nectar for energy and pollen for protein and other nutrients
Most pollen is used as food for larvae
Have a long proboscis – a complex “tongue” that enables them to obtain the nectar from flowers
Bees that are deliberately gathering pollen are more efficient pollinators
It is estimated that one third of the human food supply depends on insect pollination, most of which is accomplished by bees
Bees, like ants, are a specialized form of wasp
Change from predator to collecting pollen
“ The switch from insect prey to pollen may have resulted from the consumption of prey insects that were flower visitors and were partially covered with pollen when they were fed to the wasp larvae.” 2
2 ^ Poinar, G.O. Jr., Danforth, B.N. 2006. A fossil bee from early Cretaceous Burmese am 4. ber. Science 314: 614.
Which Came First?
But the bees and the flowers and other pollinators have all evolved –
Benefit of the flower
Dependent – very specialized
Examples of Co-evolution
Dependence - Yucca and moth
Gentian and Carpenter Bee – Floral sonication
Benefit to the flower; defenses against herbivores – Passionflower and Butterfly
Benefit to the flower – Mimicry and fakery – Orchid and bee
Mutual – Moth and orchid
Mutual – Ant and Acacia
Mutual – Fly and the Flower
Mutual – Columbines and shape shifts
Some are so dependent upon one another that were one to disappear, the other would very likely either starve or remain sterile.
This is Agraulis vanillae, the Gulf Fritillary. These butterflies are often present in large numbers, especially from mid-late summer. Gulf fritillary caterpillars are more often found on passion vines in open, full sun, and are usually found feeding on older leaves away from the tip of the vine.
These are the eggs and larva of the Zebra Longwing, Heliconius charitonius.
These butterflies lay their eggs in clusters at the very tip of the growing vine, and are more often found on plants that are at least partially shaded.
Thus, the two species of butterflies seem to avoid direct competition by feeding on different parts of the plants, and selecting different microhabitats.
In some Passiflora the stipules change to look like butterfly larvae
Egg Mimic Nectaries
Female butterfly egg laying and larval hatch is damaging to the Passiflora
One larvae can defoliate and entire juvenile plant or prevent seed formation by devouring the flowers
In order to avoid competition for food and cannibalism, Heliconius butterflies avoid plants that already have eggs on them Passiflora boenderi leaf with egg mimic nectaries . http://www.mobot.org/mobot/research/passiflora/subgenus_Decaloba.shtml Photo: J.M. MacDougal
These spots are “extrafloral” because they are found outside the flower
The nectar that passion vines secrete attracts ants, as sugar inevitably does.
The mercenary ants, in turn, are aggressive defenders of their food sources and will kill or drive off herbivores that would eat those sources.
Thus both parties benefit from the relationship
Visual Clues can be almost as important as chemical clues
Passion vines can escape by looking like other nearby plants
The camouflage pays off just often enough for the Passiflora to reproduce
There are approximately 20,000 flowers that need to be pollinated by vibrations
http://gears.tucson.ars.ag.gov/ic/buzzpol/buzzpol.html Here we see a small andrenid bee ( Protandrena mexicanorum ) perched atop a stamen of Buffalo Burr ( Solanum rostratrum ) follwing a vigorous bout of floral sonication.
DEEP COROLLA TUBES
Some plants have evolved flowers of extraordinary depth
This puzzled Darwin
He suggested that this was a response to a kind of ‘race’ with pollinating insects
The length of the tongues of pollinating insects could increase to increase nectar foraging efficiency
The Mediterranean orchid Ophrys speculum manufactures whiffs of the same scent that the female wasp Campsoscolia ciliata does.
The flower misleads male wasps into mating attempts that benefit the plant by spreading pollen
The orchids produce the fragrance more abundantly than female wasps do, and males prefer the stronger bouquet
With brushy red hairs, the Ophryrs speculum blooms look vaguely like the wasps that pollinate them.
Ophrys speculum Mirror Orchid In an extreme case of sex fakery, an orchid produces oddball chemicals that mimic a female wasp's allure so well that males prefer the floral scents to the real thing, scientists say.
ACACIA AND THE ANT MUTUALLY BENEFICIAL
Acacia and the Ant
Acacia’s defense against browsing animals are long, strong thorns.
Soon after the acacia grows a thorn a queen ant who has already mated lands upon it and gnaws a hole near the tip, just big enough to allow her to crawl into the hollow base.
There she lays her eggs
Bullhorn acacia and ant mutualism: thorn and extra-floral nectary, Costa Rica