Saturday, October 03, 2009

Economics of Nature

Friend Bryan Buckley once told me a great econ story about how plants are green because it's the hardest color to absorb. Plants work on the margin and absorb all colors except for green. Here's another great example of how even nature is subject to the same laws of economics (selfishness is good and trading partners have to be honest):
The congruence between the behavior of flowers and their pollinators has led students of pollination ecology to speak of the "harmony" between the two groups. But if such harmony exists it is purely of a self-serving sort. The bats are interested only in filling their stomachs, and it is no concern of theirs that they may be doing a favor for the plant. Indeed, a hungry bat may eat the flowers and large quantities of pollen. Some bats are reported to dine exclusively on pollen, and any plant that depends on these species for pollination is clearly willing to pay a steep price for gene dispersal. Selfishness is characteristic of other pollinators. Bees that happen across flowers whose nectaries are too deeply recessed to reach with their tongues will often crawl to the side of the blosson and chew their way to the nectar, depleting and damaging the flower without transferring any pollen. When hummingbirds set up a territory over a patch of the banana-like Heliconia plants that occupy light gaps in the rain forest, they pugnaciously evict other visitors and thereby may impede the plant's gene dispersal.

Animals are not the only selfish parties in pollination systems. The plants are equally self-serving. Some flowers attract their pollinators by deceit. Orchids are masters of this art. Some offer what appear to be nectaries but turn out to be just artful pigments. Others have hairs that resemble pollen-rich anthers but are really a ruse to lure bees where they can be dabbed with the orchid's pollen without being able to pack any away to take back to the nest. Some orchids lure bees into trap blossoms that force them against pollen-bearing structures and pollen receptors without offering any real rewards. Other orchids mimic nectar-bearing flowers, and some even play on the indiscriminate lust of male tachinid flies by mimicking females. When the male attempts to copulate with the pseudofemale, he actually pollinates the orchid. Other orchid flowers flutter in the breeze, producing a movement that male Gentris bees perceive as a territorial challenge. When they aggressively sally forth, plowing into the presumed intruder, they pick up the orchid's pollen. However, deceptive seductions like these are dependent to some extent on naive pollinators and may not work on an insect that has been duped often enough to learn to avoid the flowers. The majority of flowers, even orchids, must still offer significant rewards if they are to get dependable service.

1 comment:

You are the reason why I do not write privately. I would love to hear your thoughts, whether you agree or not.