A motionless green background? 2

ArgentieriNatura, PsicologiaLeave a Comment

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I’ve already quoted Michael Crichtons “Jurassic Park” three years ago, when I opened this blog. But also in another post quoting the paleobotany Ellise Sattler and her considerations on the plants used in the park. I liked the info Crichton reported which carified the idea that nature is not that motionless green background a superficial eye may see.
In the sequel to Jurassic Park, “The Lost World”, Crichton talks again about this topic, particularly important according to him and me: changing our perspective toward nature may change our attitude toward it, too. And it may help that shift of conscience necessary to help our species to survive a massive climate change that we are provoking ourselves.

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“Plants have defenses?” Kelly said.
“Of course they do. Plants evolve like every other form of life, and they’ve come up with their own forms of aggression, defense, and so on. In the nineteenth century, most theories concerned animals – nature red in tooth and claw, all that. But now scientists are thinking about nature green in root and stem.
We realize that plants, in their ceaseless struggle to survive, have evolved everything from complex symbiosis with other animals, to signaling mechanisms to warn other plants, to outright chemical warfare.”
Kelly frowned. “Signaling? Like what?”
“Oh, there are many examples,” Levine said. “In Africa acacia trees evolved very long, sharp thorns – three inches or so – but that only provoked animals like giraffes and antelope to evolve long tongues to get past the thorns. Thorns alone didn’t work. So in the evolutionary arms race, the acacia trees next evolved toxicity. They started to produce large quantities of tannin in their leaves, which sets off a lethal metabolic reaction in the animals that eat them. Literally kills them. At the same time, the acacias also evolved a kind of chemical warning system among themselves. If an antelope begins to eat one tree in a grove, that tree releases the chemical ethylene into the air, which causes other trees in the grove to step up the production of leaf tannin. Within five or ten minutes, the other trees are producing more tannin, making themselves poisonous.
“And then what happens to the antelope? It dies?”
“Well, not any more,” Levine said, “because the evolutionary arms race continued, Eventually, antelopes learned that they could only browse for a short time. Once the trees started to produce more tannin, they had to stop eating it. And the browsers developed new strategies. For example, when a giraffe eats an acacia tree, it then avoids all the trees downwind. Instead, it moves on to another tree that is some distance away. So the animals have adapted to this defense, too.”
“In evolutionary theory, this is called the Red Queen phenomenon,” Malcolm said. “Because in Alice in Wonderland the Red Queen tells Alice she has to run as fast as she can just to stay where she is. That’s the way evolutionary spirals seem. All the organisms are evolving at a furious pace just to stay in the same balance. To stay where they are.”
Arby said, “And this is common? Even with plants?”
“Oh yes,” Levine said. “In their own way, plants are extremely active. Oak trees, for example, produce tannin and phenol as a defense when caterpillars attack them. A whole grove of trees is alerted as soon as one tree is infested. It’s a way to protect the entire grove – a kind of cooperation among trees, you might say.”


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