martedì 12 novembre 2013

“Amici falsi”

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by Siziliano

Dear all, besides fascinating excavations, fights against the “golfo dei Fenici” and fights for scripture to which many of you are dedicated, allow me sending information on a stupendous observation that I read in the literature.

An article from Martin Heil, Centro de Investiation y de Estudios Avancados del Instituto Politecnico National (Mexico) in Ecology Letters describes a special aspect of “Symbiosis” or “Mutualism”. Best example for such phenomenon is the coevolution of honey bee and flower, but there are many more examples in nature, as, e.g., the cleaning of crocodile teeth or of rhinoceros skin by birds. This is often, but not always, with a mutual benefit for both involved partners.

Here comes the observation from Martin Heil and his colleagues that studied a particularly perfidious relation between a special ant species and Acacia-trees in Mexico. These ants live in enormous, huge colonies on these trees and act as a guard, such that they protect the trees against other insect enemies that would damage or even kill the trees by feeding exhaustively on the leaves and the bark. The ants even remove climbing plants that would grow on the Acacia trees. The beneficial activity of the ants is readily documented from trees that have been left from their guard and are heavily suffering, even dying.

The ants benefit, as the tree “offers” home and nutrition, as the ants exclusively live on the sweet sirup (nectar) that the tree offers. So, good for both sides? In particular as science said that the ants suffer from a particular nutritional intolerance, as these insects are not able to metabolize normal sugar (saccharose) due to a defect in one of the required enzymes. In fact the juice of the Acacia trees does not contain the normal sugar.

Now, scientists followed this special care-taking, asking themselves “well, why not simply help myself” and eat the nectar from the tree without further defense activities? They took larvae of the ants and let them hatch in the laboratory. Some larvae were grown on regular nutrition sources (e.g., normal sugar), others on the Acacia nectar. SURPRISE!!! The larvae that hatched in the lab – were truly able to metabolize saccharose, the normal sugar! SO?? No genetic defect.
… but: the Acacia nectar contains another enzyme that BLOCKS the metabolism of the ants required to digest normal sugar”. So, a freshly hatched worker ant that feeds the first time the Acacia nectar, loses the capacity to metabolise sugar, and thus has no other chance than to live on Acacia nectar, accordingly, the ant protects her nutritional source.

Comment by the authors: “this is something from a science fiction film – soldiers driven into dependence and urged to follow the defense duty just not to die from starving. This is really perfidious

So, comment from me: have a look at your real best friends.

Siziliano

This came from an article in Spiegel online (Spiegel.de), the original article is in “Ecology Letters”.

Martin Heil, Alejandro Barajas-Barron, Domancar Orona-Tamayo, Natalie Wielsch, Ales Svatos, Partner manipulation stabilises a horizontally transmitted mutualism, 2013, Ecology Letters, DOI: 10.1111/ele.12215