mind over the body. The Ophiocordyceps fungus turns the ants into zombies.
David Hughes / University of Pennsylvania
The parasites not only cause unpleasant infections; they can also take over the minds of their hosts. The fungus Ophiocordyceps , for example, require the ants to mount stems of plants, where they die and release of fungal spores in the air to infect other ants. Similarly, it would be logical for sexually transmitted parasites to force their guests to have more sex. But biologists have found very few examples of this kind. A new study may explain why.
To understand why there is not more "mind control sexual" in nature, theoretical ecologist Ludek Berec of the Biology Centre of the Academy of Sciences of the Czech Republic, and biological mathematician Daniel Maxin from Valparaiso University in Indiana, turned to mathematical modeling They created two strains of a species of parasitic hypothetical. an "ancestor" who has not made his guests have more sex, and a mutant who did. Then they both turned loose stem in a hypothetical host population and watched the parasites compete until the mutant strain died on or replaced their ancestor.
If the mutant strain has replaced its ancestor, the researchers introduced a new mutant had even more power over the sex of its host life. They then watched the two strains compete again, yet another introduced strongest mutant when former surpassed its predecessor, and so on. In this way, the species as a whole could "evolve" to exert more or less control of sexual spirit of its host.
In most simulations, the mutants did not evolve toward making their guests have more sex, the team reports in the February 7 issue of Journal of Theoretical Biology . Instead, they have either lost the ability to influence mating behavior of their host or are dead on. Researchers believe that control of the mind is too sexual energy to the parasite, causes too much harm to the host, or both. For example, the host might become so focused on sex it does not spend enough time searching for food and water. In addition, for a parasite to change the libido of its host, it might have to pay a large portion of its energy in pumping powerful hormones, which could weaken in the long term.
The results will help epidemiologists understand how sexually transmitted diseases are spread not only parasites visible to the naked eye, but also bacteria, viruses and other microscopic invaders, says evolutionary biologist Patrick Abbot, from Vanderbilt University in Nashville, which has not participated. Describe the characteristics of coupling noise and improving their host populations can also help field biologists find more of these parasites in the real world, he noted.
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