Sometimes, it’’s the survival of the weakest!

February 15th, 2009 - 1:04 pm ICT by ANI  

Munich, Feb 15 (ANI): A simulation developed by researchers has surprisingly suggested that it’’s not always the fittest of the species that prevails; sometimes, the weakest can also become a winner. The extinction of species is a consequence of their inability to adapt to new environmental conditions, and also of their competition with other species. Besides selection and the appearance of new species, the possibility of adaptation is also one of the driving forces behind evolution. According to the interpretation that has been familiar since Darwin, these processes increase the “fitness” of the species overall, since, of two competing species, only the fittest would survive. Now, Ludwig-Maximilians-Universitat (LMU) Munich researchers have simulated the progression of a cyclic competition of three species. It means that each participant is superior to one other species, but will be beaten by a third interaction partner. “In this kind of cyclical concurrence, the weakest species proves the winner almost without exception,” said Professor Erwin Frey, who headed the study. “The two stronger species, on the other hand, die out, as experiments with bacteria have already shown. Our results are not only a big surprise, they are important to our understanding of evolution of ecosystems and the development of new strategies for the protection of species,” he added. Theoretical ecologists and biophysicists are intensively researching conditions and mechanisms that affect the biodiversity of Earth. Cyclic dominance is a particularly interesting constellation of species competing with each other. It means that each participant is superior to one other interaction partner, but will be beaten by a third. In ecosystems, this would be three subpopulations, in the simplified model, which dominate in turn. In fact, communities of subpopulations following such rules have been identi?ed in numerous ecosystems, ranging from coral reef invertebrates to lizards in the inner Coast Range of California. Such cyclical interaction is also familiarly termed “rock-paper-scissors” interaction. This is where the rock blunts the scissors, which cut the paper, which in turn wraps around the rock. Together, these non-hierarchical relationships form a cyclical motion. In their study, the scientists working with Frey developed elaborate computer simulations in order to calculate the probabilities with which species in cyclical competition will survive. The games started off with three species coexisting in the systems, and ran until two species became extinct, with the third being the only remaining survivors. “What we saw was that in large populations, the weakest species would - with very high probability - come out as the victor,” said Frey. (ANI)

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