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. "The game can help describe the diversity of species," explains Frey. "The background is a branch of mathematics called game theory, and in this case evolutionary game theory. It helps analyze systems that involve multiple actors whose interactions are similar to those in parlor games."
Using game theory, one can also study the collective development of populations. 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," says Frey.
This "law of the weakest" even held true when the difference between the competing species was slight. "This result was just as unexpected for us," reports Frey. "But it shows once more that chance plays a big part in the dynamics of an ecosystem. Incidentally, in experiments that were conducted a couple of years ago on bacterial colonies, in order to study cyclical competition,
|Contact: Luise Dirscherl|