Competitive resource sharing: An experimental test of a learning rule for ESSs

The results support the hypothesis that the fish used the relative payoff sum (RPS) learning rule (Harley 1981; Regelmann 1984) and it is compatible with the RPS learning rule that theFish reached their decision as quickly whether they were supplied with prey regularly or irregularly.

Abstract

Six sticklebacks (Gasterosteus aculeatus) distributed themselves between two simulated drift food patches in the ratio of patch profitabilities (Milinski 1979). The present study investigated the rule with which each fish decides to stay in one or the other patch, and whether the fish have more difficulties in reaching a decision when the prey is supplied irregularly as is the case under natural conditions. With frame by frame analysis of filmed experiments the hunting success and sampling effort of each individual fish could be determined continuously. The results support the hypothesis that the fish used the relative payoff sum (RPS) learning rule (Harley 1981; Regelmann 1984). There was a close correlation between all decisions of individual fish during a trial, whether to stay or leave a patch, and decisions predicted by the RPS learning rule using the actual experience of the fish. Differences in competitive ability between the fish influenced the dynamics of the distribution in the predicted way, the more successful competitors deciding earlier where to stay than the less successful ones. This had the effect that the good competitors as well as the poor ones were distributed between the patches in the ratio of patch profitabilities. It is also compatible with the RPS learning rule that the fish reached their decision as quickly whether they were supplied with prey regularly or irregularly.