. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. EVOLUTION OF SELF-ORGANIZED SYSTEMS 259. 100 200 300 Generations 400 500 40 S30 £• 20 o o o 10 100 200 300 Generations 400 500 Figure 2. The outcome of selection for various rule sets in the genetic algorithm described in the text. (A) The proportion of colonies that obey the JI = I, J2 = 1,73= 1 or 74 = 1 rule through time, starting with a colony size of three workers with all workers obeying the rule 71 = 72 = 73 = 74 = 0. 73 = 1 becomes fixed in the population first, followed rapidly by 71 = 1. Both the 72 = 1 and the 74
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. EVOLUTION OF SELF-ORGANIZED SYSTEMS 259. 100 200 300 Generations 400 500 40 S30 £• 20 o o o 10 100 200 300 Generations 400 500 Figure 2. The outcome of selection for various rule sets in the genetic algorithm described in the text. (A) The proportion of colonies that obey the JI = I, J2 = 1,73= 1 or 74 = 1 rule through time, starting with a colony size of three workers with all workers obeying the rule 71 = 72 = 73 = 74 = 0. 73 = 1 becomes fixed in the population first, followed rapidly by 71 = 1. Both the 72 = 1 and the 74 = 1 rule transiently reach high proportions before declining in frequency. The 71 = 1 and 73 = 1 rules do not remain fixed due to recurrent mutation. (B) The average colony size of the 1000 colonies composing the population. set and colony size. The mutation rate, going up or down in colony size (in one-worker increments) or changing one of the rules (from 0 to 1 or back) was The population of 1000 colonies was repopulated by random replication of colonies with probabilities based on a colony's relative fitness. The outcome of this genetic algorithm is shown in Figure 2a. Both rules J_, = 1 and 7, = 1 rapidly go to near fixation in the population. Other rules are transiently selected for because colony size is changing as well (Fig. 2b). Selection on transit time produced a rule set that generates self- organized activity cycles. These self-organized patterns are themselves not the outcome of selection; they have no effect on function or fitness, and yet they appear due to selection on transit time. They are a correlated response to selection. A second consequence of this selection is that it produces activity patterns of greater complexity. For each rule set. I measured the complexity of the activity record as the aver- age mutual information per pair of ants (Langton, 1992; Sole and Miramontes, 1995). The mutual information in a pair of activity records is the sum of
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
