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Evolution and Entropy

Does evolution lead to a decrease in entropy? In the context of the current study, entropy was measured as genetic diversity in an ecological community. This measure showed occasional sharp but transient drops in entropy. These drops in entropy appear to correspond to the appearance of highly successful new genotypes whose populations come to dominate large portions of the memory, pushing other genotypes out, and generating major extinction events.

It is interesting also, that nine of the ten genotypes listed in Table 3 are parasites (all except for `c', 0070aac). The peaks of diversity loss are greatest on the occasions that parasites reappear in the community after a period of absence.

It appears likely from these observations, that these extinction episodes correspond to the emergence of novel adaptations among the evolving organisms (particularly a breaching of the hosts defense mechanisms by parasites). These adaptations bestow the bearers with the ability to dominate the memory, excluding other organisms.

This suggests a process in which random genetic changes generated by mutation and recombination explores the genotype space. Occasionally, these explorations stumble onto a significant innovation. These innovations can bestow such an advantage that the population of the new genotype explodes, generating an episode of mass extinction as it drives other genotypes out of memory. The extinction episode is noted as a sharp drop in the entropy/diversity measure. Thus, ecological entropy drops appear to correspond to the chance discovery of significant innovations.

However, continued mutation and recombination generates new variants of the successful new form. This process generally restores the community to the equilibrium entropy about as rapidly as the entropy was lost in the extinction episode.

Thomas S.Ray
Thu Aug 3 13:06:00 JST 1995