Selection and Distribution in Evolution

The Papuans and Iberian Roma are nearly identical on the maternal line, as measured by mtDNA. See, A New Model of Computational Genomics [1], generally. However, they have different distributions, in that if you plot the entropy of the distribution of bases at a given index in the mtDNA genome, you’ll see they produce very different graphs, with different measurable characteristics. See the charts below, with the Papuans on the left, and the Roma on the right. As a consequence, despite the fact they are plainly very closely related people on the maternal line, they must have different distributions of those same genomes. For example, posit two populations A and B. Both populations have genome X, however in population A, genome X appears 10 times, and in population B, genome X appears 4 times. As a consequence, despite the fact that both populations intersect, in that they both have at least some instances genome X, they nonetheless have different distributions of that genome, since X appears more in A than in B.


If selection is functioning well in a given population, then the distribution of genomes should eventually converge to whatever the ideal distribution is, for the environment, within the powers and perceptions of the individuals in the population (e.g., not all species will be able to identify ideal mates). As a consequence, you should be able to start out with any number of each possible genome type, and nonetheless converge to the ideal distribution of genomes, simply through selection over time. Specifically, posit a set of genomes G(t) = \{g_1, \ldots, g_k\}, where G obviously changes as a function of time t, and each g_i gives the integer count of the number of genomes of type i, at time t. This would imply that as t increases, selection will cause G(t) to converge to the ideal distribution of genomes, since the undesirable genomes will either be reduced in count over time, or die off completely. In contrast, the desirable genomes will of course flourish.

Returning to the Papuans, how is it that they have a different distribution of maternal lines, if those individual maternal lines are in fact so similar? One sensible answer is exactly this mechanic, which causes the distribution of maternal lines to reflect environmental factors, in particular paternal selection. Since the Iberian Roma live in Spain, and the Papuans live in Papua, they of course could have differing ideal distributions of mtDNA genomes. Ultimately, left to itself, a population of women will be selected by men for reproduction, and vice versa, suggesting that there’s a difference in preferences between the Iberian Roma men and the Papuan men, since the women are nearly genetically identical, as measured by mtDNA. This is obviously plausible, given that they’re very different people, at least superficially and geographically. The astonishing fact is that they are so genetically similar, despite this, leading to many of my ideas in genetics generally, in particular, the disconnect between genetics and appearance, when compared to genetics and brain power. Selection is therefore yet another explanation for how it is that mtDNA carries information about the paternal line, despite being inherited directly from the mother with little to no mutation.


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