Recombination and the evolution of satellite DNA

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Abstract
Summary: In eukaryotic chromosomes, large blocks of satellite DNA are associated with regions of reduced meiotic recombination. No function of highly repeated, tandemly arranged DNA sequences has been identified so far at the cellular level, though the structural properties of satellite DNA are relatively well known. In studying the joint action of meiotic recombination, genetic drift and natural selection on the copy number of a family of highly repeated DNA (HRDNA), this paper looks at the structure–function debate for satellite DNA from the standpoint of molecular population genetics. It is shown that (i) HRDNA accumulates most probably in regions of near zero crossing over (heterochromatin), and that (ii), due to random genetic drift the effect of unequal crossover on copy numbers is stronger, the smaller the population size. As a consequence, highly repeated sequences are likely to persist longest (over evolutionary times) in small populations. The results are based on a fairly general class of models of unequal crossing over and natural selection which have been treated both analytically and by computer simulation.