If one further assumes that microsatellite variation is selectively neutral, they can be used to estimate the effective population size (e.g. Schug et al., 1998).
Obvious alternative hypotheses are that some form of balancing selection maintains these polymorphisms in the two species, or instead that the variation is selectively neutral and subject to genetic drift.
Specifically, for a genetic locus at which all variation is selectively neutral and there is no intralocus recombination, the genetic ancestry of a sample of size n may be modeled as a process in which each pair of lineages ancestral to the sample "coalesces" with rate equal to one.
To explain the apparent conservation of core genome regions, and reconcile it with the apparent variability of SAR11 genomes in nature, we hypothesize that the large population sizes of SAR11, and the age of these clades that is inferred from phylogenies, have allowed them to accumulate very extensive variation in genome properties that are selectively neutral [ 2].
Naturally these cases are selectively prosecuted.
It helps if adults are selectively oblivious and tolerant.
mSOD1 immediate firing motoneurons are selectively hyperexcitable.
miRNA are selectively presented in the exosomes.
Collectively, this empirical body of research suggests that the long-standing view of segregating mtDNA variation as being selectively neutral may often be misplaced.
It has been shown in several cases that adaptive genetic variation may be selectively maintained, despite homogenizing effects of gene flow (see, e.g., Cano et al. 2008; Hauser and Carvalho 2008; Nielsen, Hemmer-Hansen, Larsen, et al. 2009; Bradbury et al. 2013; Defaveri, Jonsson, et al. 2013; Teacher et al. 2013; reviewed in Orsini et al. 2013).
