A Test of Neutral Molecular Evolution Based on Nucleotide Data

TLDR

The neutral theory predicts that genomic regions with high interspecific divergence will also show high intraspecific polymorphism. The authors aim to test this prediction with a conservative statistical test based on a constant‑rate neutral model. The test requires interspecific comparisons of at least two genomic regions and intraspecific polymorphism data from the same regions in at least one species. The model is rejected for the Adh locus and its 5′ flanking sequence in *Drosophila melanogaster* and *Drosophila sechellia*, with departures consistent with balanced polymorphism in the coding region.

Abstract

ABSTRACT The neutral theory of molecular evolution predicts that regions of the genome that evolve at high rates, as revealed by interspecific DNA sequence comparisons, will also exhibit high levels of polymorphism within species. We present here a conservative statistical test of this prediction based on a constant-rate neutral model. The test requires data from an interspecific comparison of at least two regions of the genome and data on levels of intraspecific polymorphism in the same regions from at least one species. The model is rejected for data from the region encompassing the Adh locus and the 5′ flanking sequence of Drosophila melanogaster and Drosophila sechellia. The data depart from the model in a direction that is consistent with the presence of balanced polymorphism in the coding region.