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Mol. Biol. Evol. 18(3):279290. 2001 2001 by the Society for Molecular Biology and Evolution. ISSN: 0737-4038
 

Summary: 279
Mol. Biol. Evol. 18(3):279290. 2001
2001 by the Society for Molecular Biology and Evolution. ISSN: 0737-4038
Contrasting Patterns of X-Linked and Autosomal Nucleotide Variation in
Drosophila melanogaster and Drosophila simulans
Peter Andolfatto
Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh, Scotland
Surveys of molecular variation in Drosophila melanogaster and Drosophila simulans have suggested that diversity
outside of Africa is a subset of that within Africa. It has been argued that reduced levels of diversity in non-African
populations reflect a population bottleneck, adaptation to temperate climates, or both. Here, I summarize the avail-
able single-nucleotide polymorphism data for both species. A simple ``out of Africa'' bottleneck scenario is con-
sistent with geographic patterns for loci on the X chromosome but not with loci on the autosomes. Interestingly,
there is a trend toward lower nucleotide diversity on the X chromosome relative to autosomes in non-African
populations of D. melanogaster, but the opposite trend is seen in African populations. In African populations,
autosomal inversion polymorphisms in D. melanogaster may contribute to reduced autosome diversity relative to
the X chromosome. To elucidate the role that selection might play in shaping patterns of variability, I present a
summary of within- and between-species patterns of synonymous and replacement variation in both species. Overall,
D. melanogaster autosomes harbor an excess of amino acid replacement polymorphisms relative to D. simulans.
Interestingly, range expansion from Africa appears to have had little effect on synonymous-to-replacement poly-
morphism ratios.

  

Source: Andolfatto, Peter - Department of Ecology and Evolutionary Biology, Princeton University

 

Collections: Biology and Medicine