NEWS AND VIEWS†
Genomic islands of speciation or genomic islands and speciation?
Article first published online: 15 FEB 2010
© 2010 Blackwell Publishing Ltd
Volume 19, Issue 5, pages 848–850, March 2010
How to Cite
TURNER, T. L. and HAHN, M. W. (2010), Genomic islands of speciation or genomic islands and speciation?. Molecular Ecology, 19: 848–850. doi: 10.1111/j.1365-294X.2010.04532.x
- Issue published online: 15 FEB 2010
- Article first published online: 15 FEB 2010
- Received 7 December 2009; revision accepted 20 December 2009
Populations of the malaria mosquito, Anopheles gambiae, are comprised of at least two reproductively isolated, sympatric populations. In this issue, White et al. (2010) use extensive sampling, high-density tiling microarrays, and an updated reference genome to clarify and expand our knowledge of genomic differentiation between these populations. It is now clear that DNA near the centromeres of all three chromosomes are in near-perfect disequilibrium with each other. This is in stark contrast to the remaining 97% of the assembled genome, where fixed differences between populations have not been found, and many polymorphisms are shared. This pattern, coupled with direct evidence of hybridization in nature, supports models of “mosaic” speciation, where ongoing hybridization homogenizes variation in most of the genome while loci under strong selection remain in disequilibrium with each other. However, unambiguously demonstrating that selection maintains the association of these pericentric “speciation islands” in the face of gene flow is difficult. Low recombination at all three loci complicates the issue, and increases the probability that selection unrelated to the speciation process alters patterns of variation in these loci. Here, we discuss these different scenarios in light of this new data.