Genetics. Published Articles Ahead of Print: February 3, 2008, Copyright © 2008
doi:10.1534/genetics.107.085423


A more recent version of this article appeared on May 1, 2008.

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Evidence of spatially varying selection acting on four chromatin remodeling loci in Drosophila melanogaster

Mia T Levine 1* and David J Begun 1

1 University of California, Davis

* To whom correspondence should be addressed. E-mail: mialevine{at}ucdavis.edu.

Submitted on December 4, 2007
Revised on January 4, 2008
Accepted on 12 January 2008


Abstract

The packaging of DNA into proper chromatin structure contributes to transcriptional regulation. This packaging is environment-sensitive, yet its role in adaptation to novel environmental conditions is completely unknown. We set out to identify candidate chromatin remodeling loci that are differentiated between tropical and temperate populations in D. melanogaster, an ancestrally equatorial African species that has recently colonized temperate environments around the world. Here we describe sequence variation at seven such chromatin remodeling loci, four of which (chd1, ssrp, chm, and glu) exhibit strong sequence differentiation between tropical and temperate populations. An in depth analysis of chm revealed sequence differentiation restricted to a small portion of the gene, as well as evidence of clinal variation along the east coasts of both the US and Australia. The functions of chd1, chm, ssrp, and glu point to several novel hypotheses for the role of chromatin-based transcriptional regulation in adaptation to a novel environment. Specifically, both stress-induced transcription and developmental homeostasis emerge as potential functional targets of environment-dependent selection.

Key Words: chameau, chromatin remodeling, cline, developmental homeostasis, stress