Fine-mapping and selective sweep analysis of QTL for cold tolerance in Drosophila melanogaster.

Ricardo Wilches,Pablo Duchen,Susanne Voigt,Stefan Laurent,Wolfgang Stephan

doi:10.1534/g3.114.012757

Ricardo Wilches, Pablo Duchen + Show 3 more

Open Access

https://doi.org/10.1534/g3.114.012757

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Abstract

There is a growing interest in investigating the relationship between genes with signatures of natural selection and genes identified in QTL mapping studies using combined population and quantitative genetics approaches. We dissected an X-linked interval of 6.2 Mb, which contains two QTL underlying variation in chill coma recovery time (CCRT) in Drosophila melanogaster from temperate (European) and tropical (African) regions. This resulted in two relatively small regions of 131 kb and 124 kb. The latter one co-localizes with a very strong selective sweep in the European population. We examined the genes within and near the sweep region individually using gene expression analysis and P-element insertion lines. Of the genes overlapping with the sweep, none appears to be related to CCRT. However, we have identified a new candidate gene of CCRT, brinker, which is located just outside the sweep region and is inducible by cold stress. We discuss these results in light of recent population genetics theories on quantitative traits.

Highlights

There is a growing interest in investigating the relationship between genes with signatures of natural selection and genes identified in QTL mapping studies using combined population and quantitative genetics approaches
We found that the genes within the selective sweep region are probably not related to the trait, but a gene just outside the sweep is induced by cold stress
With the set of 24 deficiencies (Figure 1), we could potentially uncover the effect of line-specific alleles at 588 (95%) of the 622 annotated and computationally predicted genes within the interval

Summary

Introduction

There is a growing interest in investigating the relationship between genes with signatures of natural selection and genes identified in QTL mapping studies using combined population and quantitative genetics approaches. We dissected an X-linked interval of 6.2 Mb, which contains two QTL underlying variation in chill coma recovery time (CCRT) in Drosophila melanogaster from temperate (European) and tropical (African) regions This resulted in two relatively small regions of 131 kb and 124 kb. We have identified a new candidate gene of CCRT, brinker, which is located just outside the sweep region and is inducible by cold stress We discuss these results in light of recent population genetics theories on quantitative traits. There is the view that the molecular population genetics scenario of selective sweeps is important in describing selection on quantitative traits These sweeps may be caused by new mutations or low-frequency alleles from the standing variation. We found that the genes within the selective sweep region are probably not related to the trait, but a gene (brinker) just outside the sweep is induced by cold stress

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Conclusion