Evidence of genotypic adaptation to the exposure to volcanic risk at the dopamine receptor DRD4 locus.

Charlotte Faurie,Evi Dwi Lestari,Danang Sri Hadmoko,Mohamed Ali Bchir,Carine Heitz,Clement Mettling,Marc Willinger,Michel Raymond

doi:10.1038/srep37745

Abstract

Humans have colonized and adapted to extremely diverse environments, and the genetic basis of some such adaptations, for example to high altitude, is understood. In some cases, local or regional variation in selection pressure could also cause behavioural adaptations. Numerous genes influence behaviour, such as alleles at the dopamine receptor locus D4 (DRD4), which are associated with attitude toward risk in experimental settings. We demonstrate genetic differentiation for this gene, but not for five unlinked microsatellite loci, between high- and low risk environments around Mount Merapi, an active volcano in Java, Indonesia. Using a behavioural experiment, we further show that people inhabiting the high risk environment are significantly more risk averse. We provide evidence of a genetic basis for this difference, showing that heterozygotes at the DRD4 locus are more risk averse than either homozygotes. In the high risk environment, allele frequencies are equilibrated, generating a high frequency of heterozygotes. Thus it appears that overdominance (i.e. selective advantage of heterozygotes) generates negative frequency dependent selection, favouring the rarer allele at this locus. Our results therefore provide evidence for adaptation to a marginal habitat through the selection of a neurocognitive trait with a genetic basis.

Highlights

The distance from birthplace to place of residence was 1.7 ± 0.1 km, which is small compared to the size of the risky area (500–800 km2), suggesting that only moderate selective effects could generate local adaptation
The effect of the 7 R allele on risk-taking behaviour previously reported by Dreber et al.[12] may be an effect of the heterozygote
7 R is a minor allele in the Western population studied, the frequency of 7 R homozygotes being less than 2%, so the effect of the 7 R allele in the studied population was mainly observed in heterozygotes and a far larger sample would have been required to detect an effect of homozygotes for this allele

Summary

Introduction

The distance from birthplace to place of residence was 1.7 ± 0.1 km (estimation based on 2,808 individuals, including participants, their parents, and grandparents), which is small compared to the size of the risky area (500–800 km2), suggesting that only moderate selective effects could generate local adaptation. People living in the risky environment chose to invest less money in the risky option (Fig. 1), indicating that they are significantly more risk averse (Wilcoxon test, W = 8838, P = 0.038).

Results

Conclusion