Molecular evolution of a pervasive natural amino-acid substitution in Drosophila cryptochrome

Mirko Pegoraro, Shumaila Noreen, Supriya Bhutani, Avgi Tsolou, Ralf Schmid, Charalambos P Kyriacou, Eran Tauber

Research output: Contribution to journalArticlepeer-review

Abstract

Genetic variations in circadian clock genes may serve as molecular adaptations, allowing populations to adapt to local environments. Here, we carried out a survey of genetic variation in Drosophila cryptochrome (cry), the fly's dedicated circadian photoreceptor. An initial screen of 10 European cry alleles revealed substantial variation, including seven non-synonymous changes. The SNP frequency spectra and the excessive linkage disequilibrium in this locus suggested that this variation is maintained by natural selection. We focused on a non-conservative SNP involving a leucine-histidine replacement (L232H) and found that this polymorphism is common, with both alleles at intermediate frequencies across 27 populations surveyed in Europe, irrespective of latitude. Remarkably, we were able to reproduce this natural observation in the laboratory using replicate population cages where the minor allele frequency was initially set to 10%. Within 20 generations, the two allelic variants converged to approximately equal frequencies. Further experiments using congenic strains, showed that this SNP has a phenotypic impact, with variants showing significantly different eclosion profiles. At the long term, these phase differences in eclosion may contribute to genetic differentiation among individuals, and shape the evolution of wild populations.

Original languageEnglish
Pages (from-to)e86483
JournalPLoS ONE
Volume9
Issue number1
DOIs
Publication statusPublished - 24 Jan 2014

Keywords

  • Alleles
  • Amino Acid Substitution
  • Animals
  • Circadian Rhythm
  • Cryptochromes
  • Drosophila Proteins
  • Drosophila melanogaster
  • Europe
  • Evolution, Molecular
  • Eye Proteins
  • Female
  • Gene Frequency
  • Haplotypes
  • Linkage Disequilibrium
  • Male
  • Models, Molecular
  • Phenotype
  • Polymorphism, Single Nucleotide
  • Selection, Genetic

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