Patterns of nucleotide diversity at the regions encompassing the Drosophila insulin-like peptide (dilp) genes: demography vs. positive selection in Drosophila melanogaster

PLoS One. 2013;8(1):e53593. doi: 10.1371/journal.pone.0053593. Epub 2013 Jan 7.

Abstract

In Drosophila, the insulin-signaling pathway controls some life history traits, such as fertility and lifespan, and it is considered to be the main metabolic pathway involved in establishing adult body size. Several observations concerning variation in body size in the Drosophila genus are suggestive of its adaptive character. Genes encoding proteins in this pathway are, therefore, good candidates to have experienced adaptive changes and to reveal the footprint of positive selection. The Drosophila insulin-like peptides (DILPs) are the ligands that trigger the insulin-signaling cascade. In Drosophila melanogaster, there are several peptides that are structurally similar to the single mammalian insulin peptide. The footprint of recent adaptive changes on nucleotide variation can be unveiled through the analysis of polymorphism and divergence. With this aim, we have surveyed nucleotide sequence variation at the dilp1-7 genes in a natural population of D. melanogaster. The comparison of polymorphism in D. melanogaster and divergence from D. simulans at different functional classes of the dilp genes provided no evidence of adaptive protein evolution after the split of the D. melanogaster and D. simulans lineages. However, our survey of polymorphism at the dilp gene regions of D. melanogaster has provided some evidence for the action of positive selection at or near these genes. The regions encompassing the dilp1-4 genes and the dilp6 gene stand out as likely affected by recent adaptive events.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / genetics*
  • Animals
  • Base Sequence
  • Body Size
  • Drosophila Proteins / classification
  • Drosophila Proteins / genetics*
  • Drosophila melanogaster / genetics*
  • Evolution, Molecular
  • Gene Expression Regulation
  • Genetic Speciation
  • Insulin / genetics
  • Insulin / metabolism
  • Molecular Sequence Data
  • Nucleotides / genetics*
  • Phenotype
  • Phylogeny
  • Polymorphism, Genetic*
  • Protein Isoforms / classification
  • Protein Isoforms / genetics
  • Selection, Genetic
  • Signal Transduction
  • Somatomedins / classification
  • Somatomedins / genetics*

Substances

  • Drosophila Proteins
  • Insulin
  • Nucleotides
  • Protein Isoforms
  • Somatomedins

Grants and funding

SG-R was supported by a predoctoral fellowship from Ministerio de Educación y Ciencia (Spain). This work was supported by grants BFU 2004-02253 and BFU 2007-63229 from Comissió Interdepartamental de Ciencia i Tecnologia, Spain, and grants 2005 SGR/00166 and 2009 SGR/1287 from Comissió Interdepartamental de Recerca i Innovació Tecnològica, Generalitat de Catalunya, Spain, to MA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.