Population genetic structure underlying the geographic variation in beetle structural colour with multiple transition...

Area of Science:

• Evolutionary biology
• Population genetics
• Animal coloration

Background:

• The geotrupid dung beetle, Phelotrupes auratus, displays striking geographic variation in structural color, appearing as red, green, and indigo forms.
• These color forms exhibit parapatric distribution within Japan, raising questions about the genetic mechanisms maintaining this variation.

Purpose of the Study:

• To investigate the population genetic structure associated with the geographic color variation in Phelotrupes auratus.
• To determine the role of gene flow, selection, and genetic loci in maintaining distinct color forms within the species.

Main Methods:

• Analysis of population genetic structure using single nucleotide polymorphisms (SNPs) from restriction-site-associated DNA sequencing.
• Identification of genetic clusters and hybrid zones between color forms.
• Genome-wide association study to pinpoint SNPs linked to specific color variations.

Main Results:

• Five distinct population groups were identified based on genetic clusters (west, south, east) and color forms (red, green, indigo).
• Two hybrid zones between red and green forms showed steep genetic clines, indicating barriers to gene flow.
• A transition zone between green and indigo forms lacked genetic differentiation, suggesting regionally specific selection.
• Four unlinked SNPs were associated with color variation, implying polygenic control of coloration.

Conclusions:

• Geographic color variation in Phelotrupes auratus is maintained by a combination of factors, including barriers to gene flow and locally specific selection.
• Multiple genetic loci, each influencing different color ranges, contribute to the observed color diversity and transitions.
• The interplay between genetic structure, selection pressures, and multiple color loci drives the evolution of distinct phenotypes within this species.