Antimicrobial peptide and sequence variation along a latitudinal gradient in two anurans

Area of Science:

• Evolutionary genetics
• Immunology
• Zoology

Background:

• Antimicrobial peptides (AMPs) are crucial for innate immunity.
• Genetic diversity of AMPs in ranid frogs (Rana arvalis and R. temporaria) was previously uninvestigated.
• This study examined AMP genetic diversity along a 2000 km latitudinal gradient.

Purpose of the Study:

• To investigate the genetic diversity of three AMP loci (Temporin, Brevinin, Palustrin) in two frog species.
• To determine if AMP genetic variation follows a latitudinal pattern, similar to MHC genes.
• To explore the evolutionary pressures acting on AMP genes.

Main Methods:

• Amplification and sequencing of AMP gene domains (Acidic Propiece and Mature Peptide).
• Utilized Illumina Miseq for sequencing.
• Applied codon evolution models to analyze selection pressures.

Main Results:

• High gene diversity was found across multiple AMP loci.
• No clear geographic genetic structure was observed along the latitudinal gradient.
• Evidence of trans-specific polymorphism, positive selection, and diversifying selection on the Mature Peptide domain was detected.

Conclusions:

• Antimicrobial peptides (AMPs) represent a significant source of adaptive genetic diversity.
• This diversity helps mitigate the risk of microorganisms developing resistance to specific peptides.
• The findings highlight the role of AMPs in host-pathogen co-evolution.