Poster Presentation Society for Molecular Biology and Evolution Conference 2016

Selection acting on major histocompatibility complex class I genes in Japanese Ranidae frogs (#354)

Quintin Lau 1 , Takeshi Igawa 2 , Shohei Komaki 3 , Yoko Satta 1
  1. Department of Evolutionary Studies of Biosystems, Sokendai (The Graduate University for Advanced Studies), Hayama, Kanagawa, Japan
  2. Global Career Design Center, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
  3. Graduate School of International Development and Cooperation, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan

The major histocompatibility complex (MHC) is an important component of adaptive immunity in all jawed vertebrates, and understanding the evolutionary mechanisms that have shaped these genes in amphibians, one of the earliest terrestrial tetrapods, is important. We characterised MHC class I variation in three common Japanese Rana species (Rana japonica, Rana ornativentris, and Rana tagoi tagoi) and identified a total of 60 variants from 21 individuals. We also found evolutionary signatures of gene duplication, recombination and balancing selection (including trans-species polymorphism), all of which drive increased MHC diversity. A unique feature of MHC class I from these three Ranidae species includes low synonymous differences per site (dS) within species, attributed to a more recent diversification of these sequences or recent gene duplication. The resulting higher dN /dS ratio relative to other anurans studied could be related to stronger selection pressure at peptide binding sites. This is one of the first studies to investigate MHC in Japanese amphibians, and permits further exploration of the polygenetic factors associated with resistance to infectious diseases.