100 million years of multigene family evolution: origin and evolution of the avian MHC class IIB

Julien Goebel,Glenn Yannic,Maria Strandh,Luca Fumagalli,Karen D Mccoy,Francesco Bonadonna,Reto Burri,Céline Serbielle,Marta Promerová

doi:10.1186/s12864-017-3839-7

Abstract

BackgroundGene duplication has led to a most remarkable adaptation involved in vertebrates’ host-pathogen arms-race, the major histocompatibility complex (MHC). However, MHC duplication history is as yet poorly understood in non-mammalian vertebrates, including birds.ResultsHere, we provide evidence for the evolution of two ancient avian MHC class IIB (MHCIIB) lineages by a duplication event prior to the radiation of all extant birds >100 million years ago, and document the role of concerted evolution in eroding the footprints of the avian MHCIIB duplication history.ConclusionsOur results suggest that eroded footprints of gene duplication histories may mimic birth-death evolution and that in the avian MHC the presence of the two lineages may have been masked by elevated rates of concerted evolution in several taxa. Through the presence of a range of intermediate evolutionary stages along the homogenizing process of concerted evolution, the avian MHCIIB provides a remarkable illustration of the erosion of multigene family duplication history.

Highlights

Gene duplication has led to a most remarkable adaptation involved in vertebrates’ host-pathogen arms-race, the major histocompatibility complex (MHC)
The origin of avian MHC class IIB (MHCIIB) lineages predates the radiation of extant birds We found that the two avian MHCIIB lineages evolved prior to the radiation of all extant birds
All analyses confirmed the presence of both MHCIIB lineages for both neognaths and palaeognaths. (Figs. 1 and 2, Additional files 2, 3, 4 and 5), unambiguously dating the duplication event leading to the evolution of the two avian MHCIIB lineages prior to the radiation of extant birds >100 mya [23]

Summary

Introduction

Gene duplication has led to a most remarkable adaptation involved in vertebrates’ host-pathogen arms-race, the major histocompatibility complex (MHC). MHC duplication history is as yet poorly understood in non-mammalian vertebrates, including birds. The duplication history and mode of evolution of the MHC have been debated over decades [2, 4,5,6,7,8], and remain obscure for major vertebrate classes, such as birds. [11, 12]) this observation suggested that the mammalian MHC rather follows a birth-death process, in which the dynamics of gene duplication (birth) and gene loss (death) are important determinants of the multigene family’s long-term evolution [10] Together with the phylogenetically scattered loss of MHC lineages (e.g. [11, 12]) this observation suggested that the mammalian MHC rather follows a birth-death process, in which the dynamics of gene duplication (birth) and gene loss (death) are important determinants of the multigene family’s long-term evolution [10]

Methods

Results

Conclusion