The evolution of highly variable immunity genes across a passerine bird radiation.

To survive, individuals must be able to recognize and eliminate pathogens. The genes of the major histocompatibility complex (MHC) play an essential role in this process in vertebrates as their diversity affects the repertoire of pathogens that can be recognized by the immune system. Emerging evidence suggests that birds within the parvorder Passerida possess an exceptionally high number of MHC genes. However, this has yet to be directly investigated using a consistent framework, and the question of how this MHC diversity has evolved has not been addressed. We used next-generation sequencing to investigate how MHC class I gene copy number and sequence diversity varies across the Passerida radiation using twelve species chosen to represent the phylogenetic range of this group. Additionally, we performed phylogenetic analyses on this data to identify, for the first time, the evolutionary model that best describes how MHC class I gene diversity has evolved within Passerida. We found eviden...

个体为维持生存，必须能够识别并清除病原体。主要组织相容性复合体（major histocompatibility complex, MHC）基因在脊椎动物的免疫防御过程中发挥着核心作用，其多样性直接影响免疫系统可识别的病原体谱。越来越多的研究证据表明，雀小下目（parvorder Passerida）鸟类拥有数量异常繁多的MHC基因。然而，此前尚未有研究采用统一的分析框架对该现象展开直接探究，且这类MHC多样性的演化机制这一科学问题也尚未得到解答。本研究采用下一代测序（next-generation sequencing）技术，选取能够代表雀小下目系统发育范围的12个物种作为研究对象，探究该类群内MHC I类基因的拷贝数与序列多样性差异。此外，我们还针对该数据开展系统发育分析，首次明确了最能描述雀小下目内MHC I类基因多样性演化模式的进化模型。本研究发现了……