Hu Xiao, Xiao Guohua, Zheng Peng, Shang Yanfang, Su Yao, Zhang Xinyu, Liu Xingzhong, Zhan Shuai, St Leger Raymond J, Wang Chengshu
Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; and.
Proc Natl Acad Sci U S A. 2014 Nov 25;111(47):16796-801. doi: 10.1073/pnas.1412662111. Epub 2014 Nov 3.
Much remains unknown regarding speciation. Host-pathogen interactions are a major driving force for diversification, but the genomic basis for speciation and host shifting remains unclear. The fungal genus Metarhizium contains species ranging from specialists with very narrow host ranges to generalists that attack a wide range of insects. By genomic analyses of seven species, we demonstrated that generalists evolved from specialists via transitional species with intermediate host ranges and that this shift paralleled insect evolution. We found that specialization was associated with retention of sexuality and rapid evolution of existing protein sequences whereas generalization was associated with protein-family expansion, loss of genome-defense mechanisms, genome restructuring, horizontal gene transfer, and positive selection that accelerated after reinforcement of reproductive isolation. These results advance understanding of speciation and genomic signatures that underlie pathogen adaptation to hosts.
关于物种形成，仍有许多未知之处。宿主与病原体的相互作用是物种多样化的主要驱动力，但物种形成和宿主转移的基因组基础仍不清楚。绿僵菌属真菌包含从宿主范围非常狭窄的专性物种到攻击多种昆虫的广性物种。通过对七个物种的基因组分析，我们证明广性物种是通过具有中间宿主范围的过渡物种从专性物种进化而来的，并且这种转变与昆虫进化并行。我们发现，特化与有性生殖的保留和现有蛋白质序列的快速进化有关，而泛化与蛋白质家族扩张、基因组防御机制丧失、基因组重组、水平基因转移以及生殖隔离加强后加速的正选择有关。这些结果推进了我们对物种形成以及病原体适应宿主背后的基因组特征的理解。
