International Conference on Evolution in Singapore

List of Accepted Abstracts

HomeList of Accepted Abstracts
Adaptive expansion of ERVK solo-LTRs in accompanying with Passeriformes speciation
by Guangji Chen | Dan Yu | Yu Yang | Xiang Li | Xiaojing Wang | Danyang Sun | Yanlin Lu | Rongqin Ke | Jie Cui | Guojie Zhang | Shaohong Feng | College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China | Center for Evolutionary & Organismal Biology, Zhejiang University, Hangzhou 310058, China | School of Medicine, Huaqiao University, Xiamen, Fujian 361021, China | CAS Key Laboratory of Molecular Virology & Immunology, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai 210031, China | CAS Key Laboratory of Molecular Virology & Immunology, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai 210031, China | Center for Evolutionary & Organismal Biology, Zhejiang University, Hangzhou 310058, China | Center for Evolutionary & Organismal Biology, Zhejiang University, Hangzhou 310058, China | School of Medicine, Huaqiao University, Xiamen, Fujian 361021, China | CAS Key Laboratory of Molecular Virology & Immunology, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai 210031, China | Center for Evolutionary & Organismal Biology, Zhejiang University, Hangzhou 310058, China | Center for Evolutionary & Organismal Biology, Zhejiang University, Hangzhou 310058, China
Abstract ID: 155
Event: The 3rd AsiaEvo Conference
Topic: The genomics of adaptation and speciation
Presenter Name: Guangji Chen

Endogenous retroviruses (ERVs) are residues of ancient viral infections in host genomes. In the absence of selection pressures to maintain their components intact, ERVs are commonly deleted through unequal homologous recombination between two flanking long terminal repeats (LTRs). This process leaves residues of solitary LTRs (solo-LTRs) in a host’s genome. We detected and compared the composition of solo-LTRs in 362 bird species and their outgroups in reptiles and mammals. We discovered a substantially higher frequency of solo-LTRs in bird genomes than in mammals and reptiles, indicating strong selective pressures to purge ERVs from bird genomes. Most strikingly, in the diverse bird order Passeriformes, and especially in the parvorder Passerida, endogenous retrovirus-K (ERVK) family solo-LTRs showed bursts of formation and recurrent accumulation that corresponded to speciation events during the past 22 million years. Moreover, our results indicate that the continuous expansion of ERVK solo-LTRs is still an ongoing process in these bird species in confronting the high transcriptional activity of ERVK retroviral genes in their reproductive organs, resulting in high variation of solo-LTRs between individuals of zebra finches, a representative species under Passerida. Interestingly, we found that specific ERVK solo-LTRs contain cis-elements with potential regulatory functions. We experimentally demonstrated that the promoter activity of recently evolved ERVK solo-LTRs in the zebra finch leads to significantly higher expression of the ITGA2 gene in the high vocal center (HVC) and robust nucleus of the arcopallium (RA) regions of this species compared to an ortholog in chicken. These findings suggest that the expansion of solo-LTRs may introduce novel genomic sequences that serve as cis-regulatory elements to host genomes and enhance regulatory networks, contributing to adaptive evolution. These findings underscore that the residual sequences of ancient viruses can influence the adaptive diversification of species by regulating gene expression.