Population transcriptomes reveal synergistic responses of DNA polymorphism and RNA expression to extreme environments on the Qinghai–Tibetan Plateau in a predatory bird

• Published in: Molecular ecology Vol. 26; no. 11; pp. 2993 - 3010
• Main Authors: Pan, Shengkai, Zhang, Tongzuo, Rong, Zhengqin, Hu, Li, Gu, Zhongru, Wu, Qi, Dong, Shanshan, Liu, Qiong, Lin, Zhenzhen, Deutschova, Lucia, Li, Xinhai, Dixon, Andrew, Bruford, Michael W., Zhan, Xiangjiang
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.06.2017
• Subjects: Adaptation; Adaptations; Altitude; Animals; Colonization; Deoxyribonucleic acid; DNA; Extreme Environments; Falconiformes - genetics; Gene expression; Genes; Genetics, Population; Genomes; Grasslands; High altitude; Hypothermia; Hypoxia; Immune response; Immune system; Modules; Molecular modelling; Oxygen; Oxygen enrichment; Polymorphism; Polymorphism, Genetic; Population studies; population transcriptome; Predators; Qinghai–Tibetan Plateau; Ribonucleic acid; RNA; RNA - genetics; RNA sequencing; saker falcon; Stresses; Temperature effects; Tibet; Transcription factors; Transcriptome; Tibetan Plateau; RNA sequencing; adaptation; population transcriptome; saker falcon; colonization; Qinghai-Tibetan Plateau
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/mec.14090

Low oxygen and temperature pose key physiological challenges for endotherms living on the Qinghai–Tibetan Plateau (QTP). Molecular adaptations to high‐altitude living have been detected in the genomes of Tibetans, their domesticated animals and a few wild species, but the contribution of transcriptional variation to altitudinal adaptation remains to be determined. Here we studied a top QTP predator, the saker falcon, and analysed how the transcriptome has become modified to cope with the stresses of hypoxia and hypothermia. Using a hierarchical design to study saker populations inhabiting grassland, steppe/desert and highland across Eurasia, we found that the QTP population is already distinct despite having colonized the Plateau <2000 years ago. Selection signals are limited at the cDNA level, but of only seventeen genes identified, three function in hypoxia and four in immune response. Our results show a significant role for RNA transcription: 50% of upregulated transcription factors were related to hypoxia responses, differentiated modules were significantly enriched for oxygen transport, and importantly, divergent EPAS1 functional variants with a refined co‐expression network were identified. Conservative gene expression and relaxed immune gene variation may further reflect adaptation to hypothermia. Our results exemplify synergistic responses between DNA polymorphism and RNA expression diversity in coping with common stresses, underpinning the successful rapid colonization of a top predator onto the QTP. Importantly, molecular mechanisms underpinning highland adaptation involve relatively few genes, but are nonetheless more complex than previously thought and involve fine‐tuned transcriptional responses and genomic adaptation.