Genome of Laudakia sacra Provides New Insights into High-Altitude Adaptation of Ectotherms.

Anan's rock agama ( Laudakia sacra ) is a lizard species endemic to the harsh high-altitude environment of the Qinghai-Tibet Plateau, a region characterized by low oxygen tension and high ultraviolet (UV) radiation. To better understand the genetic mechanisms underlying highland adaptation of ectotherms, we assembled a 1.80-Gb L. sacra genome, which contained 284 contigs with an N50 of 20.19 Mb and a BUSCO score of 93.54%. Comparative genomic analysis indicated that mutations in certain genes, including HIF1A , TIE2 , and NFAT family members and genes in the respiratory chain, may be common adaptations to hypoxia among high-altitude animals. Compared with lowland reptiles, MLIP showed a convergent mutation in L. sacra and the Tibetan hot-spring snake ( Thermophis baileyi ), which may affect their hypoxia adaptation. In L. sacra , several genes related to cardiovascular remodeling, erythropoiesis, oxidative phosphorylation, and DNA repair may also be tailored for adaptation to UV radiation and hypoxia. Of note, ERCC6 and MSH2 , two genes associated with adaptation to UV radiation in T. baileyi , exhibited L. sacra -specific mutations that may affect peptide function. Thus, this study provides new insights into the potential mechanisms underpinning high-altitude adaptation in ectotherms and reveals certain genetic generalities for animals' survival on the plateau.