Patterns and mechanisms of high-elevation adaptation in reptiles and amphibians

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My research focuses on understanding patterns of the adaptation process and its genetic basis. High-elevation adaptation provides an excellent study system, because it involves multiple stressors (e,g, low oxygen, low temperature, and high UV) and a intertwined genetic basis. We will study high-elevation adaptation of Tibetan reptiles and amphibians using genomic data. 1) Lizards of Phrynocephalus vlangalii live at Tibetan region across a large elevational gradient (2000-4600m). We will sequence its genome and re-sequence 30 individuals from various elevations. Using population genetic analyses (e.g. Fst outlier analysis), we will identify genes and chromosome regions that have experienced positive selection. The functions of these genes and their potential interactions within the genetic network will be analysed. Furthermore, a reciprocal transplant experiment will be conducted. Lizards from a low and a high elevation site will be captured and transplanted. After one month of acclimation, total mRNA will be collected and digital gene expression profiles will be examined. Genes with different expression profiles will be identified. Similarly, their functions and potential interactions will be analysed. 2) Our previous genomic works on a common toad, Bufo gargarizans, have revealed several important patterns, and one of them is a strong convergent evolution of the MYBPC2 gene, which involves heart muscle contractility. We hypothesized that modifications of cardiac function play a key role in high-elevation adaptation of amphibians and predict that MYBPC2 genes of other high-elevation amphibian species share a similar convergent pattern. We will sequence this gene from at least ten other high-elevation amphibians and test our hypothesis. We will also identify key mutations within this gene along high-elevation lineages. 3) Mitochondrial genome and its co-adaptive evolution with the nuclear genome likely play a key role in thermal adaptation. Two brown frogs, Rana chensiensis (low elevations) and R. kukunoris (high elevations), hybridize across a wide range of elevations and exhibit elevation-specific dynamics. Different combinations of mitochondrial and nuclear genomes between the two species exist in natural populations. We will sequence genes from both genomes that code for the electron transport chain. We will also measure the metabolic rates of hybrid individuals with various genome combinations, as well as rates of mitochondria themselves. Reptiles and amphibians are probably better model systems for studying high-elevation adaptation and early works have revealed a more complex genetic basis, compared to mammals and birds. Poikilotherms represent the majority of animal diversity, and our work will generate widely applicable hypotheses and provide insights into the adaptation process and its genetic basis.