Molecular convergent and parallel evolution among four high-elevation anuran species from the Tibetan region
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RESEARCH ARTICLE
Open Access
Molecular convergent and parallel evolution among four high-elevation anuran species from the Tibetan region Bin Lu1, Hong Jin1,2 and Jinzhong Fu1,3*
Abstract Background: To date, evidence for the relative prevalence or rarity of molecular convergent and parallel evolution is conflicting, and understanding of how these processes contribute to adaptation is limited. We compared four high-elevation anuran species (Bufo tibetanus, Nanorana parkeri, Rana kukunoris and Scutiger boulengeri) from the Tibetan region, and examined convergent and parallel amino acid substitutions between them and how they may have contributed to high-elevation adaptation. Results: Genomic data of the four high-elevation species and eight of their low-elevation close relatives were gathered. A total of 1098 orthologs shared by all species were identified. We first conducted pairwise comparisons using Zhang and Kumar’s test. Then, the Rconv index was calculated and convergence/divergence correlation plotting was conducted. Furthermore, genes under positive selection and with elevated evolutionary rate were examined. We detected a large number of amino acid sites with convergent or parallel substitutions. Several pairs of high-elevation species, in particular, R. kukunoris vs N. parkeri and B. tibetanus vs S. boulengeri, had excessive amounts of convergent substitutions compared to neutral expectation. Nevertheless, these sites were mostly concentrated in a small number of genes (3–32), and no genome-wide convergence was detected. Furthermore, the majority of these convergent genes were neither under detectable positive selection nor had elevated evolutionary rates, although functional prediction analysis suggested some of the convergent genes could potentially contribute to high-elevation adaptation. Conclusions: There is a substantial amount of convergent evolution at the amino-acid level among high-elevation amphibians, although these sites are concentrated in a few genes, not widespread across the genomes. This may attribute to the fact that all the target species are from the same environment. The relative prevalence of convergent substitutions among high-elevation amphibians provides an excellent opportunity for further study of molecular convergent evolution. Keywords: Molecular convergent evolution, High-elevation adaptation, Amphibian, Tibet, Positive selection, HSP90AA1
* Correspondence: [email protected] 1 Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China 3 Department of Integrative Biology, University of Guelph, Guelph, Canada Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The ima
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