Evidence for positive selection on α and β globin genes in pikas and zokor from the Qinghai-Tibetan Plateau

Elevation as a selective force on mitochondrial respiratory chain complexes of the Phrynocephalus lizards in the Tibetan plateau

Current Zoology ◽

10.1093/cz/zoaa056 ◽

2020 ◽

Author(s):

Yuanting Jin ◽

Y C Brandt Débora ◽

Jiasheng Li ◽

Yubin Wo ◽

Haojie Tong ◽

...

Keyword(s):

Tibetan Plateau ◽

Positive Selection ◽

High Altitude ◽

Respiratory Chain ◽

Mitochondrial Respiratory Chain ◽

Oxygen Availability ◽

The Tibetan Plateau ◽

Respiratory Chain Complexes ◽

Chain Complexes ◽

Assembly Factors

Abstract Animals living in extremely high elevations have to adapt to low temperatures and low oxygen availability (hypoxia), but the underlying genetic mechanisms associated with these adaptations are still unclear. The mitochondrial respiratory chain can provide >95% of the ATP in animal cells, and its efficiency is influenced by temperature and oxygen availability. Therefore, the respiratory chain complexes (RCCs) could be important molecular targets for positive selection associated with respiratory adaptation in high-altitude environments. Here, we investigated positive selection in 5 RCCs and their assembly factors by analyzing sequences of 106 genes obtained through RNA-seq of all 15 Chinese Phrynocephalus lizard species, which are distributed from lowlands to the Tibetan plateau (average elevation >4,500 m). Our results indicate that evidence of positive selection on RCC genes is not significantly different from assembly factors, and we found no difference in selective pressures among the 5 complexes. We specifically looked for positive selection in lineages where changes in habitat elevation happened. The group of lineages evolving from low to high altitude show stronger signals of positive selection than lineages evolving from high to low elevations. Lineages evolving from low to high elevation also have more shared codons under positive selection, though the changes are not equivalent at the amino acid level. This study advances our understanding of the genetic basis of animal respiratory metabolism evolution in extreme high environments and provides candidate genes for further confirmation with functional analyses.

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Species groups distributed across elevational gradients reveal convergent and continuous genetic adaptation to high elevations

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1813593115 ◽

2018 ◽

Vol 115 (45) ◽

pp. E10634-E10641 ◽

Cited By ~ 16

Author(s):

Yan-Bo Sun ◽

Ting-Ting Fu ◽

Jie-Qiong Jin ◽

Robert W. Murphy ◽

David M. Hillis ◽

...

Keyword(s):

Tibetan Plateau ◽

Positive Selection ◽

Rapid Change ◽

Elevational Gradient ◽

High Elevation ◽

Individual Gene ◽

Evolutionary Changes ◽

Species Groups ◽

The Individual ◽

High Elevations

Although many cases of genetic adaptations to high elevations have been reported, the processes driving these modifications and the pace of their evolution remain unclear. Many high-elevation adaptations (HEAs) are thought to have arisen in situ as populations rose with growing mountains. In contrast, most high-elevation lineages of the Qinghai-Tibetan Plateau appear to have colonized from low-elevation areas. These lineages provide an opportunity for studying recent HEAs and comparing them with ancestral low-elevation alternatives. Herein, we compare four frogs (three species ofNanoranaand a close lowland relative) and four lizards (Phrynocephalus) that inhabit a range of elevations on or along the slopes of the Qinghai-Tibetan Plateau. The sequential cladogenesis of these species across an elevational gradient allows us to examine the gradual accumulation of HEA at increasing elevations. Many adaptations to high elevations appear to arise gradually and evolve continuously with increasing elevational distributions. Numerous related functions, especially DNA repair and energy metabolism pathways, exhibit rapid change and continuous positive selection with increasing elevations. Although the two studied genera are distantly related, they exhibit numerous convergent evolutionary changes, especially at the functional level. This functional convergence appears to be more extensive than convergence at the individual gene level, although we found 32 homologous genes undergoing positive selection for change in both high-elevation groups. We argue that species groups distributed along a broad elevational gradient provide a more powerful system for testing adaptations to high-elevation environments compared with studies that compare only pairs of high-elevation versus low-elevation species.

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