Data from: Elucidating the functional evolution of heat sensors among Xenopus species adapted to different thermal niches by ancestral sequence reconstruction

Ambient temperature fluctuations are detected via the thermosensory system which allows animals to seek preferable thermal conditions or escape from harmful temperatures. Evolutionary changes in thermal perception have thus potentially played crucial roles in niche selection. The genus Xenopus (clawed frog) is suitable for investigating the relationship between thermal perception and niche selection due to their diverse latitudinal and altitudinal distributions. Here we performed comparative analyses of the neuronal heat sensors TRPV1 and TRPA1 among closely related Xenopus species (X. borealis, X. muelleri, X. laevis, and X. tropicalis) to elucidate their functional evolution and to assess whether their functional differences correlate with thermal niche selection among the species. Comparison of TRPV1 among four extant Xenopus species and reconstruction of the ancestral TRPV1 revealed that TRPV1 responses to repeated heat stimulation were specifically altered in the lineage leading to X. tropicalis which inhabits warmer niches. Moreover, the thermal sensitivity of TRPA1 was lower in X. tropicalis than the other species, although the thermal sensitivity of TRPV1 and TRPA1 was not always lower in species that inhabit warmer niches than the species inhabit cooler niches. However, a clear correlation was found in species differences in TRPA1 activity. Heat-evoked activity of TRPA1 in X. borealis and X. laevis, which are adapted to cooler niches, was significantly higher than in X. tropicalis and X. muelleri which are adapted to warmer niches. These findings suggest that the functional properties of heat sensors changed during Xenopus evolution, potentially altering the preferred temperature ranges among species.

动物通过温度感知系统检测环境温度波动，借此搜寻适宜的热环境或逃离有害温度条件。因此，温度感知的演化变化可能在生态位选择中发挥了关键作用。爪蟾属（Xenopus）物种因具有广泛的纬度和海拔分布范围，成为研究温度感知与生态位选择之间关联的理想模型。本研究对亲缘关系较近的四种爪蟾物种（北方爪蟾X. borealis、穆勒爪蟾X. muelleri、非洲爪蟾X. laevis以及热带爪蟾X. tropicalis）的神经元热感受器瞬时受体电位香草酸亚型1（TRPV1）和瞬时受体电位锚蛋白亚型1（TRPA1）进行了比较分析，以阐明其功能演化历程，并评估这些受体的功能差异是否与各物种的热生态位选择相关。对四种现存爪蟾的TRPV1进行比较，并重构其祖先TRPV1序列后发现，栖息于温热生态位的热带爪蟾X. tropicalis所在支系中，TRPV1对反复热刺激的响应发生了特异性改变。此外，热带爪蟾X. tropicalis的TRPA1热敏感性低于其他物种；不过，栖息于温热生态位的物种，其TRPV1和TRPA1的热敏感性并不总是低于栖息于较凉生态位的物种。但在TRPA1活性的物种差异中，却存在明确的相关性：适应较凉生态位的北方爪蟾X. borealis与非洲爪蟾X. laevis，其TRPA1的热激发活性显著高于适应温热生态位的热带爪蟾X. tropicalis和穆勒爪蟾X. muelleri。上述研究结果表明，爪蟾演化过程中热感受器的功能特性发生了改变，这可能导致各物种的偏好温度范围出现分化。