良性環境促進耐熱性狀多樣性

Abstract

研究熱特徵對於了解物種對氣候變化的脆弱性至關重要。然而，人們對環境條件、物種層面的熱性狀適應 (thermal trait adaptation) 和群聚 (assemblage) 層面的功能性狀多樣性 (functional traits diversity) 之間的關係知之甚少。在此，我們利用大型野外實驗，在中國、臺灣和馬來西亞山區以水浴槽實際測量蛾類的耐受溫度極限，同時沿海拔放置Robinson式陷阱收集物種的海拔分布資料，亦使用iButton紀錄當地的微氣候資料，最後還建立了一個基於個體的模型。我們總共收集了653種蛾的熱和形態特徵，以研究環境如何影響物種及群聚層面的熱適應和熱與形態性狀多樣性之間的關係。我們的研究結果表明，與經典的氣候變異度假說 (climate variability hypothesis) 相反，我們沒有發現物種的熱適應範圍隨著氣候變異度的增加而增加。相反，耐寒的物種不耐高溫，耐高溫的物種不耐寒，從而支持了權衡假說 (trade-off hypothesis)。在群聚層面，我們發現較熱環境的群聚具有較高的熱功能多樣性。這是因為在較熱環境的群聚中，物種耐寒性和耐熱性之間的權衡較弱，可能是由於較熱環境的環境限制較少。因此，我們的結果支持有利性假說 (favorability hypothesis)。最後，我們的結果還表明，低海拔和低緯度地區的群聚除了具有較高的物種多樣性外，還具有較高的熱與形態性狀多樣性，因此需要優先關注及保護。

Studying thermal traits are crucial for understanding the species vulnerability to climate change. However, little is known about the relationships among environmental condition, thermal trait adaptation at species level and thermal trait diversity at assemblage level. Here, we used large-scale field experiments to test the critical thermal limits of moths by using water baths in mountain areas of China, Taiwan, and Malaysia. We placed Robinson’s traps along the elevation to collect species’ elevation distribution data, and used iButton to record local microclimate data. Moreover, we constructed an individual-based model. We collected thermal and morphological traits of 653 species of moths to investigate how environments affect the relationship between thermal adaptation and thermal trait diversity at the species and assemblage level. Our results showed that in contrast to the classical climate variability hypothesis, we did not find the thermal tolerance range of species increased with increasing climate variability. On the contrary, cold-tolerant species are less heat-tolerant and vice versa, thus supporting the trade-off hypothesis. At the assemblage level, we found that the assemblages in the hotter environments have higher thermal functional diversity. This is because the trade-off between species’ cold and warm tolerance is weaker in assemblages in the warmer environments, likely due to less environmental constraints in the warmer environments. Therefore, our results support the favorability hypothesis. Ultimately, our results also suggest that assemblages at low elevations and latitudes have high functional diversity in addition to high species diversity, which requires priority attention for conservation.