Is adaptation to climate change really constrained in niche specialists?

Species with restricted distributions make up the vast majority of biodiversity. Recent evidence suggests that Drosophila species with restricted tropical distributions lack genetic variation in the key trait of desiccation resistance. It has therefore been predicted that tropically restricted species will be limited in their evolutionary response to future climatic changes and will face higher risks of extinction. However, these assessments have been made using extreme levels of desiccation stress (less than 10% relative humidity (RH)) that extend well beyond the changes projected for the wet tropics under climate change scenarios over the next 30 years. Here, we show that significant evolutionary responses to less extreme (35% RH) but more ecologically realistic levels of climatic change and desiccation stress are in fact possible in two species of rainforest restricted Drosophila. Evolution may indeed be an important means by which sensitive rainforest-restricted species are able to ...

分布局限的物种构成了生物多样性的绝大多数类群。近期研究证据表明，分布局限的热带果蝇属（Drosophila）物种在耐脱水性这一关键性状上缺乏遗传变异。因此有学者预测，热带分布受限物种应对未来气候变化的进化响应能力将受到限制，且面临更高的灭绝风险。然而，此类评估均采用了极端强度的干燥胁迫（相对湿度低于10%，RH），其严苛程度远超未来30年气候变化情景下湿润热带地区的预期变化幅度。本研究显示，针对强度更低（35% RH）但更符合生态学现实的气候变化与干燥胁迫水平，两种热带雨林分布局限的果蝇属（Drosophila）物种实际上能够产生显著的进化响应。事实上，进化或许正是敏感的热带雨林分布局限物种得以……的重要途径。