翼龍的飛行效率持續提升了1.5億年
作者：
小柯機器人發布時間：2020/10/30 15:06:07
英國林肯大學Stuart Humphries、雷丁大學Chris Venditti等研究人員合作發現，翼龍的飛行效率持續提升了1.5億年。這一研究成果於2020年10月28日在線發表在國際學術期刊《自然》上。
研究人員描述了翼龍適應一種新運動方法的進化動力學。已知最早的翼龍開始了飛行，隨後似乎已經成為有能力和有效率的飛行者。然而，在運動形式之間的過渡（從陸地到空地），通過施加高能量負擔來挑戰了早期翼龍，因此需要飛行才能提供一些補償性的適應益處。使用系統發育統計方法和生物物理模型，再結合化石記錄中的信息，研究人員檢測到自然選擇的進化信號，該信號在數百萬年的時間內提高了飛行效率。結果表明，在飛行出現後，效率仍有相當大的提高空間。但是，在展現出巨大形態的進化枝Azhdarchoidea中，研究人員檢驗了對飛行依賴減少的假設，並找到了降低進化枝對飛行效率選擇的證據。這個方法提供了一個藍圖，可以比以往更細緻的程度客觀地研究地質時期內功能和能量的變化。
據了解，生物多樣性的長期積累已因非同尋常的進化過渡而中斷，從而使生物能夠利用新的生態機會。中生代飛行爬行動物（翼龍）是這種過渡的產物，它們在天空中佔據了1.5億多年的歷史。翼龍的祖先很小，可能是兩足動物早期的恐龍，它們當然很適合陸地運動。在三疊紀早期（約2.45億年前），翼龍與恐龍祖先分開。然而，翼龍的第一個化石可追溯到2500萬年後的三疊紀晚期。因此，在沒有翼龍化石的情況下，很難研究飛行在這一群體中是如何演化的。
附：英文原文
Title: 150 million years of sustained increase in pterosaur flight efficiency
Author: Chris Venditti, Joanna Baker, Michael J. Benton, Andrew Meade, Stuart Humphries
Issue&Volume: 2020-10-28
Abstract: The long-term accumulation of biodiversity has been punctuated by remarkable evolutionary transitions that allowed organisms to exploit new ecological opportunities. Mesozoic flying reptiles (the pterosaurs), which dominated the skies for more than 150 million years, were the product of one such transition. The ancestors of pterosaurs were small and probably bipedal early archosaurs1, which were certainly well-adapted to terrestrial locomotion. Pterosaurs diverged from dinosaur ancestors in the Early Triassic epoch (around 245 million years ago); however, the first fossils of pterosaurs are dated to 25 million years later, in the Late Triassic epoch. Therefore, in the absence of proto-pterosaur fossils, it is difficult to study how flight first evolved in this group. Here we describe the evolutionary dynamics of the adaptation of pterosaurs to a new method of locomotion. The earliest known pterosaurs took flight and subsequently appear to have become capable and efficient flyers. However, it seems clear that transitioning between forms of locomotion2,3—from terrestrial to volant—challenged early pterosaurs by imposing a high energetic burden, thus requiring flight to provide some offsetting fitness benefits. Using phylogenetic statistical methods and biophysical models combined with information from the fossil record, we detect an evolutionary signal of natural selection that acted to increase flight efficiency over millions of years. Our results show that there was still considerable room for improvement in terms of efficiency after the appearance of flight. However, in the Azhdarchoidea4, a clade that exhibits gigantism, we test the hypothesis that there was a decreased reliance on flight5,6,7 and find evidence for reduced selection on flight efficiency in this clade. Our approach offers a blueprint to objectively study functional and energetic changes through geological time at a more nuanced level than has previously been possible.
DOI: 10.1038/s41586-020-2858-8
Source: https://www.nature.com/articles/s41586-020-2858-8