College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia.
Naturalis Biodiversity Center, 2300 RA Leiden, Netherlands.
Science. 2018 Oct 5;362(6410):72-75. doi: 10.1126/science.aas8788.
Differentiating between ancient and younger, more rapidly evolved clades is important for determining paleoenvironmental drivers of diversification. Australia possesses many aridity-adapted lineages, the origins of which have been closely linked to late Miocene continental aridification. Using dental macrowear and molar crown height measurements, spanning the past 25 million years, we show that the most iconic Australian terrestrial mammals, "true" kangaroos (Macropodini), adaptively radiated in response to mid-Pliocene grassland expansion rather than Miocene aridity. In contrast, low-crowned, short-faced kangaroos radiated into predominantly browsing niches as the late Cenozoic became more arid, contradicting the view that this was an interval of global browser decline. Our results implicate warm-to-cool climatic oscillations as a trigger for adaptive radiation and refute arguments attributing Pleistocene megafaunal extinction to aridity-forced dietary change.
区分古老和年轻、进化更快的分支对于确定多样化的古环境驱动因素很重要。澳大利亚拥有许多适应干旱的谱系，其起源与中新世晚期的大陆干旱化密切相关。利用过去 2500 万年的牙齿宏观磨损和臼齿冠高测量，我们表明，澳大利亚最具代表性的陆地哺乳动物“真正的”袋鼠（Macropodini）是为了适应中新世草原扩张而不是上新世干旱而适应性辐射的。相比之下，低冠、短面袋鼠在新生代晚期变得更加干旱时，辐射到以食草为主的生态位，这与认为这是一个全球食草动物减少的时期的观点相矛盾。我们的研究结果表明，温暖到凉爽的气候波动是适应性辐射的触发因素，并驳斥了将更新世巨型动物灭绝归因于干旱导致的饮食变化的观点。
