Laboratorio de Geomorfología y Cuaternario, CADIC, Ushuaia, Argentina.
Instituto de Ciencias Polares, Ambiente y Recursos Naturales, Universidad Nacional de Tierra del Fuego, Ushuaia, Argentina.
Commun Biol. 2021 Feb 9;4(1):176. doi: 10.1038/s42003-021-01701-5.
A major climate shift took place about 40 Myr ago-the Middle Eocene Climatic Optimum or MECO-triggered by a significant rise of atmospheric CO concentrations. The biotic response to this MECO is well documented in the marine realm, but poorly explored in adjacent landmasses. Here, we quantify the response of the floras from America's southernmost latitudes based on the analysis of terrestrially derived spores and pollen grains from the mid-late Eocene (~46-34 Myr) of southern Patagonia. Robust nonparametric estimators indicate that floras in southern Patagonia were in average ~40% more diverse during the MECO than pre-MECO and post-MECO intervals. The high atmospheric CO and increasing temperatures may have favored the combination of neotropical migrants with Gondwanan species, explaining in part the high diversity that we observed during the MECO. Our reconstructed biota reflects a greenhouse world and offers a climatic and ecological deep time scenario of an ice-free sub-Antarctic realm.
大约 4000 万年前发生了一次主要的气候转变——中始新世气候最优期（MECO），其由大气 CO2 浓度的显著上升引发。海洋领域对这一 MECO 的生物响应已有充分记录，但相邻陆地区域的研究却很少。在这里，我们根据巴塔哥尼亚南部中晚始新世（约 46-3400 万年前）的陆生孢粉分析，定量研究了来自美洲最南端的植物群的响应。稳健的非参数估计器表明，与 MECO 前和 MECO 后时期相比，巴塔哥尼亚南部的植物群在 MECO 期间的平均多样性高出约 40%。高浓度的大气 CO2 和不断升高的温度可能有利于新热带移民与冈瓦纳物种的结合，这部分解释了我们在 MECO 期间观察到的高多样性。我们重建的生物群反映了一个温室世界，并提供了一个无冰的亚南极地区的气候和生态深时场景。
