Diverse Fossil Floras from the Paleogene of Patagonia, Argentina: Origins of High Plant and Insect Diversity in South America

野生热带南美洲拥有世界上最丰富的物种，拥有许多陆地动植物种群，使该地区成为保护的首要任务。然而，人们对这种特殊生物多样性的历史知之甚少，因为南美洲北部的岩石暴露受到森林覆盖和深度风化的限制。巴塔哥尼亚中纬度地区的古新世和早始新世化石植物群是解决这一问题的宝贵资源。这些组合很好地暴露在现代沙漠露头中，代表了在全球温暖时期存在的扩大的新热带森林南部的潮湿亚热带植被。其中最壮观的巴塔哥尼亚植物群之一来自拉古纳德尔亨科(L H)，这是阿根廷丘布特省的一个始新世早期(5200万年前)遗址，其出色的保存与北美最著名的始新世植物群相当，如弗洛里桑特和共和国。在早期的工作中，研究人员从不到5000个样本中恢复了155多个植物物种。在这些实体中，只有不到25%是以前已知的。根据样本大小进行调整，这大大超过了其他任何地区始新世植物群的丰富度，但仍存在发现更多物种的潜力。在这些植物化石上，保存着任何新生代植物中保存完好的、由昆虫介导的叶片损害的最高多样性，包括各种以前未记录的专门取食的例子，如虫胆和地雷。这些早期的结果支持这样一种假设，即南美洲的超多样性通常被归因于最近200-1000万年的事件，可能具有更古老的历史。这项研究将研究植物多样性、植物和昆虫系统学，以及植物与昆虫的关联性。这两个植物群分别是始新世(里约内格罗省的里奥皮奇卢夫)和古新世(萨拉曼卡，楚布特省)。要解决的主要问题包括：(1)在巴塔哥尼亚古近纪的大片地区是否存在高度的植物和昆虫食性多样性？(2)从古新世到始新世，随着全球变暖，是否存在植物和昆虫的多样性？(3)植物群和它们的食虫动物确切地说，新热带和“澳大利亚”的亲缘关系是什么，这些亲缘关系对于理解现代生物群的重要性是什么？预计这项工作将在学生培训、国际合作和成果传播方面产生几个有益的影响。学生参与将是这项研究从实地到出版的所有阶段的核心，包括两名女性和一名男性阿根廷博士生的主要参与。该项目是在阿根廷科学机会减少的情况下，美国和阿根廷不同的专家之间的国际合作。主要清单数据将通过专题处理、数据集的因特网出版以及将标本存放在阿根廷的寄主储存库而永久提供给研究界。对南美洲生物多样性深厚历史的阐释预计将对今天南美洲的研究和保护工作产生影响。

0345750WilfTropical South America has the highest species richness in the world for many groups of terrestrial plants and animals, making this region a top priority for conservation. However, the history of this exceptional biodiversity is poorly understood because rock exposures in northern South America are limited by forest cover and deep weathering. Paleocene and early Eocene fossil floras from middle latitudes of Patagonia are invaluable resources for addressing this problem. Well exposed in modern desert outcrops, these assemblages represent humid subtropical vegetation from the southern reaches of the expanded Neotropical forests that existed during a globally warm time period. One of the most spectacular Patagonian floras comes from Laguna del Hunco (LH), an early Eocene (52 million years ago) site in Chubut Province, Argentina with outstanding preservation equal to the most famous North American Eocene floras, such as Florissant and Republic. In earlier efforts, the investigators recovered more than 155 plant species from fewer than 5,000 specimens. Fewer than 25% of these entities were previously known. Adjusted for sample size, this significantly exceeds the richness of Eocene floras from any other region, yet the potential exists for many more species to be found. On these fossil plants is preserved the highest diversity of well-preserved, insect-mediated leaf damage of any Cenozoic flora, including diverse and previously unrecorded examples of specialized feeding such as galls and mines. These early results support the hypothesis that South American hyperdiversity, usually attributed to relatively recent events of the last 2-10 million years, may have a considerably more ancient history. This study will examine floral diversity, plant and insect systematics, and plant-insect associations at LH and two other floras, one Eocene (Rio Pichileufu, Rio Negro Province) and one Paleocene (Salamanca, Chubut Province). Major questions to be addressed include: (1) Did high plant and insect-feeding diversity exist over a broad area of Paleogene Patagonia? (2) Was there a diversification of plants and insects from the Paleocene to the Eocene with global warming as seen elsewhere in the world? (3) What are the precise Neotropical and "Australasian" affinities of the floras and their insect herbivores, and what is the importance of these affinities for understanding modern biotas? The work is expected to have several beneficial impacts with regard to student training, international collaboration, and dissemination of results. Student participation will be central to all phases of the research from field to publication, including the major involvement of two female and one male Argentine doctoral students. The project is an international collaboration among diverse U.S. and Argentine specialists at a time of reduced scientific opportunity in Argentina. Primary inventory data will be permanently available to the research community through monographic treatments, Internet publication of data sets, and the deposition of specimens in the Argentine host repository. Illumination of the deep history of South American biodiversity is expected to have impacts on research and conservation efforts in South America today.