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

0345750 Wilf热带南美洲拥有世界上最丰富的陆生植物和动物物种，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，因为南美洲北方的岩石暴露受到森林覆盖和深层风化的限制。巴塔哥尼亚中纬度地区的古新世和始新世早期植物群化石是解决这一问题的宝贵资源。在现代沙漠露头暴露良好，这些组合代表了湿润的亚热带植被，从南部延伸的扩大新热带森林，存在于全球温暖的时间段。最壮观的巴塔哥尼亚植物群之一来自拉古纳德尔洪科（LH），这是阿根廷丘布特省的一个早始新世（5200万年前）遗址，其杰出的保存与最着名的北美始新世植物群（如弗洛里森特和共和国）相当。在早期的努力中，研究人员从不到5,000个标本中恢复了超过155种植物。这些实体中只有不到25%是以前已知的。根据样本量调整后，这一数量远远超过了其他任何地区始新世植物群的丰富程度，但仍有可能发现更多的物种。在这些植物化石上，保存着任何新生代植物群中保存最丰富的、由昆虫介导的叶片损伤，包括各种各样的、以前没有记录的专门取食的例子，如虫瘿和矿井。这些早期的结果支持了这样的假设，即南美洲的高度多样性，通常归因于最近的事件，在过去的200万至1000万年，可能有一个相当古老的历史。本研究将研究植物多样性，植物和昆虫系统学，植物昆虫协会在LH和其他两个植物群，一个始新世（里约Pichileufu，里奥内格罗省）和一个古新世（萨拉曼卡，丘布特省）。主要问题包括：（1）高植物和昆虫取食的多样性存在于广泛的地区的古近纪巴塔哥尼亚？(2)从古新世到始新世，随着全球变暖，植物和昆虫的多样性是否与世界其他地方一样？(3)新热带区系和“澳大拉西亚”区系与它们的食草昆虫之间的亲缘关系是什么？这些亲缘关系对理解现代生物多样性有什么重要意义？ 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若干有益影响。学生的参与将是从实地到出版的所有研究阶段的核心，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，美国和阿根廷不同专家之间的国际合作。通过专题处理、在互联网上公布数据集以及将标本存放在阿根廷主储存库，研究界将永久获得原始清单数据。南美生物多样性的深厚历史的照明预计将对今天在南美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.