Inferring ecological disturbance in the fossil record: A case study from the late Oligocene of Ethiopia
Inferring ecological disturbance in the fossil record: A case study from the late Oligocene of Ethiopia
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DOI：
10.1016/j.palaeo.2011.06.007
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发表时间：
2011-09-01
影响因子：
3
通讯作者：
Tabor, Neil J.
中科院分区：
文献类型：
--
作者：
Currano, Ellen D.;Jacobs, Bonnie F.;Tabor, Neil J.
环境干扰深刻地影响着现代森林群落的结构、组成和多样性。对现代研究的回顾表明，用于描述被子植物化石组合的重要特征，包括叶缘类型、植物形态、植物多样性、昆虫食草性多样性和专化性，以及植物种类间的草食性变异，在演替早期和后期是不同的。因此，包含早期和晚期演替群落的化石植物群序列可能不适合研究气候、纬度或其他变量的长期时间趋势或生物影响。我们在埃塞俄比亚西北部奇尔加盆地的两个同期晚渐新世(27-28 Ma)叶部进行了沉积学、古植物学和昆虫损害分析，以检验演替阶段解释组合之间差异的假设。广河和牛皮化石植物产地在地层上是对等的，相距仅1.5公里，但它们没有共同的植物物种。公牛风箱的沉积结构表明，与构成广河化石单元的单一、平凡的泥岩相比，多期沉积和更受干扰的环境。与广相比，牛风箱的齿缘植物种类比例明显更高，植食性和昆虫食草性物种的危害多样性更低，专门的食草动物危害更少。此外，许多公牛贝壳植物物种的近亲与早期演替森林有关，而广河植物是早期和晚期演替物种的混合体。因此，广州植物区系的生理和生态属性与较成熟的森林群落是一致的，两个植物区系之间的差异强调了从同一地层水平收集多个植物群的重要性，以解释景观水平的生态过程。更具体地说，对热带富含被子植物的化石组合的多样性和取食专门化的准确估计对于充分解决现代热带物种多样性相对较高的起源和持久性以及现代热带非洲和南美洲等区域之间的多样性差异至关重要。(C)2011爱思唯尔B.V.保留所有权利。
Environmental disturbances profoundly impact the structure, composition, and diversity of modern forest communities. A review of modern studies demonstrates that important characteristics used to describe fossil angiosperm assemblages, including leaf margin type, plant form, plant diversity, insect herbivore diversity and specialization, and variation in herbivory among plant species, differ between early and late successional forests. Therefore, sequences of fossil floras that include a mix of early and later successional communities may not be appropriate to study long-term temporal trends or biotic effects of climate, latitude, or other variables.We conducted sedimentological, paleobotanical, and insect damage analyses at two contemporaneous late Oligocene (27-28 Ma) leaf localities in the Chilga Basin, northwest Ethiopia, to test the hypothesis that successional stage explains variation between the assemblages. The Guang River and Bull's Bellow fossil plant localities are stratigraphically equivalent and only 1.5 km apart, but they have no plant species in common. Sedimentary structures at Bull's Bellow suggest multiple episodes of deposition and a more disturbed environment than the single, featureless mudstone that composes the Guang River fossil unit. Bull's Bellow has a significantly higher percentage of plant species with toothed margins, lower plant and insect herbivore damage diversity, and less specialized herbivore damage than Guang. Furthermore, the nearest living relatives of many of the Bull's Bellow plant species are associated with early successional forests, whereas the Guang River plants are a mix of early and late successional species. Thus, the physiological and ecological attributes of the Guang flora are consistent with a more mature forest community, and the differences between the two floras emphasize the importance of collecting multiple floras from the same stratigraphic level in order to account for landscape-level ecological processes. More specifically, accurate estimates of diversity and feeding specialization in tropical, angiosperm-rich fossil assemblages are essential to address adequately the origin and persistence of relatively high species diversity in the modern tropics, and diversity differences between regions such as modem tropical Africa and South America. (C) 2011 Elsevier B.V. All rights reserved.