Endemism in Wyoming plant and insect herbivore communities during the early Eocene hothouse
Endemism in Wyoming plant and insect herbivore communities during the early Eocene hothouse
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DOI：
10.1017/pab.2019.18
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发表时间：
2019-06
期刊：
影响因子：
2.7
通讯作者：
E. Currano;E. Pinheiro;R. Buchwaldt;W. Clyde;I. Miller
中科院分区：
文献类型：
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作者：
E. Currano;E. Pinheiro;R. Buchwaldt;W. Clyde;I. Miller
始新世早期温暖、稳定、无冰的气候条件使我们能够在与今天截然不同的气候条件下研究生态系统功能和宏观生态模式。它还提供了对未来可能发生的事情的见解，因为人为的二氧化碳释放将地球推向类似的温室条件。在温室间隔期间研究植物-昆虫食草性食物网是有必要的，因为它们占了非微生物陆地生物多样性的大部分。本文报道了怀俄明州中部风河盆地两个洪泛区的新植物和昆虫食草动物损害普查数据，一个位于盆地边缘（WRE）的Aycross组（50-48.25 Ma），另一个位于盆地内部（WRI）的风河组。WRI遗址在地层上接近一种新定年为52.416±0.016/0.028/0.063 （2σ）的火山灰。我们将风河流域的植物群与邻近Bighorn （BH）盆地52.65 Ma洪泛平原植物群的已发表数据进行了比较，发现只有5.6%的植物类群出现在三个地点，大约10%的植物类群出现在两个盆地。不同的植物区系支持不同种类的食草昆虫，这是由叶片损伤所记录的。相对低多样性的BH区系昆虫伤害多样性最高，这与昆虫食草性多样性追随植物多样性的假设相反。WRE区系的独特性可能是由于其年龄较年轻和重建的古温度较低，但WRI区系和BH区系的这些因素几乎相同。特定地点的微环境因素无法在较长时间内轻易测量，可能是造成这些差异的原因。另外，两个盆地之间的Owl Creek山脉可能为栖息在盆地内部的嗜热生物提供了一个强大的屏障，这支持了Janzen的假设，即热带环境中的山口看起来更高。
Abstract The warm, equable, and ice-free early Eocene Epoch permits investigation of ecosystem function and macro-ecological patterns during a very different climate regime than exists today. It also provides insight into what the future may entail, as anthropogenic CO2 release drives Earth toward a comparable hothouse condition. Studying plant–insect herbivore food webs during hothouse intervals is warranted, because these account for the majority of nonmicrobial terrestrial biodiversity. Here, we report new plant and insect herbivore damage census data from two floodplain sites in the Wind River Basin of central Wyoming, one in the Aycross Formation (50–48.25 Ma) at the basin edge (WRE) and the second in the Wind River Formation in the interior of the basin (WRI). The WRI site is in stratigraphic proximity to a volcanic ash that is newly dated to 52.416 ± 0.016/0.028/0.063 (2σ). We compare the Wind River Basin assemblages to published data from a 52.65 Ma floodplain flora in the neighboring Bighorn (BH) Basin and find that only 5.6% of plant taxa occur at all three sites and approximately 10% occur in both basins. The dissimilar floras support distinct suites of insect herbivores, as recorded by leaf damage. The relatively low-diversity BH flora has the highest diversity of insect damage, contrary to hypotheses that insect herbivore diversity tracks floral diversity. The distinctiveness of the WRE flora is likely due to its younger age and cooler reconstructed paleotemperature, but these factors are nearly identical for the WRI and BH floras. Site-specific microenvironmental factors that cannot be measured easily in deep time may account for these differences. Alternatively, the Owl Creek Mountains between the two basins may have provided a formidable barrier to the thermophilic organisms that inhabited the basin interiors, supporting Janzen's hypothesis that mountain passes appear higher in tropical environments.