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© 2016. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Paleoecological studies document the net effects of atmospheric and climate change in a natural laboratory over timescales not accessible to laboratory or ecological studies. Insect feeding damage is visible on well-preserved fossil leaves, and changes in leaf damage through time can be compared to environmental changes. We measured percent leaf area damaged on four fossil leaf assemblages from the Bighorn Basin, Wyoming, that range in age from 56.1 to 52.65 million years (Ma). We also include similar published data from three US sites 49.4 to ~45 Ma in our analyses. Regional climate was subtropical or warmer throughout this period, and the second oldest assemblage (56 Ma) was deposited during the Paleocene–Eocene Thermal Maximum (PETM), a geologically abrupt global warming event caused by massive release of carbon into the atmosphere. Total and leaf-chewing damage are highest during the PETM, whether considering percent area damaged on the bulk flora, the average of individual host plants, or a single plant host that occurs at multiple sites. Another fossil assemblage in our study, the 52.65 Ma Fifteenmile Creek paleoflora, also lived during a period of globally high temperature and pCO2, but does not have elevated herbivory. Comparison of these two sites, as well as regression analyses conducted on the entire dataset, demonstrates that, over long timescales, temperature and pCO2 are uncorrelated with total insect consumption at the ecosystem level. Rather, the most important factor affecting herbivory is the relative abundance of plants with nitrogen-fixing symbionts. Legumes dominate the PETM site; their prevalence would have decreased nitrogen limitation across the ecosystem, buffering generalist herbivore populations against decreased leaf nutritional quality that commonly occurs at high pCO2. We hypothesize that nitrogen concentration regulates the opposing effects of elevated temperature and CO2 on insect abundance and thereby total insect consumption, which has important implications for agricultural practices in today's world of steadily increasing pCO2.

Details

Title
Consequences of elevated temperature and pCO2 on insect folivory at the ecosystem level: perspectives from the fossil record
Author
Currano, Ellen D 1 ; Laker, Rachel 2 ; Flynn, Andrew G 3 ; Fogt, Kari K 2 ; Stradtman, Hillary 2 ; Wing, Scott L 4 

 Departments of Botany and Geology & Geophysics, University of Wyoming, Laramie, Wyoming; Department of Geology and Environmental Earth Science, Miami University, Oxford, Ohio 
 Department of Geology and Environmental Earth Science, Miami University, Oxford, Ohio 
 Department of Geology and Environmental Earth Science, Miami University, Oxford, Ohio; Department of Geology, Baylor University, Waco, Texas 
 Department of Paleobiology, Smithsonian Institution, Washington, District of Columbia 
Pages
4318-4331
Section
Original Research
Publication year
2016
Publication date
Jul 2016
Publisher
John Wiley & Sons, Inc.
e-ISSN
20457758
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2290252391
Copyright
© 2016. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.