title: Insect herbivory fluctuations through geological time.
abstract: Arthropods and land plants are the major macroscopic sources of biodiversity on the planet. Knowledge of the organization and specialization of plant-herbivore interactions, such as their roles in food webs is important for understanding the processes for maintaining biodiversity. A limited number of studies have examined herbivory through geological time. The most have analyzed localities from one restricted interval within a geological period, or a time transition such as the Paleocene-Eocene boundary interval. In the present study, we analyzed the frequency of herbivory and density of damage type (DT) from the Middle Devonian to the early Miocene. The data were compiled from literature sources and focused on studies that describe occurrences of leaves with DTs indicating herbivore consumption as a proportion of the total number of leaves analyzed. The data were standardized based on the DT categories in the Damage Type Guide, and the age of each locality was updated based on the most recent geochronological standard and expressed in millions of years. Temperature and geological age were the best descriptors of the variation in herbivory frequency, which tended to increase at higher temperatures. Two models were equivalent to explain DT density: the interaction between CO2levels and geological age, and O2levels and geological age had the same predictive power. The density of DT tended to increase with higher content of atmospheric CO2and O2compared to modern values. The frequency of herbivory and the density of DTs appear to be influenced by long-term atmospheric variables.
authors.affiliation: Departamento de Paleontologia e Estratigrafia, Laboratório de Paleobotânica, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves 9500, CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Esther R S
authors.initials: ERS
authors.lastname: Pinheiro
authors.affiliation: Departamento de Paleontologia e Estratigrafia, Laboratório de Paleobotânica, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves 9500, CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Roberto
authors.initials: R
authors.lastname: Iannuzzi
authors.affiliation: Laboratório de Ecologia Filogenética e Funcional, Centro de Ecologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Leandro D S
authors.initials: LDS
authors.lastname: Duarte
mesh_terms: D000818:Animals; D001181:Arthropods; D044822:Biodiversity; D005075:Biological Evolution; D005844:Geology; D060434:Herbivory; D007313:Insecta / Q000502:physiology*; D018515:Plant Leaves
keywords: carbon dioxide; density of damage types; insect herbivory frequency; oxygen; temperature