Wednesday, August 10, 2016
ESA Exhibit Hall, Ft Lauderdale Convention Center
Dylan R. Kent1, Joshua S. Lynn1, Scott L. Collins1, Steven Pennings2 and Jennifer A. Rudgers1, (1)Department of Biology, University of New Mexico, Albuquerque, NM, (2)Biology and Biochemistry, University of Houston, Houston, TX
Background/Question/Methods The hypothesis that plant-herbivore interactions are strongest toward the equator has been pervasive in ecology. While some extensive studies have documented a latitudinal gradient in herbivore damage, many recent studies have produced conflicting results, suggesting that this pattern may not be ubiquitous, and that adjustment to current theory may be warranted. Here, we assessed herbivory on five dominant rangeland grass species of the Great Plains of North America across three, replicate latitudinal gradients, in order to address the question: is herbivory strongest at low latitude as a general biogeographical pattern? By additionally sampling a cross-site Extreme Drought in Grassland Experiment (EDGE), which imposed a 66% event size reduction during the growing season, we assessed potential effects of climate change on patterns in herbivory. We also collected site-level data on abiotic factors (e.g. climate, soil quality) as alternative factors that may explain geographic variation in herbivory.
Results/Conclusions
Results showed that herbivore damage was not greatest at low latitude as a general trend across all focal species, and that latitudinal patterns in herbivory are species-dependent for dominant range grasses of North America. This suggests that generalizations cannot easily be made across related taxa. We observed the expected gradient in two of five focal species, and no latitudinal pattern in the remaining three species. Results from the EDGE experiment showed an increase in the amount of damage under chronic drought as a general pattern across all species data, but not in the occurrence of herbivory. Furthermore, responses to drought were species-specific, which could shift the balance of competition among dominant range grasses in North American grassland ecosystems in the future. Our findings suggest that climate change may exacerbate fitness declines for some plant species through amplified herbivory.
