Abstract Detail

Ecology

Pittenger, Madison [1], Maricle, Keri [2], Baer, Sara [3], Johnson, Loretta [4], Maricle, Brian [5].

Herbivory Preferences Among Ecotypes of Big Bluestem (Andropogon gerardii).

Big bluestem (Andropogon gerardii), a dominant prairie grass, exhibits a wide distribution with several genetically distinct ecotypes. Each ecotype adapts to abiotic and biotic factors within its environment. These adaptations may prove more or less desirable to herbivores in the area. For instance, plants adapted to areas with greater rainfall tend to grow larger than those adapted to drier conditions. However, wetter conditions might result in greater herbivore pressure, so ecotypes adapted to wetter conditions might have evolved greater herbivore defense mechanisms; therefore, a trade-off may exist between drought resistance and herbivore resistance. We hypothesized herbivores would display a preference for plants adapted to drier conditions. We tested this with feeding preference trials involving grasshoppers and leaves from five ecotypes of A. gerardii that represented plants adapted to wet and dry conditions. Scans of leaves before and after herbivory trials indicated 56 to 74 percent of leaf area remained, with the more mesic ecotypes being favored by herbivores. We also hypothesized that leaves with more tannins would be less preferable to herbivores. This was tested with measures of leaf tannin concentration from five ecotypes of A. gerardii from four common gardens across a precipitation gradient. Leaf tannin concentrations ranged from 0.0 to 5.5% of leaf dry mass, and were different among both sites and ecotypes, indicating environmental and genetic influences on leaf tannin concentration. More mesic ecotypes had lower tannin concentrations and were preferred by herbivores, indicating ecotypes of A. gerardii are responsive to environmental factors involving herbivory.

1 - Fort Hays State University, Department of Biological Sciences, 600 Park St., Hays, KS, 67601, USA
2 - Fort Hays State University, Department Of Biological Sciences, 600 Park Street, Hays, KS, 67601, United States
3 - Southern Illinois University, Plant Biology, 1263 Lincoln Dr, Carbondale, IL, 62901, USA
4 - Kansas State University, Biology, Ackert Hall Rm 232, Manhattan , KS, 66506-4901, United States
5 - Fort Hays State University, Department Of Biological Sciences, 600 Park St., Hays, KS, 67601, United States

Keywords:
herbivory
ecotype
big bluestem
Andropogon gerardii
grasshopper.

Presentation Type: Oral Paper
Session: 2, Ecology Section - Functional Traits and Responses
Location: 104/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 9:15 AM
Number: 2006
Abstract ID:842
Candidate for Awards:Ecological Section Best Undergraduate Presentation Award