Citation
Using Stable Isotope Ratios To Evaluate Seasonal Dietary Breadth In Oryzomys Palustris Sanibeli

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Title:
Using Stable Isotope Ratios To Evaluate Seasonal Dietary Breadth In Oryzomys Palustris Sanibeli
Series Title:
19th Annual Undergraduate Research Symposium
Creator:
Seelig, Alexandra
Language:
English
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Undetermined

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Subjects / Keywords:
Center for Undergraduate Research
Center for Undergraduate Research
Genre:
Conference papers and proceedings
Poster

Notes

Abstract:
The Sanibel Island rice rat (SIRR; Oryzomys palustris sanibeli) is a subspecies marsh rice rat endemic to Sanibel Island, currently listed as a Species of Special Concern in the state of Florida. Rice rats inhabit Sanibel’s interior freshwater marshes and exterior mangrove swamps, and seasonal movement between these areas is presumed. I examined stable isotope ratios (13C/12C and 15N/14N) of SIRR guard hair samples and samples of potential diet items to determine the influence of seasonality (summer or winter) and habitat utilization on trophic level and niche breadth. I used Levene’s test for homogeneity of variance to test hypotheses regarding whether SIRR dietary niche breadth varied seasonally. Analysis showed that dietary niche breadth partially varied between summer and winter samples (13C/12C p=0.068, 15N/14N p=0.018), showing that SIRR diet was more diverse during summer flood periods than during dry winter periods. Their dietary isotopic ratios were found to partly overlap with that of an animal prey base (13C/12C p=0.065,15N/14N p=0.042), but showed no overlap with a plant prey base (13C/12C p=0.001, 15N/14N p=0.01). These findings increase SIRR rank within the food web above that of primary consumers. ( en )
General Note:
Research authors: Alexandra Seelig - University of Florida
General Note:
University Scholars Program
General Note:
Faculty Mentor: The Sanibel Island rice rat (SIRR; Oryzomys palustris sanibeli) is a subspecies marsh rice rat endemic to Sanibel Island, currently listed as a Species of Special Concern in the state of Florida. Rice rats inhabit Sanibel’s interior freshwater marshes and exterior mangrove swamps, and seasonal movement between these areas is presumed. I examined stable isotope ratios (13C/12C and 15N/14N) of SIRR guard hair samples and samples of potential diet items to determine the influence of seasonality (summer or winter) and habitat utilization on trophic level and niche breadth. I used Levene’s test for homogeneity of variance to test hypotheses regarding whether SIRR dietary niche breadth varied seasonally. Analysis showed that dietary niche breadth partially varied between summer and winter samples (13C/12C p=0.068, 15N/14N p=0.018), showing that SIRR diet was more diverse during summer flood periods than during dry winter periods. Their dietary isotopic ratios were found to partly overlap with that of an animal prey base (13C/12C p=0.065,15N/14N p=0.042), but showed no overlap with a plant prey base (13C/12C p=0.001, 15N/14N p=0.01). These findings increase SIRR rank within the food web above that of primary consumers. - Center for Undergraduate Research, University Scholars Program

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University of Florida
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Copyright Alexandra Seelig. Permission granted to University of Florida to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.

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Printing: large Customizing the Content: The placeholders in this formatted for you. placeholders to add text, or click an icon to add a table, chart, SmartArt graphic, picture or multimedia file. T from text, just click the Bullets button on the Home tab. If you need more placeholders for titles, make a copy of what you need and Smart Guides will help you align it with everything else. Want to use your own pictures instead of ours? No problem! Just right Change Picture. Maintain the proportion of pictures as you resize by dragging a corner. Picky or adventurous eaters? Stable isotopes reveal Oryzomys palustris sanibeli diet preferences Introduction The Sanibel Island rice rat (SIRR) is a semiaquatic subspecies endemic to Sanibel Island, Florida 1 Little is known about their ecology, including diet. Diet is important because it determines their trophic level and may be impacted by anthropogenic change. We used stable isotopes to examine relationships between dietary breadth, trophic niche, and seasonality. Methods/Materials Collected SIRR hair samples and diet items from 3 vegetative communities (freshwater marshes, buttonwood shrublands, and mangrove swamps), Analyzed seasonal variance and trophic niche breadth using test of homogeneity of variance 2 Employed generalized linear models to determine if 15 13 C values Investigated whether vegetative community explained 15 13 C values using a Tukey Kramer adjustment for pairwise comparisons 3 Results SIRR isotopic ratios partially overlapped with an animal prey 13 15 N p=0.014), but not at all with a plant 13 15 N p=0.004) Hair 15 N varied significantly between summer and winter (p=0.018; Fig. 3) Vegetative sampling community was significantly correlated with 13 C ratios (Fig. 4) Literature Cited 1 Wolfe, J. L. 1982. Oryzomys palustris Mammalian Species 176:1 5 2 Flaherty, E. A., and M. Ben David. 2010. Overlap and partitioning of the ecological and isotopic niches. Oikos 119:1409 1416 3 Sokal R., and F. Rohlf 1995. Biometry. 3 rd edition. Freedman and Company, New York. 4 Sartore J., Oryzomys palustris sanibeli Conclusions SIRR diet primarily composed of animals instead of vegetation SIRR diet was significantly more diverse in summer months than winter SIRR isotopic ratios indicated little seasonal movement between vegetative communities Objectives Investigate if SIRR dietary breadth varies seasonally Determine SIRR seasonal trophic ranking Determine if isotopic values vary between hair samples collected in different vegetative communities Alexandra L. Seelig 1 Wesley W. Boone, IV 2 and Robert A. McCleery 2 1 University of Florida, Department of Biology, 2 University of Florida, Department of Wildlife Ecology and Conservation Fig. 4: Hair isotopic ratios sorted by the vegetative community in which they were collected. Fig. 2: Oryzomys palustris sanibeli 4 Acknowledgements Honors Program, U.S. Fish and Wildlife Service, and Florida Fish and Wildlife National Wildlife Refuge, Sanibel Captiva Conservation Foundation, the City of Sanibel, and The Sanctuary Golf Club for their collaborative efforts and property access. We thank the Ding Darling Wildlife Society for providing housing throughout our research. Individually, we would like to thank Audrey Albrecht, Jennifer Bernatis Gianna Browne, Joelle Carbonell Nate Caswell, Mark Clark, Jeremy Conrad, Jason Curtis, Sarah Lathrop, Chris Lechowicz Holly Milbrandt Birgie Miller, Morgan, Kyle Sweet, Paul Tritaik and Toni Westland. Fig. 1: Joelle Carbonell Morgan, and Alexandra Seelig, taken while sampling macroinvertebrates Figure 3: Hair sample isotopic rations sorted by the season in which they were collected.