Department of Biology
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Robert S. Sikes
Associate Professor
Interim Dean
Research and Graduate Studies
(501) 569-8661
(501) 569-3039 (fax)
rssikes@ualr.edu
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Ph.D. (Zoology) 1994 University of Minnesota
M.S. (Zoology) 1991 Memphis State University
B.S. (Biology) 1985 University of Arkansas at Little Rock
Research Interests
Behavioral and Evolutionary Ecology
My academic training is broad and is centered around behavioral
ecology. My research focuses on assessing inter- and intraspecific
patterns of maternal investment as a function of litter size and
environmental stability both at the level of individuals and
populations. I am especially interested in how these relationships
are shaped by the energetic requirements of reproduction. Why
animals produce litters or clutches of a certain size has long
interested naturalists, but most previous work has centered on
evolution of an optimum litter size rather than litter size
variability. The approach I have taken in addressing this question
is to look first at how variability might or might not be favored
by selection. Such variability provides the raw material from which
optimal litter size for a specific set of conditions is derived,
and this variability is influenced strongly by environmental
stability. Because reproduction represents such an enormous
energetic commitment for female mammals, the tactical allocation
of resources in response to proximate environmental cues, either
by behavioral or physiological adjustments, can immediately and
profoundly affect fitness.
A second area of interest is behavioral and physiological tactics
and strategies used to balance energy budgets. This work has
focused primarily on captive giant pandas both in the US and in
China. Evaluation of energetic questions has include calorimetric
analyses of samples from digestibility trials and remote detections
of physiological indices.
Students in my lab are given a free rein to determine their own
research direction. Previous graduate students have explored
energetic and behavioral questions, metabolic depression in giant
pandas, and communication in grasshopper mice and pocket gophers.
Communication work performed by students has included both vocal
and chemical components.
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Courses Taught
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BIOL 7310 Experimental Design
BIOL 7311 Behavioral Ecology
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Recent Publications
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DeVries, M. S. and R. S. Sikes. (In press) Vocalizations of a North American subterranean rodent, Geomys breviceps. Bioacoustics.
Gannon, W. L., R. S. Sikes, and the Animal Care and Use Committee of the American Society of Mammalogists. 2007. Guidelines of the American Society of Mammalogists for the use of wild mammals in research. Journal of Mammalogy. 88:809-823.
Sikes, R. S. 2007. Energetic efficiency of reproduction may constrain litter size in northern grasshopper mice. Ecoscience. 14:357-361.
Sims, J. A. J. L. Parsons, H. A. Bissell, R. S. Sikes, J. R. Ouellette, and B. J. Rude. 2007. Determination of bamboo-diet digestibility and fecal output by giant pandas. Ursus. 18:38-45.
White, S. C., D. W. Clark, C. D. Day, and R. S. Sikes. 2007. Variation in digestive efficiency of captive North American river otters (Lontra canadensis) on various diets. Zoo Biology, 26:41-50.
Sikes, R. S. 2007. Facultative adjustment of sex ratios in rodents. Pp. 129-138 In Rodent Societies (J. O. Wolff and P. Sherman, eds). Oxford University Press, MA.
Sikes, R. S. and T. G. Finley. 2004. Vocalizations of northern grasshopper mice. Pp. 419-422 in: (M. Bekoff, ed.) Encyclopedia of Animal Behavior. Greenwood Press, CT.
Sikes, R. S., J. R. Tester, and B. Thoma. Mammals of Itasca State Park. 2003. Minnesota Department of Natural Resources.
Andersen, D. E., T. R. Laurion, J. R. Cary, R. S. Sikes, M. A. McLeod, and E. M. Gese. 2002. Ecology of swift fox in southeastern Colorado. Proceedings of the Swift Fox Symposium (M. A. Sovada and L. Carbyn, eds) pp. 139-147.
Birney, E. C. G. E. Nordquist, R. S. Sikes, and J. A. Monjeau. 2000. Small mammal assemblage composition in Minnesota: Ecogeographic versus ecological influences. For Reflections of a Naturalist: Papers Honoring Professor Eugene D. Fleharty. Fort Hays Studies Special Issue #1: 95-124.
Garshelis, D. L., R. S. Sikes, D. E. Andersen, and E. C. Birney. 1999. Landowner's perceptions of crop damage and management practices related to black bears in east-central Minnesota. Ursus, 11:219-224.
Kramer, K. M., E. C. Birney, J. A. Monjeau, and R. S. Sikes. 1999. Phyllotis xanthopygus. Mammalian Species. 617:1-7
Siems, D. P. and R. S. Sikes. 1998. Tactical allocation to growth and reproduction in response to temporal variation in food supply. Environmental Biology of Fishes, 53:319-329.
Sikes, R. S. and H. Ylönen. 1998. Considerations of optimal litter size in mammals. Oikos, 83:452-465.
Monjeau, J. A., E. C. Birney, L. Ghermandi, R. S. Sikes, L. Margutti, and C. J. Phillips. 1998. Plants, small mammals, and the hierarchical landscape classifications of Patagonia. Landscape Ecology, 13:285-306.
Sikes, R. S. 1998. Tradeoffs between offspring quality and litter size: Differences do not persist into adulthood. Journal of Mammalogy, 79:1143-1151.
Sikes, R. S. 1998. Unit Pricing: Economics and the evolution of litter size. Evolutionary Ecology, 12:179-190. Sikes, R. S., J. A. Monjeau, E. C. Birney, C. J. Phillips, and J. Hillyard. 1997. Chromosomal, molecular, and morphological divergence in Eligmodontia. Zeitschrift für Säugetierkunde, 62:265-280.
Sikes, R. S. 1996. Tactics of maternal investment of grasshopper mice in response to postnatal restriction of food. Journal of Mammalogy, 77:1092-1101.
Sikes, R. S. 1996. Effects of maternal nutrition on post-weaning growth in two North American rodents. Behavioral Ecology and Sociobiology, 38:303-313.
Sikes, R. S. 1995. Maternal response to resource limitation in eastern woodrats. Animal Behaviour, 49:1551-1558
Sikes, R. S. 1995. Costs of lactation and optimal litter size in northern grasshopper mice (Onychomys leucogaster). Journal of Mammalogy, 76:348-357.
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Invited Seminars
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Energy conservation in a carnivore turned vegetarian. Oklahoma State University. September, 2007.
Energy balance in giant pandas. University of Memphis. March, 2007.
Energetic constraints on size and number of offspring. Symposium on Life Histories: the basics revisited. IX International Mammalogical Congress, Sapporo, Japan, 31 July-5 August, 2005.
Energy correlates of reproduction in mammals. UALR Biosciences Seminar series. 31 January, 2005
Use of wild mammals in research. Invited speaker and panelist. On a workshop on use of wildlife in research sponsored by OLAW, the NSF, and the University of Alaska, Fairbanks, 13-15 May, 2004, Fairbanks, Alaska.
Co-convener, Symposium on Mammalian Reproductive Strategies. Third European Mammal Congress. 30 May - 4 June 1999. Jyväskylä, Finland.
Experimental Approaches and Limitations to Questions of Maternal Investment. Symposium on Experimental Testing of Hypotheses in Mammalian Behavioral Ecology. Seventh International Theriological Congress. September 1997. Acapulco, México.
Energetics of Lactation and the Evolution of Litter Size. International Symposium on Mating Systems and Reproductive Costs. January 1996. Jyväskylä, Finland.
Maternal Investment Under Nutritional Stress: Testing Hypotheses and Assumptions. International Symposium on Mating Systems and Reproductive Costs. January 1996. Jyväskylä, Finland.
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Research Funding
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The effects of litter size and litter size manipulations
on energetic cost of lactation in northern grasshopper mice - National
Science Foundation
Status and Distribution of the Desert Shrew, Notiosorex crawfordi, in
Arkansas - Arkansas Game and Fish Commission
The role of energetics in maintenance and breeding of the giant panda -
Memphis Zoological Association
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Professional Memberships
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American Society of Mammalogists
American Association for the Advancement of Science
Sigma Xi
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