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John Orrock

Research    Publications 

Associate Professor
356 Birge
Office Phone: 608-263-5134

email Ellen         Lab Page


Research Interests

I am interested in behavior, ecological interactions, and how space mediates ecological andevolutionary dynamics. Much of my work occurs where these three themes converge, with a focus on the conservation of terrestrial plants and mammals. Specifically, I am interested in how plant-consumer interactions and predator-prey dynamics affect the prospects for long-term conservation and restoration. To this end, I utilize theoretical, experimental, and observational approaches: I develop theory to understand novel questions of spatial dynamics, I use a strong experimental approach to evaluate existing ecological theory, and I use large-scale observational data to inform conservation and management. I have two main research foci:

Research Focus 1. Spatial mediation of ecological interactions

Apparent competition, vertebrate consumers, and the composition of plant communities. Invasive plants remain one of the most problematic ecological issues of our time, costing billions, usurping habitat for native species, and altering ecosystem function. In collaboration with other researchers, my lab has been evaluating an untested hypothesis of biological invasion: that exotic species gain an advantage indirectly through their effect on native consumers (i.e. apparent competition) rather than through direct competition with native species. I have been particularly interested in understanding the implications of invader-mediated changes in consumer behavior, such as how changes in consumer behavior can dictate the outcome of invasions, change the rate of invasion, generate emergent Allee effects, and have implications for human health.

Spatial controls on the conservation and restoration of flora and fauna in longleaf pine ecosystems.
Longleaf pine communities once stretched from Virginia to Texas and are one of the most diverse ecosystems outside of the tropics; less than 3% remains today. I am part of a mutli-university collaborative project to conduct a large-scale experimental examination of how vertebrate consumers, competitors, and propagule limitation constrain the understory plant communities in longleaf pine savannas. This experiment is replicated in three different states (North Carolina, South Carolina, and Georgia) and embedded within a larger landscape context that makes it possible to understand how historical influences (e.g. agriculture), contemporary land-use practices, and spatial landscape configuration might mediate the ecological forces affecting conservation and restoration (i.e. consumers, competitors, and propagule limitation). Specifically, my role in this collaborative effort is to oversee implementation of experimental treatments to disentangle consumer effects on understory plants.

Large-scale experimental evaluation of conservation corridors.
Corridors are linear strips of habitat that may be promising conservation tools. Yet, examination of corridor studies is often hindered by the difficulty of performing an experiment at large spatial scales. In collaboration with the corridor research group (see, I am working to understand whether conservation corridors are essential components of a viable conservation program, using the first large-scale, replicated experiment designed to test corridor function.

Global variation in the strength of top-down and bottom-up control of grassland communities.
I am one of the 8 core participants and organizers of the Nutrient Network, a unique examination of consumer- and resource-mediated dynamics in grassland dynamics using the same experimental protocol across the world. Conceived by Dr. Eric Seabloom and Dr. Elizabeth Borer at Oregon State University, the nutrient network consists of 60 participants and 45 participating institutions in 10 countries. As one of the core participants, my role in the nutrient network is to spearhead the consumer-mediated portions of the experimental design, to assist in the crafting of NSF proposals, and to implement additional experiments to understand the role of consumers in affecting plant communities.

Research Focus 2. Individual behavior and the consequences of imperfect information

Conservation and anti-predator behavior.
Evidence of the importance of anti-predator behavior in promoting persistence is abundantly clear in island systems, where the introduction of novel predators is cited as one of the most common causes of the extinction of insular prey. I am interested in understanding how rapidly the evolution of anti-predator behavior can occur and how rapidly predator-mediated shifts can propagate through the food web. Recently, I have also been engaged in collaborative work to understand how changes in rodent populations on islands can affect the prevalence of diseases that may also affect humans.

Understanding the pervasive and large-scale consequences of fear. Predators can impact prey dynamics via consuming prey as well as by inducing changes in prey behavior and morphology (i.e. non-consumptive effects). The consequences of non-consumptive effects can rival or exceed those of consumptive effects, and may be much more far-reaching than often thought. I am actively involved in developing theoretical, conceptual, and empirical approaches to understanding how risk mediates spatial dynamics of a wide array of taxa, and how these nonconsumptive effects my subsequently alter the potential for conservation and restoration. In collaboration with Evan Preisser (Univ. Rhode Island), I am conducting a metaanalysis to understand how body size alters the strength of non-consumptive effects.


  • Zoology 101: Animal Biology
  • Zoology 425: Behavioral Ecology

Published Papers:

  • Allan, B. F., H. P. Dutra, L. S. Goessling, K. Barnett, J. M. Chase, R. J. Marquis, G. Pang, G. A. Storch, R. E. Thach, and J. L. Orrock. In press. Invasive honeysuckle eradication reduces tick-borne disease risk by altering host dynamics. Proceedings of the National Academy of Sciences USA
  • Conley, A. K., Watling, J. I., and J. L. Orrock. In press. Invasive plant alters ability to predict disease vector distribution. Ecological Applications
  • Watling, J. I., C. R. Hickman, and J. L. Orrock. In press. Predators and invasive plants affect performance of amphibian larvae. Oikos
  • Orrock, J. L., L. Dill, A. Sih, J. Grabowski, S. Peacor, B. Peckarsky, E. Preisser, and E. Werner. In press. Predator effects in predator-free space: the remote effects of predators on prey. The Open Ecology Journal
  • Watling, J. I., C. R. Hickman, E. Lee, K. Wang, and J. L. Orrock. In press. Lonicera maackii extracts increase mortality and alter behavior of some native amphibian larvae. Oecologia
  • Watling, J. I., A. J. Nowakowski, M. A. Donnelly, and J. L. Orrock. In press. Meta-analysis reveals the importance of matrix composition for animals in fragmented habitat. Global Ecology and Biogeography.
  • Haddad, N. M., B. Hudgens, E. I. Damschen, D. Levey, J. L. Orrock, J. Tewksbury, and A. Weldon. In press. Assessing both positive and negative effects of corridors. For: Perspectives from Source-Sink Dynamics.
  • Mulder, C. P. H., H. Jones, K. Kameda, C. Palmborg, S. Schmidt, J. Ellis, J. L. Orrock, A. Wait, D. A. Wardle, L. Yang, H. Young G, D. Croll, and E. Vidal. In presss. Impacts of seabirds on plant and soil properties. For: Seabird islands: Ecology, Invasions, and Restoration. C. P. H. Mulder, W. B. Anderson, D. R. Towns, and P. J. Bellingham, editors. Oxford University Press.
  • Orrock, J. L., M. L. Baskett, and R. D. Holt. 2010. Spatial interplay of plant competition and consumer foraging mediate plant coexistence and drive the invasion ratchet. Proceedings of the Royal Society B 277: 3307-3315.
  • Orrock, J. L. and J. I. Watling. 2010. Local community size mediates ecological drift and competition in metacommunities. Proceedings of the Royal Society B 277: 2185-2191.
  • Mattos, K. J., and J. L. Orrock. 2010. Behavioral consequences of plant invasion: an invasive plant alters rodent anti-predator behavior. Behavioral Ecology 21:556-561.
  • Sih, A., D. I. Bolnick, B. Luttbeg, J. L. Orrock, S. D. Peacor, L. M. Pintor, E. Preisser, J. S. Rehage, and J. R. Vonesh. 2010. Predator-prey naivete, antipredator behavior, and the ecology of predator invasions. Oikos 119:610-621.
  • Orrock, J. L. 2010. When the ghost of predation has passed: do rodents from islands with and without fox predators exhibit aversion to fox cues? Ethology 116:338-345.
  • Orrock, J. L. and C. C. Christopher. 2010. Density of intraspecific competitors determines the occurrence and benefits of accelerated germination. American Journal of Botany 97:694-699.
  • Orrock, J. L., R.D. Holt, and M. L. Baskett. 2010. Refuge-mediated apparent competition in plant-consumer interactions. Ecology Letters 13:11-20.
  • Orrock, J. L. and M. S. Witter. 2010. Multiple drivers of apparent competition reduce re-establishment of a native plant in invaded habitats. Oikos 119:101-108.
  • Watling, J. I. and J. L. Orrock. 2010. Measuring edge contrast using biotic criteria helps define edge effects on the density of an invasive plant. Landscape Ecology 25:69-78.
  • Motheral, S. M., and J. L. Orrock. 2010. Gastropod herbivore preference for seedlings of two native and two exotic grass species. American Midland Naturalist 163:106-114.
  • Heldermon, C. D., K. K. Ohlemiller, E. D. Herzog, C. Vogler, E. Y. Qin, D. F. Wozniak, Y. Tan, J. L. Orrock, and M. S. Sands. 2010. Therapeutic efficacy of bone marrow transplant, intracranial AAV-mediated gene therapy or both in the mouse model of MPS IIIB. Molecular Therapy 18:873-880.
  • Orrock, J. L. and B. J. Danielson. 2009. Temperature and cloud cover, but not predator urine, affect winter foraging of mice. Ethology 115:641-648.
  • Orrock, J. L. and J. L. Hoisington-López. 2009. Mortality of exotic and native seeds in invaded and uninvaded habitats. Acta Oecologica 35: 758-262.
  • Seabloom, E. W., E. T. Borer, B. A. Martin, and J. L. Orrock. 2009. Effects of long-term consumer manipulations on invasion in oak savannah communities. Ecology 90: 1356-1365.
  • Vellend, M. and J. L. Orrock. 2009. Ecological and genetic models of diversity: Lessons across disciplines. Pages 439-461 in: The Theory of Island Biogeography Revisited. J. Losos and R. E. Ricklefs, editors. Princeton University Press.
  • Orrock, J. L., M. S. Witter, and O. J. Reichman. 2009. Native consumers and seed limitation constrain the restoration of a native perennial grass in exotic habitats. Restoration Ecology 17: 148-157.
  • Damschen, E. I., L. A. Brudvig*, N. M. Haddad, D. J. Levey, J. L. Orrock, and J. J. Tewksbury. 2008. The movement ecology and dynamics of plant communities in fragmented landscapes. Proceedings of the National Academy of Sciences USA 105: 19078-19083.
  • Orrock, J. L., J. H. Grabowski, S. D. Peacor, B. L. Peckarsky, E. L. Preisser, A. Sih, and E. E. Werner. 2008. Consumptive and non-consumptive effects of predators on metacommunities of competing prey. Ecology 89: 2426-2435.
  • Peckarsky, B. L., D. I. Bolnick, L. M. Dill, J. H. Grabowski, B. Luttbeg, J. L. Orrock, S. D. Peacor, E. L. Preisser, O. J. Schmitz, and G. C. Trussell. 2008. Revisiting the classics: Considering non-consumptive effects in textbook examples of predator-prey interactions. Ecology 89: 2416-2425.
  • Orrock, J. L., M. S. Witter, and O. J. Reichman. 2008. Apparent competition with an exotic plant reduces native plant establishment. Ecology 89: 1168-1174.
  • Orrock, J. L. and B. A. Allan. 2008. Sin Nombre virus infection in deer mice, Channel Islands, California. Emerging Infectious Diseases 14: 1965-1966.
  • Preisser, E. L., J. L. Orrock, and O. J. Schmitz. 2007. Predator hunting mode and habitat domain affect the strength of non-consumptive effects in predator-prey interactions. Ecology 88: 2744-2751.
  • Orrock, J. L. and E. I. Damschen. 2007. The effect of burial depth on removal of seeds of Phytolacca americana. Southeastern Naturalist 6: 151-158.
  • Orrock, J. L. 2006. Useful distraction: Ritualized behavior as an opportunity for recalibration. Behavioral and Brain Sciences 29: 625-626.
  • Orrock, J. L., D. J. Levey, B. J. Danielson, and E. I. Damschen. 2006. Seed predation, not seed dispersal, explains the landscape-level abundance of an early-successional plant. Journal of Ecology 94: 838-845.
  • Damschen, E. I., N. M. Haddad, J. L. Orrock, D. J. Levey, and J. J. Tewksbury. 2006. Corridors increase plant species richness at large scales. Science 313: 1284-1286.
  • Orrock, J. L. and R. J. Fletcher, Jr. 2005. Changes in community size affect the outcome of competition. American Naturalist 166: 107-111.
  • Orrock, J. L. 2005. Conservation corridors affect the fixation of novel alleles. Conservation Genetics 6: 623-630.
  • Orrock, J. L. and E. I. Damschen. 2005. Corridors cause differential seed predation. Ecological Applications 15: 793-798.
  • Orrock, J. L. and B. J. Danielson. 2005. Patch shape, connectivity, and foraging by the oldfield mouse, Peromyscus polionotus. Journal of Mammalogy 86: 569-575.
  • Orrock, J. L. 2005. The effect of gut passage by two species of avian frugivores on seeds of Pokeweed, Phytolacca americana. Canadian Journal of Botany 83: 427-431.
  • Orrock, J. L. and E. I. Damschen. 2005. Fungi-mediated mortality of seeds of two oldfield plant species. Journal of the Torrey Botanical Society 132: 613-617.
  • Orrock, J. L. and B. J. Danielson. 2005. A note on the status of the endangered red-backed vole, Clethrionomys gapperi, in Iowa. Journal of the Iowa Academy of Science 112: 24-25.
  • Brinkerhoff, R. J., N. M. Haddad, and J. L. Orrock. 2005. Corridors and olfactory predator cues affect small mammal behavior. Journal of Mammalogy 86: 662-669.
  • Orrock, J. L. and B. J. Danielson. 2004. Rodents balancing a variety of risks: invasive fire ants and indirect and direct indicators of predation risk. Oecologia 140: 662-667.
  • Orrock, J. L., B. J. Danielson, and J. Brinkerhoff. 2004. Rodent foraging is affected by indirect, but not by direct, cues of predation risk. Behavioral Ecology 15: 433-437.
  • Orrock, J. L., B. J. Danielson, M. J. Burns, and D. J. Levey. 2003. Spatial ecology of predator-prey interactions: corridors and patch shape influence seed predation. Ecology 84: 2589-2599.
  • Orrock, J. L., D. Farley, and J. F. Pagels. 2003. Does fungus consumption by the woodland jumping mouse vary with habitat or the abundance of other small mammals? Canadian Journal of Zoology 81: 753-756.
  • McShea, W. J., J. F. Pagels, J. L. Orrock, E. Harper, and K. Koy. 2003. Mesic deciduous forest as patches of small mammal richness within an Appalachian mountain forest. Journal of Mammalogy 84: 627-643.
  • Orrock, J. L. and J. F. Pagels. 2003. Tree communities, microhabitat characteristics, and small mammals associated with the endangered rock vole, Microtus chrotorrhinus, in Virginia. Southeastern Naturalist 2: 547-558.
  • Tewksbury, J. J., D. J. Levey, N. M. Haddad, S. Sargent, J. L. Orrock, A. Weldon, B. J. Danielson, J. Brinkerhoff, E. I. Damschen, and P. Townsend. 2002. Corridors affect plants, animals, and their interactions in fragmented landscapes. Proceedings of the National Academy of Sciences USA 99: 12923-12926.
  • Orrock, J. L. and J.F. Pagels. 2002. Fungus consumption by the southern red-backed vole, Clethrionomys gapperi, in the southern Appalachians. American Midland Naturalist 147: 413-418.
  • Orrock, J. L., J.F. Pagels, W.J. McShea, and E.K. Harper. 2000. Predicting presence and abundance of a small mammal species: the effect of scale and resolution. Ecological Applications 10: 1356-1366.
  • Orrock, J. L., E.K. Harper, J.F. Pagels, and W.J. McShea. 1999. Additional records of the rock vole, Microtus chrotorrhinus (Mammalia: Muridae), in Virginia. Banisteria: Journal of the Virginia Natural History Society 14: 36-38.
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