Brigitte Tenhumberg Assistant Professor PhD University of Göttingen, Germany 1992   205A Manter Hall 402.472.0267 btenhumberg2@unl.edu
My research interests comprise invasion ecology and optimal decisions in insect behavior and life history. I use mathematical models tailored to specific biological systems to increase our understanding of ecological processes.In particular, I am interested in linking theoretical and empirical work, constructing models that make testable predictions, and if necessary use empirical tests to modify the model.

Invasion Ecology Biological invasions represent a major threat to natural and agricultural ecosystems worldwide. My research emphasis is concerned with understanding 1) the underlying mechanism(s) causing a non-invasive species to become invasive in an alien environment, and 2) the role of natural enemies in ecosystem resistance to invasions.

1) Signal of invasion potential: At the forefront of an invasion there are typically only a small number of alien individuals dominated by dispersal states (e.g. seeds), which have a high risk of extinction because of demographic stochasticity and Allee effects (reduced fitness when conspecific density is low). In addition, the feeding activity of predators reduces low numbers even further, and alien organisms are usually mal­adapted to their new environment. We have little information on failed establishments, but the low success rate in establishing biocontrol agents demonstrates how problematic this phase really is. I am interested in life history traits or combination of traits facilitating this sensitive early phase of an invasion. 2) Natural enemy hypothesis: There is a lot of evidence that native herbivores include exotic species in their food range potentially affecting plant vital rates such as survival, seed production. I am interested in quantifying the population consequences of natural enemies and searching for additional control factor working in concert with natural enemies.

Optimal Decisions

Insects have to decide how best to exploit the resources in their environment (food, hosts, mates), and how best to allocate these resources (reproduction, growth, energy storage). There is increasing evidence that individual behavior has a genetic component, thus it is fair to assume that natural selection will favor individuals that behave as to optimize their fitness, and such a behavior can be predicted using optimization models. In particular, I am interested in behavioral decisions that depend on internal or external states. For example, it makes sense that newly emerged parasitoids will use less risky foraging strategies compared to individuals close to the end of their life expectancy.

Recent Publications

• Tyre, A.J., Tenhumberg, B. and Bull, C.M. (2006): Identyfying landscape pattern from individual scale processes. Ecological Modelling, in press
• Tenhumberg, B., Siekman, G, and Keller, M.A. (2006): Optimal time allocation in parasitic wasps searching for hosts and food. Oikos 113: 121-131.
• Siekmann, G., Keller, M.A., and Tenhumberg, B. (2004): The sweet tooth of adult parasitoid Cotesia rubecula: ingnoring hosts for nectar? Journal of Insect Behavior 17 (4): 459-476.
• Tenhumberg, B., Tyre, A.J. Shea, K. and Possingham, H.P. (2004): Linking wild and captive populations to maximize species persistence: optimal translocation strategies. Conservation Biology 18 (5): 1304-1314.
• Tenhumberg, B., Tyre, A.J., Pople, and A. Possingham, H.P. (2004): Do harvest refuges buffer kangaroos against evolutionary responses to selective harvesting. Ecology 85 (7): 2003-2007.
• Tyre, A.J., Tenhumberg, B., Field, S.A., Niejalke, D., Parris, K., Possingham, H.P. (2003): Improving precision and reducing bias in biological surveys by estimating false negative error rates in presence-absence data. Ecological Applications 13 (6): 1790-1801.
• Tyre, A.J., Bull, C.M., Tenhumberg, B., and Chilton, N. (2003): Indirect evidence of density-dependent population regulation in Aponomma hydrosauri (Acari: Ixodidae), an ectoparasite of reptiles. Australian Journal of Ecology 28, 196-203.
• Tenhumberg, B., Keller, M.A., Possingham, H.P., and Tyre, A.J. (2001): The effect of resource aggregation at different scales: optimal foraging behaviour of Cotesia rubecula, The American Naturalist 158 (5), 505-518.
• Siekmann, G., Tenhumberg, B. and Keller, M.A. (2001): Feeding and Survival in Parasitic Wasps: Sugar concentration and Timing matters, Oikos 95 (3), 425-430.
• Tenhumberg, B., Keller, M.A., Possingham, H.P., and Tyre, A.J. (2001): Optimal patch leaving behaviour: a case study using the parasitoid Cotesia rubecula, Journal of Animal Ecology 70, 683-691.
• Tenhumberg, B., Keller, M.A., and Possingham, H.P. (2001): Using Cox’s proportional hazard models to implement optimal strategies: en example from behavioural ecology, Mathematical and Computer Modelling 33, 597-607.
• Tyre, A.J., Tenhumberg, B., McCarthy, M.A., and Possingham, H.P. (2000): Swapping space for time and unfair tests of ecological models. Australian Journal of Ecology 25, 327-331.
• Tyre, A.J., and Tenhumberg, B. (2000): Hidden mechanisms generate negative feedbacks in a stochastic model. Australian Journal of Ecology 25, 305-307.
• Tenhumberg, B., Tyre, A.J., and Roitberg, B.D. (2000): Stochastic variation in food availability influences weight and age at maturity. Journal of Theoretical Biology 202, 257-272.

This page was last updated on April 10, 2006.