Biotic Stress and Yield Loss

associated habitats that are predicted to alter the impact of herbivory in both negativeand positive directions. In addition, given the strong changes in genotype by environmentinteractions selected for both within and between species comparisons, thenthe potential for changes in plant phenotype due to domestication also alters the predictedresponses.Appropriate uses of pooled data might include looking for types of responsesto herbivory in a qualitative sense or looking for potentially novel changes. Finally,the variation in phenotypes generated by artificial selection also allows for examinationof specific plant traits that may have minimal variation for other traits (e.g., contrastsof cultivars with different allocation patterns or contrasts of determinate andindeterminate phenotypes). Similarly, environmental conditions can be modifiedwith precision while maintaining uniformity of other factors such as soil type, waterstress levels, and topography. Therefore, the pooling of literature remains a richresource for developing and addressing particular questions while also potentiallygenerating erroneous patterns by inclusion of the systematic biases across literaturebases.Within agricultural studies, correlates among general vigor, inter- and intraspecificcompensatory growth, compensatory gas exchange responses, mechanicalstrength of various plant tissues, differential allocation patterns, and plant tolerancehave been observed. 175 Whereas many crop breeding programs have successfullyenhanced or incorporated resistant traits into modern cultivars, 55–57 it has been suggestedthat incorporation of many traits is hindered by difficulties of separating positiveresistant traits from associated negative agronomic traits. 176REFERENCES1. Kogan, M., Plant defense strategies and host-plant resistance, in Ecological Theory andIntegrated Pest Management, Kogan, M., Ed., John Wiley & Sons, New York, 1986, 83.2. Fritz, R. S., and Simms, E. L., Ecological genetics of plant-phytophage interactions, inPlant Resistance to Herbivores and Pathogens: Ecology, Evolution and Genetics, Fritz,R. S., and Simms, E. L., Eds., University of Chicago Press, Chicago, 1992, 1.3. Herms, D. A., and Mattson, W. J., The dilemma of plants: to grow or defend, Q. Rev.Biol., 67, 283, 1992.4. Trumble, J. T., Kolodny-Hirsch, D. M., and Ting, I. P., Plant compensation for arthropodherbivory, in Annual Review of Entomology, Mittler, T. E., Radovsky, F. J., and Resh, V.H., Eds., Annual Reviews, Palo Alto, CA, 1993, 93.5. Welter, S. C., Arthropod impact on plant gas exchange, in Plant-insect Interactions,Bernays, E. A., Ed., CRC Press, Boca Raton, 1989, 135.6. Baldwin, I. T., and Preston, C. A., The eco-physiological complexity of plant responsesto insect herbivores Planta, 208, 137, 1999.7. Stowe, K. A., Marquis, R. J., Hochwender, C. G., and Simms, E. L., The evolutionaryecology of tolerance to consumer damage Annu. Rev. Ecol. Syst., 75, in press.8. Strauss, S. Y., Levels of herbivory and parasitism in host hybrid zones Trends Ecol. Evol.,9, 209, 1994.9. Strauss, S. Y., Siemes, D. H., Decher, M. B., and Mitchell-Olds, T., Ecological costs ofplant resistance to herbivores in the currency of pollination Evolution, 53, 1105, 1999.