Evolutionary Ecology in Ecosystems

Research in this area focuses on examining the selective pressures imposed by the physical and biological environments and evolutionary response to these pressures. This discipline recognizes that distributions of species trait are rapidly changing in response to interspecific or intraspecific interactions, both during ontogeny (i.e., phenotypic plasticity)and between generations. Detailed examination of rates of phenotypic changes, their adaptive benefits and consequent costs may reveal variation in the strength of species interactions, either directly or indirectly through changes in population dynamics. We use this endeavor as a foundation for better understanding of community dynamics and ecosystem functions as a whole.

Click here to view a video showing one possible way to measure phenotypic variation in grasshoppers-jumping mechanics.

Specific research projects in this area include:

Predator functional trait-hunting mode-and ecosystem function-Oswald Schmitz

Predator indirect effects on plant community composition (dashed lines) and on ecosystem functions (dotted lines). (A) Predators can influence ecosystem function via the direct causal chain (depicted by solid arrows) running from predators through herbivores through plant community composition. Plant community composition in turn regulates NPP: the quality and quantity of plant matter entering the soil organic matter pool to be decomposed and produce N mineralization. In the study ecosystem, predator indirect effects on plant community composition depended on how predators affect their grasshopper herbivore M. femurrubrum prey. (B) The actively hunting spider P. rimator causes density reductions of the grasshopper, which leads to indirect positive effects on grass and S. rugosa and an indirect negative effect on other herbs because the competitive dominant plant S. rugosa suppresses other herbs. (C) The sit-and-wait spider P. mira causes grasshopper foraging shifts from preferred nutritious grass to safer S. rugosa. This predator has indirect positive effects on grasses and other herbs and an indirect negative effect on S. rugosa. These hunting mode-dependent differences in plant composition have different effects on ecosystem properties like production, mineralization, and C:N ratio of decomposing plant litter. (Schmitz 2008, Science)

Predation risk, herbivore physiology and ecosystem nutrient balance. This area of research explores how changes in herbivore physiological demand for C and N in response to predation risk can lead to shifts in C:N content of organic material along 4 pathways that eventually lead to the organic matter pool to be decomposed: (A) C:N composition of herbivore body tissue; (B) C:N composition of herbivore feces; (C) changes in C:N content of Solidago tissue damaged by herbivory; and (D) changes in C:N content of the herb community owing to mediation of Solidago competitive dominance by herbivory in the face of predation risk. Solid magenta arrows indicate direct trophic interactions; dashed magenta arrows indicate a non-trophic fear effect. Arrow thickness indicates food preference under risk conditions. Green arrows indicate the source and fate of tissue C and N in the ecosystem-Dror Hawlena and Oswald Schmitz