Kevin Rice

Professor in Plant Sciences





Research Interests

My basic research efforts focus on 1) the use of ecological genetics to address questions about patterns of plant evolution and mechanisms of adaptation and 2) the ecology and physiology of plant competition and stress tolerance.  These research topics contribute to problem solving in areas that I think are currently very important areas of applied ecology: conservation biology, restoration ecology and invasion biology.

Kevin Rice CV [pdf] 

The Ecology and Evolution of Biological Invasions – Our lab has developed a substantial research program on the population ecology and ecological genetics of invasions within a diverse number of ecosystems. Much of the ecological work in the lab has focused on understanding how temporal and spatial heterogeneity fosters the establishment of invasive species and influences the impact of invasives on native species and communities. A good example of the importance of heterogeneity in the invasion process at the community level is some work Davies et al 2005 Ecology.pdf that addressed the long standing debate regarding the importance of scale in the correlation between native and exotic diversity.  At the species level, two studies with a former student (Dr. Kim Reever-Morghan) on the competitive interactions between the noxious range weed yellow starthistle (Centaurea solstitialis) and the native perennial bunchgrass purple needlegrass (Nassella pulchra) also illustrate how temporal and spatial variability in resources can influence the competitive interactions between invasive and native species Reever-Morghan and Rice Rest Ecol 2005.pdf  Reever-Morghan and Rice Eco Apps 2006.pdf

The importance of evolutionary changes in promoting invasiveness of a species is just starting to be recognized in invasion biology; a field that has been dominated by a species approach that often discounts the importance of intraspecific variation and the potential for rapid evolutionary change within invasive species. Work with former student Dr. Beth Leger on California poppy as an invader in Chile indicated that both plasticity Leger and Rice 2003 Eco Letters.pdf and genetic differentiation Leger and Rice 2007 J Evo Bio.pdf were important evolutionary responses allowing poppy to spread within Chile. As part of ongoing studies on the potential for rapid evolutionary change in exotic species, we have started to publish results from our current study on microevolutionary change along invasion fronts of California’s newest noxious weed, barbed goatgrass (Aegilops triuncialis).  This project is using both field studies and molecular markers to understand the importance of genetic differentiation and phenotypic plasticity in promoting the rapid expansion of this weed throughout California’s rangelands.  Using microsatellite markers, we have demonstrated a severe genetic bottleneck in this species that suggests that genetic variability for adaptive differentiation in this species does not come from repeated introductions Meimberg et al Bio Invasions 2006.pdf.  Instead we suggest that novel sources of genetic variation, such as quantitative trait mutation or epigenetic effects, may be important for adaptive radiation in this and other strongly bottlenecked invasives. 

Ecology, Ecophysiology, and Ecological Genetics of Native Rangeland Species - Drought and annual variation in rainfall are major factors influencing grassland or woodland  productivity and the population dynamics of many component species.  A well-known example of a major impact of drought on savanna productivity and structure is the “die-back” that occurs in Australian eucalyptus woodlands in response to severe periodic drought (e.g., the “100 year” drought).  Using field measurements of water stress and laboratory measurements of hydraulic conductivity, we were able to explain both among species and within species differences in susceptibility to die-back Rice et al 2004 Oecologia.pdf. Rooting depth was a major determinant of differences among species while resistance to cavitation was an important mechanism that explained differences in die-back rates between adults and saplings within species.  Year-to-year variation in climate was also an important factor determining the survival and reproductive success of restored populations of California purple needlegrass Marty et al Plant Ecol 2005.pdf; although management treatments of grazing and fire had effects on needlegrass demography, annual variation in rainfall had an often overwhelming effect on population growth, and thus, restoration success.

            A final major area of my research is on the relative roles of gene flow and selection in structuring patterns of adaptation in native plant species.  In addition to the intrinsic value in understanding processes in plant microevolution, there has also heightened interest on the part of restoration practitioners on scales and patterns of local adaptation and how patterns of adaptation affect the success of ecological restoration McKay et al Rest ecol 2005.pdf.  A series of field experiments with former student Dr. Julianno Sambatti on the serpentine endemic sunflower (Helianthus exilis) indicated pronounced local adaptation to edaphic gradients in this species.  By combining these field experiments with molecular markers, we determined that adaptation occurred despite very high levels of gene flow suggesting, in turn, very strong selection pressures Sambatti and Rice 2006 Evolution.pdf.  Despite the widespread recognition of the potential importance of competition in plant evolution, there is essentially no information on the effect of competition on the expression of local adaptation.  Our studies with sunflower and another study with former post-doc Dr. Eric Knapp on two species of native grasses indicate that the expression of local adaptation can be much more pronounced under competition Rice and Knapp Rest. Ecol 2007.pdf.  This supports the idea that biotic selection may be a potent force in local adaptation and has practical implications for the restoration of native plant species.