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Ingrid M. Parker Department of Ecology and Evolutionary Biology University of California at Santa Cruz Santa Cruz, CA 95064 (831) 459-5017 email: parker@biology.ucsc.edu Birth Announcement: Elias Balslev Gilbert |
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Ingrid M. Parker Department of Ecology and Evolutionary Biology University of California at Santa Cruz Santa Cruz, CA 95064 (831) 459-5017 email: parker@biology.ucsc.edu Birth Announcement: Elias Balslev Gilbert |
| RATES OF SPREAD
IN THE NOXIOUS INVASIVE SHRUB, SCOTCH BROOM Invasions are driven by a combination of dispersal and population growth. I use age-structured models and spatial models to investigate the relative importance of factors that influence spread in invasive species. In Washington State, I found that reproduction in Scotch broom is strongly limited by pollinators (see Parker 1997). It also has eliasomes and is ant-dispersed; however, spatial models showed that the additional movement by ants is not very important relative to demographic factors (Parker and Reichard 1998). Interestingly, the sites where broom was most successful were the glacial outwash prairies, an ecosystem rich in native species that has been nearly eliminated by agriculture and development (Parker 2000). I continue to pursue my interest in using models to understand the relative importance of different ecological factors or processes to spatial spread. As part of a working group run by Mike Neubert and Hal Caswell at NCEAS, we are applying stage-structured, analytical spatial models to link dispersal and demography in invading species. |
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HOW DOES SCOTCH
BROOM AFFECT SPECIES COMPOSITION AND NITROGEN CONTENT IN
THE GLACIAL OUTWASH PRAIRIES? In Washington, Scotch broom is a big, nitrogen-fixing shrub that invades grassland ecosystems that include no large native shrubs. Two undergraduates and I documented a change in plant diversity and species composition when Scotch broom invades prairie sites and old field sites (Parker et al. 1998). During my time as a postdoc in Carla DAntonio's lab at UC Berkeley, I teamed up with Karen Haubensak, the N-Fixation Queen, to investigate whether these changes in composition were accompanied by changes in nutrient levels in the soil. We found a significant increase in total nitrogen, total carbon, and net nitrogen mineralization. |
| COMPARATIVE
REPRODUCTIVE ECOLOGY OF SCOTCH AND FRENCH BROOM IN
CALIFORNIA When I moved to California, I was curious to see whether pollinator limitation of Scotch broom is a general phenomenon, or specific to the cold, rainy conditions of the Pacific Northwest. Karen Haubensak and I have been studying the reproductive success of Scotch broom and French broom in Marin County (Mt. Tamalpais State Park). These two exotic species are very similar, but French broom flowers are about 10 times smaller. Scotch broom is more attractive to pollinators, but we found that both species were pollen limited. |
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TESTING THE
"NATURAL ENEMIES HYPOTHESIS" WITH CLOVERS It is often stated that exotic species leave their natural enemies behind in their home range, and are therefore released from pest pressure and free to wreak havoc on native species. Plant pathologist and microbial ecologist Greg Gilbert and I are investigating the generality of this idea using clovers at the UC Natural Reserve at Bodega Bay. There we find 10 native and 8 exotic species of clovers living sympatrically, and we are studying effects of pathogens and herbivores on the fitness of individuals from all 18 species. We find strong evidence that herbivores do prefer native species. |
| THE EVOLUTION OF
NOVEL PLANT-PATHOGEN INTERACTIONS Is a potential invader more likely to "escape" pathogens, or conversely to be clobbered by new pathogens to which it has no resistance? In experiments conducted in environmental chambers, Greg Gilbert and I are comparing the pathogenicity and evolution of virulence of California pathogens on native clovers, exotic clovers collected from California, those same species collected from their native range, and clovers that have never been grown in California. Many of the species are native to the Mediterranean, requiring two tedious field trips to France and Spain. |
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GENETIC
DIFFERENTIATION IN THE INVADER, COMMON MULLEIN In California, Common mullein (Verbascum thapsus) is now found from sea level up to 7000+ feet in the Sierra Nevada. There are reports from resource managers at Yosemite National Park that it may be increasing its range upward. Does this broad geographic and environmental range reflect huge levels of phenotypic plasticity, or is there evidence for local adaptation in high elevation populations? Do reports of the increasing range of mullein simply reflect range expansion of existing genotypes, or adaptation, or possibly global warming? Stay tuned. See also Joseph's page. |
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PORROCA: THE
SPREAD OF A NEW COCONUT DISEASE IN KUNA YALA, PANAMA. The discovery and study of a novel crop disease has an obvious practical importance. It also represents an opportunity to study the dynamics of an invasion, and the relationship between spread and the distribution of the host. Porroca is a disease of coconut palms for which the causative agent is still unknown. In recent years, porroca has entered an epidemic phase of rapid spread along the Caribbean coast, from Colombia through Panama. With the help of the Kuna People of San Blas (Kuna Yala), Greg Gilbert and I are studying the biology of porroca: determining the cause, the vector, and the basic epidemiology, and investigating possible control options with landscape-scale, community-based controlled experiments. A main focus of our work is a set of detailed GPS/GIS maps of healthy and sick palms to follow and eventually model the dynamics of spread along linear plantations and patchy island systems. |
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IMPACTS OF
INVASIVE SPECIES: TOWARD A THEORETICAL FRAMEWORK Although ecologists commonly refer to the impacts of nonindigenous species, little formal attention has been given to defining what we mean by impact, or connecting ecological theory with particular impact measures. The resulting lack of generalizations regarding invasion impacts is more than an academic problem; we need to be able to distinguish invaders with minor effects from those with large effects in order to prioritize management efforts. Our working group at the National Center for Ecological Analysis and Synthesis (NCEAS) focused on defining, evaluating, and comparing the ways people measure impact (Parker et al. 1999). Are the results of complex multivariate methods adequately captured by simple composite metrics such as species richness? How well are impacts on native populations correlated with impacts on ecosystem functions, and which drive which? Are there useful bioindicators for invasion impacts? To what extent does the impact of an invasive species depend on the system in which it is measured? Three approaches would provide new insights in this line of inquiry: 1) studies that measure impacts at multiple scales and multiple levels of organization, 2) studies that synthesize currently available data on different response variables, and 3) models designed to guide empirical work and explore generalities. |
Beckstead, J. and I.M. Parker. Invasiveness of Ammophila arenaria: release from soil-borne pathogens? Ecology, in review.
Neubert, M.G. and I.M. Parker. Using integrodifference equations to project rates of spread for invasive species. Risk Analysis, in review.
Haubensak, K.A. and I.M. Parker. Invasion of Cytisus scoparius in glacial outwash prairies of western Washington: Determining impacts on ecosystems. Plant Ecology, in review.
Parker, I.M., J. Rodriguez, and M.E. Loik. 2003. An evolutionary approach to understanding the biology of invasions: local adaptation and general purpose genotype in the weed Verbascum thapsus. Conservation Biology, in press.
Parker, I.M. 2002. Safe site and seed limitation in Cytisus scoparius: Invasibility, disturbance, and the role of cryptogams in a glacial outwash prairie. Biological Invasions 3(4): 323-332.
Parker, I.M., Engel, A., Haubensak, K.A., and Goodell, K. 2002. Pollination of Cytisus scoparius and Genista monspessulana, two invasive shrubs in California. Madroño 49:25-32.
Byers, J.E., Reichard, S., Smith, C.S., Parker, I.M., Randall, J.M., Lonsdale, W.M., Atkinson, I.A.E., Seasted, T., Chornesky, E., Hayes, D., Williamson, M. 2002. Directing research to reduce the impacts of non-indigenous species. Conservation Biology 16(3):630-640.
Parker, I.M. and Haubensak, K.A. 2002. Comparative pollinator limitation of two non-native shrubs: Do mutualisms influence invasions? Oecologia 130:250-258.
Hayden K.A. and Parker, I.M. 2002. Plasticity in cyanogenesis of Trifolium repens L: Inducibility, fitness costs and variable expression. Evolutionary Ecology Research 4:155-168.
Sakai, A.K., Weller, S.G., Allendorf, F.W., Holt, J.S., Lodge, D.M., Molofsky, J., With, K.A., Baughman, S., Cabin, R.J., Cohen, J.E., Ellstrand, N.C., McCauley, D.E., O'Neil, P., Parker, I.M., and Thompson, J.N. 2001. The Population Biology of Invasive Species. Annual Review of Ecology and Systematics. 32:30532.
Parker, I.M. 2000. Invasion dynamics of Cytisus scoparius: A matrix model approach. Ecological Applications10(3):726-743.
Goodell, K., I.M. Parker, and G.S. Gilbert. 2000. Biological impacts of species invasions: Implications for policy makers. pp. 87-117, in National Research Council of the United States, ed, Incorporating Science, Economics, and Sociology in Developing Sanitary and Phytosanitary Standards in International Trade (Washington: National Academy of Sciences Press).
Parker, I.M., D. Simberloff, W.M. Lonsdale, K. Goodell, M. Wonham, P.M. Kareiva, M.H. Williamson, B. Von Holle, P.B. Moyle, J.E. Byers, and L. Goldwasser. 1999. Impact: Toward a framework for understanding the ecological effects of invaders. Biological Invasions 1(1):3-19.
Parker, I.M. and S.H. Reichard. 1998. Critical issues in invasion biology for conservation science. pp.283-305, in P.L. Fiedler and P.M. Kareiva, eds., Conservation Biology (Chapman Hall).
Parker, I.M. 1997. Pollinator limitation of Cytisus scoparius, an invasive exotic shrub. Ecology 78:1457-70.
Parker, I.M., W.S. Harpole, and D. Dionne. 1997. Plant community diversity and invasion of the exotic shrub Cytisus scoparius: Testing hypotheses of invasibility and impact. pp. 149-162, in P.V. Dunn, and K. Ewing, eds., Ecology and conservation of the South Puget Sound prairie landscape (Seattle: The Nature Conservancy Press).
Parker, I.M., and Bartsch, D. 1996. Recent advances in ecological biosafety research on the risks of transgenic plants: a trans-continental perspective. pp. 147-161, in J. Tomiuk, K. Wöhrmann, and A. Sentker, eds., Transgenic Organisms: Biological and Social Implications (Basel: Birkhœuser Verlag), .
Kareiva, P., Parker, I.M., and Pascual, M. 1996. How useful are experiments and models in predicting the invasiveness of genetically engineered organisms? Ecology 77(6):1670-1675.
Parker, I.M., and Kareiva, P. 1996. Assessing the risks of genetically engineered organisms: acceptable evidence and reasonable doubt. Biological Conservation 78:193-203.
Ruesink, J.L., Parker, I.M., Groom, M.J., and Kareiva, P. 1995. Guilty until proven innocent: Reducing the risks of non-indigenous species introductions. Bioscience 45(7):465-477.
Parker, I.M., Nakamura, R., and Schemske, D.W. 1995. Inbreeding depression in two sympatric species of Epilobium (Onagraceae) with contrasting mating systems. The American Journal of Botany 82(8):1007-1016.
Parker, I.M. and P. Kareiva. 1994. Assessing the risk of invasion in genetically modified crops: An ecological perspective. pp. 467-470, in D.D. Jones, ed., The Biosafety Results of Field Tests of Genetically Modified Plants and Microorganisms (University of California Division of Agriculture and Natural Resources).
Schemske, D.W., Husband, B.C., Ruckelshaus, M.H., Goodwillie, C., Parker, I.M., and Bishop, J. 1994. Evaluating approaches to the conservation of rare and endangered plants. Ecology 75(3):584-606.
Parker, I.M., Mertens, S.K., and Schemske, D.W. 1993. Distribution of seven native and two exotic plants in a tallgrass prairie in southeastern Wisconsin: the importance of human disturbance. The American Midland Naturalist 130(1):43-55.
Parker, I.M. 2001. Invasion ecology: echoes of Elton in the 21st century. Review of C.S. Elton, The Ecology of Invasions by Animals and Plants, and J. Van Driesche and R. Van Driesche, Nature out of Place: Biological Invasions in the Global Age. Conservation Biology.
Parker, I.M. 2000. Invasion Ecology. McGraw-Hill Encyclopedia of Science and Technology, 9th Edition.
Parker, I.M. 1997. Review of P. Pysek, M. Rejmanek, and M. Wade, eds., Plant Invasions: General Aspects and Special Problems. The Quarterly Review of Biology 72(2):208.
Kareiva, P., and Parker, I.M. 1995. Developing a case study method for conservation biology. Ecology 76(3): 1023-1024.