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Faculty Image John Maron
Phone: (406) 243-6202
Website: Click Here


Current Position:

Associate Professor


I am a professor in DBS with interests in population and community ecology.

Office Hours:

Tuesday, Thursday 12:30-1:30

Field Of Study:

Plant population and community ecology

Research Interests:

In a general sense, I am interested in how species interactions influence plant distribution and abundance. Much of my research has involved large-scale field experiments to address how particular interactions influence the demography and population abundance of component species in a community. Below is a brief description of some of the research I have conducted.

Invasion Biology

Exotic species are transported to new regions where the abiotic and biotic environment may be quite different from their native range. We are interested in how successful exotics adapt to these new ecological circumstances. In particular, we seek to understand the importance of rapid genetically-based evolutionary change in enabling exotics to persist in newly colonized areas.

To examine these issues, I have studied St. John's Wort, Hypericum perforatum, a perennial plant native to Europe, North Africa and Asia that has been introduced into my continents around the world.  Classic ecological theory has long predicted that native plant diversity plays a key role in promoting resistance to exotic invasion. A central reason this may be so is that diverse native assemblages usually contain species that vary in how they capture resources. That is, diverse assemblages contain mixes of species that vary in their rooting depth, phenology, photosynthetic rates, and other functional attributes.

This increased functional diversity may enable diverse assemblages of plants to more efficiently capture resources than less diverse assemblages, thereby leaving less "free" resources available to colonizing exotics. Since resource availability may critically influence invasibility, one would predict that resource addition could influence the relationship between native diversity and invasibility. In collaboration with Marilyn Marler (link), we are exploring: 1) how resource availability interacts with native diversity to influence invasibility; 2) whether functional overlap between exotic and native plants influences invasibility; and 3) how native diversity, functional overlap between natives and exotics, and resource availability influence the impact that an invader has on a recipient community. We have initiated a large manipulative experiment where we are addressing these issues.

Food Web Ecology

At the simplest level, food webs describe who eats who in a community. However, beyond this description, food webs can summarize the important ecological interactions that influence the population growth and abundance of species in a community. I am interested in how top predators, through their effects on consumers, influence plant distribution and abundance. Across the Aleutian Islands in Alaska, we have studied how introduced predators and spatial subsidies influence plant community composition and productivity on islands across the archipelago.

In collaboration with Dr. Dean Pearson, I am conducting a large manipulative experiment to determine how mid-sized mammalian carnivores (weasel, fox, coyote, badger, mountain lion, etc.) and raptors, as a group, influence herbivorous and granivorous small mammal populations, and how small mammals, in-turn affect grassland productivity and diversity. Our goal is to test whether top predators have strong indirect cascading effects on terrestrial plant communities through their impacts on consumers.

We know from a growing number of studies that both invertebrate and vertebrate consumers can have strong impacts on plant performance and even plant fitness. Yet, quite surprisingly, we still have a very rudimentary understanding of when and where pervasive negative effects of consumers on plants actually translate to changes in plant abundance or distribution. That is, at the most fundamental level, we do not really know how commonly consumers limit plant abundance, alter plant population dynamics, or change plant distributions. As a result, predicting the conditions under which consumers have important population-level impacts on plants has proved difficult. I am interested in how variation in plant life history and environmental context interact to influence the population-level impacts of consumers on plants. 


Fall 08-BIOL448


Ph.D. 1996, Ecology Graduate Group, University of California, Davis.
M.S. 1983, Department of Biology, University of North Dakota.
B.S. 1980, Renewable Resources, University of California, Davis.

Teaching Experience:

  • Rocky Mountain Flora. University of Montana (Spring 2005).
  • Graduate course on plant-consumer interactions. University of Montana (Spring 2004).
  • Introductory Biology. University of Montana (Spring 2003- one of four instructors).
  • Terrestrial Plant Ecology. University of Montana (Fall 2002-2004).
  • Trends in Plant Ecology. University of Montana (Fall 2003-graduate seminar course, co-taught with R. Callaway).
  • Graduate "core" course in Ecology. University of Washington (Fall 2001-one of four instructors).
  • General Ecology. University of Washington (Winter 2001- one of three instructors).
  • Graduate course- Plant-Consumer Interactions. University of Washington (Winter 1999).
  • Introduction to Plant Ecology. University of Washington (Fall 1998-2001).
  • Sub-Tropical Field Ecology and Conservation. Universidad de Cordoba, Cordoba, Argentina (Spring, 1992).
  • Marine and Coastal Field Ecology. Bodega Marine Laboratory, University of California, Davis (1985-1991-one of two instructors).

International Experience:

I have worked and have active collaborations in Canada, Spain, Romania, Hungary, Germany, and Switzerland,  In the past I have also worked in Peru and Argentina.

Selected Publications:

Publications over last 5 years

Colautti, R.I., J.L. Maron and S.C.H. Barrett. 2009. Common garden comparisons of native and introduced plant populations: latitudinal clines can obscure evolutionary inference. Evolutionary Applications 2: 187-199.

Johnson, M.T.J., A. Agrawal, J.L. Maron and J-P. Salminen. 2009. Heritability, covariation and natural selection on 24 traits of common evening primrose (Oenothera biennis) from a field experiment. Journal of Evolutionary Biology 22: 1295-1307.

Seifert, E.K., J.D. Bever and J.L. Maron. 2009. Evidence for the evolution of reduced mycorrhizal dependence during plant invasion. Ecology 90: 1055-1062.

Brodie, J., O.E. Helmy and W.Y. Brockelman and J.L. Maron. 2009. Functional differences within a guild of tropical mammalian frugivores. Ecology 90:688-698.

Maron, J.L. and M. Marler. 2008. Field based competitive impacts of invaders on natives at varying resource supply. Journal of Ecology 96: 1187-1197.

Williams, J.L., H. Auge, and J.L. Maron. 2008. Different gardens, different results: Native and introduced populations exhibit contrasting phenotypes across common gardensOecologia 157: 239-248.

Maron, J.L. and M. Marler. 2008. Effects of native species diversity and resource additions on invader impact. American Naturalist 172: S18-S33.

Kittelson, P.M., J.L. Maron and M. Marler. 2008. Native diversity and invader impact: an exotic alters the leaf traits of two natives. Ecology 89: 1344-1351.

Other Publications:

Maron, J.L., J.K. Combs and S.L. Louda. 2002. Convergent demographic effects of insect herbivory on related thistles in coastal vs. continental dunes. Ecology 83:3382-3392.

Karban, R. and J.L. Maron. 2002. The fitness consequences of interspecific eavesdropping between plants. Ecology 83:1209-1213.

Kittelson, P.M. and J.L. Maron. 2001. Fine scale genetically-based differentiation of life-history traits in the perennial shrub, Lupinus arboreus. Evolution 55:2429-2438.

Maron, J.L. and M. Vilà. 2001. Do herbivores affect plant invasion? Evidence for the natural enemies and biotic resistance hypotheses. Oikos 95:363-373.

Maron, J.L. and R.L. Jefferies. 2001. Restoring enriched grasslands: effects of mowing on species richness, productivity and nitrogen retention. Ecological Applications 11:1088-1100.

Maron, J.L. and E.L. Simms. 2001. Rodent limited establishment of bush lupine: Field experiments on the cumulative effect of granivory. Journal of Ecology 89:578-588.

Maron, J.L., S. Harrison, and M.E. Greaves. 2001. Origin of an insect outbreak: escape in space or time from natural enemies? Oecologia 126:595-602.

Maron, J.L. 2001. Intraspecific competition and subterranean insect herbivory: individual and interactive effects on bush lupine. Oikos 92:178-186.

Harrison, S., K.J. Rice and J.L. Maron. 2001. Habitat patchiness promotes invasion by alien grasses (Avena fatua and Bromus hordeaceus) on serpentine soil in California. Biological Conservation 100:45-53.

Alpert, P. and J.L. Maron. 2000. Carbon addition as a countermeasure against biological invasion by plants. Biological Invasions 2:33-40.

Polis, G.A., D.R. Strong, G.R. Huxel, A.L.W. Sears and J.L. Maron. 2000. When is a trophic cascade a trophic cascade? Trends in Ecology and Evolution 15:473-475.

Maron, J.L. and S.N. Gardner. 2000. Consumer pressure, seed versus safe-site limitation, and plant population dynamics. Oecologia 124:260-269.

Harrison, S., J.L. Maron and G. Huxel. 2000. Local extinction, colonization and large-scale patterns of fluctuation in five plants confined to serpentine seeps. Conservation Biology 14:769-779.

Kittelson, P.M. and J.L. Maron. 2000. Outcrossing rate and inbreeding depression in the perennial yellow bush lupine, Lupinus arboreus (Fabaceae). American Journal of Botany 87:652-660.

Grosholz, E.D., G.M. Ruiz, C.A. Dean, K.A. Shirley, J.L. Maron and P.G. Connors. 2000. The impacts of a non-indigenous marine predator in a California bay.  Ecology 81:1206-1224.

Maron, J.L. and R.L. Jefferies. 1999. Bush lupine mortality, altered resource availability and alternative vegetation states. Ecology 80:443-454.

Maron, J.L. 1998. Individual and joint effects of below- and above-ground insect herbivory on perennial plant fitness. Ecology 79:1281-1293.

Maron, J.L. and S. Harrison. 1997. Spatial pattern formation in an insect host-parasitoid system. Science 278:1619-1621.

Maron, J.L. and E.L. Simms. 1997. Effects of seed predation on seed bank size and seedling recruitment of bush lupine (Lupinus arboreus). Oecologia 111:76-83.

Maron, J.L. 1997. Interspecific competition and insect herbivory reduce seedling survival in bush lupine, Lupinus arboreus. Oecologia 110:285-290.

Jefferies, R.L. and J.L. Maron. 1997. An embarrassment of riches: anthropogenic deposition of nitrogen and community and ecosystem processes. Trends in Ecology and Evolution 12:74-78.

Strong, D.R., H.K. Kaya, A. Whipple, A. Child, S. Kraig, M. Bondonno, K. Dyer, and J.L. Maron. 1996. Entomopathogenic nematodes: natural enemies of root-feeding caterpillars on bush lupine. Oecologia 108:167-173.

Maron, J.L. and P.G. Connors. 1996. A native nitrogen-fixing shrub facilitates weed invasion. Oecologia 105:302-312.

Strong, D.R., J.L. Maron, and P.G. Connors. 1996. Top down from underground? The underappreciated influence of subterranean food webs on above ground ecology. In Food Webs (G. A. Polis and K. O. Winemiller, eds.), pp 170-175. Chapman and Hall, New York.

Strong, D.R., J.L. Maron, P.G. Connors, A. Whipple, S. Harrison, and R.L. Jefferies. 1995. High mortality, fluctuation in numbers, and heavy subterranean insect herbivory in bush lupine, Lupinus arboreus. Oecologia 104:85-92.

Harrison, S. and J.L. Maron. 1995. Impacts of defoliation by tussock moths (Orgyia vetusta) on the growth and reproduction of bush lupine (Lupinus arboreus). Ecological Entomology 20:223-229.

Johnson, O.W., P.G. Connors, P.L. Bruner, and J.L. Maron. 1993. Breeding ground fidelity and mate retention in the Pacific Golden-plover. Wilson Bulletin 105:60-67.

Connors, P.G., B.J. McCaffery and J.L. Maron. 1993. Speciation in golden-plovers, Pluvialis dominica and Pluvialis fulva: evidence from the breeding grounds. Auk 110:9-20.

Myers, J.P., M. Sallaberry A., E. Ortiz, G. Castro, L.M. Gordon, J.L. Maron, C.T. Schick, E. Tabilo, P. Antas, and T. Below. 1990. Migration routes of New World sanderling (Calidris alba). Auk: 107:172-180.

Maron, J.L. and J.P. Myers. 1985. Seasonal changes in feeding success, activity patterns, and weights of non-breeding sanderlings, (Calidris alba). Auk 102:580-586.

Maron, J.L. and J.P. Myers. 1984. An evaluation of two techniques for sexing wintering sanderlings (Calidris alba). Journal of Field Ornithology 55:336-342.

Myers, J.P, J.L. Maron, and M. Sallaberry. 1984. Going to extremes: why sanderlings migrate to the neotropics. Ornithological Monographs 36:520-535.

Myers, J.P., G. Castro, B. Harrington, M. Howe, J.L Maron, E. Ortiz, M. Sallaberry, C.T. Schick, and E. Tabilo. 1984. The Pan American Shorebird Program: a progress report. Wader Study Group Bulletin 42:26-30.

Myers, J.P., J.L. Maron, E. Ortiz T., G. Castro V., M.A. Howe, R.I.G. Morrison, and B.A. Harrington. 1983. Rationale and suggestions for a hemispheric color-marking scheme for shorebirds: A way to avoid chaos. Wader Study Group Bulletin 38:30-32.