John Maron

Photo of Maron, John

John Maron


Curriculum Vitae: View/Download CV

Office Hours:

Tuesday, Thursday 12:30-1:30

Personal Summary

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


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.

Courses Taught

Fall 08-BIOL448

Teaching Experience

Conservation Ecology (Undergraduate lecture course)  2014
Graduate Policies and Regulations (Graduate discussion course)  2008-2011
Population and Community Ecology (Graduate lecture & discussion course; one of two instructors).   2010, 2011, 2013
Population Biology (Graduate lecture & discussion course; one of two instructors). 2009
Terrestrial Plant Ecology (Undergraduate lecture & discussion course).  2002-08, 2010
Rocky Mountain Flora (Undergraduate lecture & laboratory course).  2005, 2007, 2009
Plant-Consumer Interactions (Graduate lecture & discussion course).   2004, 2008, 2011
Intro. Biology (Undergraduate lecture & laboratory course; one of four instructors). 2003
Trends in Plant Ecology, (Graduate seminar course; one of two instructors).   2003


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. 

Field of Study

Plant population and community ecology

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

Brodie, J.F., C.E. Aslan, H.S. Rogers, K.H. Redford, J.L. Maron, J.L. Bronstein, and C.R. Groves.  In Press.  Secondary extinctions of biodiversity.  Trends in Ecology and Evolution.

Maron, J.L., K. Baer and A.L. Angert. In Press.  Disentangling the drivers of context-dependent plant-animal interactions. Journal of Ecology.

Palladini, J.D. and J.L. Maron.  In Press.  Demographic responses of a solitary bee to floral resource gradients created by native and invasive plants.  Oecologia.

Pinto, S.M., D.E. Pearson and J.L. Maron.  2014.  Seed dispersal is more limiting to native grassland diversity than competition or seed predation.  Journal of Ecology 102: 1258-1265.

Maron, J.L., H. Auge, D.E. Pearson, L. Korell, I. Hensen, K. Suding, and C. Stein.  2014.  Staged invasions across disparate grasslands:  effects of seed provenance, consumers, and disturbance on productivity and species richness.  Ecology Letters 17: 499-507.

Molins, M.P., J.M. Corral, O.M. Aliyu, M.A. Koch, A. Betzin, J.L. Maron and T.F. Sharbel.  2014.  Biogeographic variation in genetic variability, apomixes expression and ploidy of St. John’s wort (Hypericum perforatum L.) across its native and introduced range.  Annals of Botany 113: 417-427.

Maron, J.L., J. Klironomos, L. Waller and R.M. Callaway. 2014.  Invasive plants escape from suppressive soil biota at regional scales.  Journal of Ecology 102: 19-27.

Palladini, J.D. and J.L. Maron.  2013.  Indirect competition for pollinators is weak compared to direct resource competition: pollination and performance in the face of a potent invader.  Oecologia 172: 1061-1069.

Maron, J.L., L. Waller, M. Han, A. Diaconu, R. Pal, H. Müller-Schärer, and R.M. Callaway.  2013.  Effects of soil pathogens, disturbance, propagule pressure and competition on exotic plant recruitment at home and abroad.  Journal of Ecology 101: 924-932.

Callaway, R.M., D. Montesinos, K. Williams, and J.L. Maron.  2013.  Native congeners provide biotic resistance to invasive Potentilla through soil biota.  Ecology 94: 1223-1229.

Parsons, E.W.R., J.L. Maron and T. Martin.  2013.  Elk herbivory alters small mammal assemblages in high-elevation drainages.  Journal of Animal Ecology 82: 459-467.

Agrawal, A.A., M.T.J. Johnson, A.P. Hastings, and J.L. Maron.  2013.  A field experiment demonstrating plant life-history evolution and its eco-evolutionary feedback to seed predator populations.  American Naturalist 181: S35-S45.

Karban, R., P. Grof-Tisza, J.L. Maron and M. Holyoak.  2012.  The importance of host plant limitation for caterpillars (Platyprepia virginalis) varies spatially.  Ecology 93: 2216-2226.

Pearson, D., T. Potter and J.L. Maron.  2012.  Biotic resistance: exclusion of native rodent consumers releases populations of a weak invader.  Journal of Ecology 100:1383-1390.

Maron, J.L., T. Potter, Y. Ortega, and D. Pearson.  2012.  Seed size and evolutionary origin mediate the impacts of disturbance and rodent seed predation on community assembly.  Journal of Ecology 100:1492-1500.

Agrawal, A.A., A.P. Hastings, M.T. Johnson, J.L. Maron, and J-P. Salminn.  2012.  Insects as drivers of community and evolutionary change.  Science 338: 113-116. 

Callaway, R.M., U. Schaffner, G.C. Thelen, A. Khamraev, T. Juginisov and J.L. Maron.  2012. Impact of Acroptilon repens on co-occurring native plants is greater in the invader’s non- native range.  Biological Invasions 14:1143-1155.

Ortega, Y.K., D.E. Pearson, L.P. Waller, N.J. Sturdevant, and J.L. Maron.  2012.  Population-level compensation impedes biological control of an invasive forb and indirect release of a native grass.  Ecology 93:783-792.

Martin, T.E. and J.L. Maron.  2012.  Climate impacts on bird and plant communities from an altered plant-animal interaction.  Nature Climate Change 2: 195-200. 

Bricker, M. and J.L. Maron.  2012.  Seed predation lowers population growth rate in a long-lived perennial forb (Lithospermum ruderale).  Ecology 93:532-543.

Callaway, R.M., L.P. Waller, A. Diaconu, R. Pal, A.R. Colllins, H. Müller-Schärer and J.L. Maron.  2011.  Escape from competition: Neighbors reduce C. stoebe performance at home but not away.  Ecology 92: 2208-2013.

Huntzinger, M., R. Karban and J.L. Maron.  2011.  Small mammals cause non-trophic effects on habitat and associated snails in a native system. Oecologia 167:1085-1091.

Pearson, D.E., R.M. Callaway and J.L. Maron.  2011.  Biotic resistance via post-dispersal seed predation: establishment by invasive, naturalized, and native Asters reflects generalist granivore preferences.  Ecology 92:1748-1757.

Maron, J.L. and D.E. Pearson.  2011.  Vertebrate predators have minimal cascading indirect effects on plant production in an intact grassland ecosystem.  Ecology Letters 14:661-669.

Vilà, M., J.M. Espinar, M. Hejda, P.E. Hulme, V. Jarošík,  J.L. Maron, J. Pergl, P. Pyšek, U. Schaffner, and Y. Sun.  2011.  Ecological impacts of plant invaders.  Ecology Letters 14:702-708.

Maron, J.L., M. Marler, J. Klironomos, and C. Cleveland.  2011.  Soil pathogens contribute to the positive plant diversity-productivity relationship.  Ecology Letters 14: 36-41. 

Maron, J.L., D.E. Pearson and R. Fletcher Jr.  2010.  Counter-intuitive effects of large-scale predator removal on a mid-latitude rodent community.  Ecology 91: 3719-3729.

Williams, J.L., H. Auge, and J.L. Maron.  2010.  Effects of disturbance and herbivory on invasive plant abundance at home and abroad.  Ecology 91: 1355-1366.

Bricker, M., D. Pearson and J.L. Maron.  2010.  Small mammal seed predation limits the recruitment and abundance of two perennial grassland forbs.  Ecology 91: 85-92.

Maron, J.L., C.C. Horvitz and J.L. Williams.  2010.  Using experiments, demography and population models to estimate interaction strength based on transient and asymptotic dynamics.  Journal of Ecology 98: 290-301.

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.

Brodie, J., O.E. Helmy, W.Y. Brockelman and J.L. Maron.  2009.  Bushmeat poaching reduces the seed dispersal and population growth rate of a mammal-dispersed tree.  Ecological Applications 19: 854-863.

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.