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Biology Department

Josh Ness

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Associate Professor @ Skidmore since 2005

Biology Department & Environmental Studies Program


Dana Science Center 319


(518) 580-5080



Our group explores the intersection of among-species interactions, invasion ecology and landscape science. I teach foundational courses in both Biology and Environmental Science, advanced courses focused on Conservation and Use of Forested Landscapes (ES205), Plant -Animal Interactions (BIO 339) and Biological Invasions (BIO 351), and a seminar for first year students called Life in the North Woods. Students perform exploratory research in all my courses, and I've co-authored four articles with undergraduates in the past five years. We use plants that rely on animals for dispersal and protection against natural enemies as model systems, and address questions by studying native and exotic species in New England forests (such as Skidmore College's North Woods ), the river network of the Upper Hudson watershed, and the Sonoran Desert (at Tumamoc Hill, in Arizona.)

Research Concentrations:

Plant - Animal Mutualisms. How do the dynamics of mutually beneficial interactions between plants and animals "work"? What are the consequences for populations and communities when interactions are disrupted by changes in community composition?

Landscape Ecology. How does landscape history, edge effects and spatial pattern modify the incidence of antagonistic, neutral and mutalistic interactions? How do the characteristics of neighbors influence a focal individual's experience in "mutualism marketplaces"?

Food as a motivation tool. How does the composition, production rate and presentation of food alter the behavior and performance and distribution of consumers? This work has focused on animals consuming plant-produced food rewards that either mimic meat (to encourage collection by omnivores) or elicit greater preference for meat (to encourage omnivores to turn their attention towards attacking herbivores).

Biotic Responses to Climatic Variation. The variation among seasons and among years is obvious in the deciduous forest of New Enclgand and the desert landscapes of Arizona. For example upstate New York experienced a record lack of snow in the 2011-12 winter, July 2005 was the warmest month recorded in Tucson since 1894. We monitor the phenology of fruit and nectar production by plants, and explore whether variation in the timing of reward production by plants, production has consequences for the plant and animal communities.


PUBLICATIONS * indicates undergraduate co-author

Ford, K.R., J.H. Ness, J.L. Bronstein and W.F. Morris (2015) Demographic consequences of mutualism: integrating multiple effects of ants on the population dynamics of a partner plant. Oecologia.

Ness, J.H., M.A. Morales, E. Kenison*, E. LeDuc*, P. Leipzig-Scott*, E. Rollinson*, B.J. Swimm* and D.R. VonAllmen* (2012). Reciprocally beneficial interactions between introduced plants and ants are induced by the presence of a third introduced species. Oikos (pdf)

Ness J.H., E.J. Rollinson* and K.D. Whitney. (2011) Phylogenetic distance can predict susceptibility to attack by natural enemies. Oikos (pdf)

Ness J.H., K. Mooney and L. Lach (2010) Ants as mutualists. Ch 6 in (Lach L, CL Parr and K Abbott, eds.) Ant Ecology. Oxford University Press, Oxford. (pdf)

Ness, J.H., W.F. Morris and J.L. Bronstein (2009) For ant-protected plants, the best defense is a hungry offense. Ecology 90: 2823-2831 (pdf)

Ness, J.H., D.F. Morin* and I. Giladi (2009) Uncommon specialization in a mutualism between a temperate herbaceous plant guild and an ant: Are Aphaenogaster ants keystone mutualists? Oikos 118: 1793-1804 (pdf)

Ness, J.H. and D. Morin* (2008) Forest edges and landscape history shape interactions between plants, seed-dispersing ants and seed predators. Biological Conservation 141: 838-847 (pdf)

Bronstein, J.L. and J.H. Ness (2007) 'Friends of Friends? Barrel cactus and its interacting mutualists'. The Arizona Native Plant Society's Plant Press 31: 8-10

Ness, J.H., W.F. Morris & J.L. Bronstein. (2006) Variation in mutualistic potential among ant species tending extrafloral nectaries of Ferocactus wislizeni . Ecology 87: 912-921 (pdf)

Ness, J.H. (2006) A mutualism's indirect costs: The most aggressive plant bodyguards also deter pollinators. Oikos 113: 506-514 (pdf)

Morris, W.F., W.G. Wilson, J.L. Bronstein & J.H. Ness. (2005) Environmental forcing and the temporal dynamics of a competitive guild of cactus-tending ants. Ecology 86: 3190-3199 (pdf)

Ness, J.H. & K. Bressmer* (2005) Abiotic influences on the behavior of rodents, ants, and plants affect an ant-seed mutualism. Ecoscience 12: 76-81 (pdf)

Holland, J.N., J.H. Ness, A. Boyle & J.L. Bronstein (2005) Mutualisms as consumer-resource interactions. Pp 17-33 In (P. Barbosa and I. Castellanos, eds.) Ecology of Predator - Prey Interactions . Oxford University Press, New York

Ness, J.H., J.L. Bronstein, A.N. Andersen & J.N. Holland (2004) Ant body size predicts dispersal distance of ant-adapted seeds: implications of small-ant invasions. Ecology 85: 1244-1250 (pdf)

Ness, J.H. (2004) Forest edges and fire ants alter the seed shadow of an ant-dispersed plant. Oecologia 138: 228-454 (pdf)

Ness, J.H. & J.L. Bronstein (2004) The effects of invasive ants on prospective ant mutualists. Biological Invasions 6: 445-461

Holland, J.N., R. Wyatt, J.L. Bronstein & J.H. Ness (2004) Relating the biology of flower-to-fruit survivorship to the ecology and evolution of fruit-to-flower ratios. Recent Research Developments in Plant Science 1: 75-84

Ness, J.H. (2003) Catalpa bignonioides alters extrafloral nectar production after herbivory and attracts ant bodyguards. Oecologia 134: 210-218 (pdf)

Ness, J.H. (2003) Contrasting exotic Solenopsis invicta and native Forelius pruinosus ants as mutualists with Catalpa bignonioides , a native plant. Ecological Entomology 28: 247-251 (pdf)

Ness, J.H. & S. A. Foster. (1999) Parasite mediated phenotype modifications in the threespine stickleback. Oikos 85: 127-134 (pdf)

Windsor, D., J. Ness , L.D. Gomez & P.H. Jolivet. (1999) Species of Aulacoscelis Duponchel and Chevrolat (Chrysomelidae) and Nomotus Gorham (Languriidae) feed on fronds of Central American cycads. The Coleopterist Bulletin 53: 217-231.