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Diane (Dinah) Davidson

Professor Emerita


Research Statement


Ant-plant relationships are used as model systems to study the evolution of specialization in interspecific interactions. Thousands of plant species produce homes and/or nutritional rewards which induce ants to protect plant tissues from herbivory, to disperse seeds, and/or to supply essential nutrients. Evolutionary specialization and species-specificity are greatest in the symbiotic relationships of ants with myrmecophytic tropical trees, shrubs and epiphytes. Striking similarities among myrmecophyte-ant relationships on different continents are not due to common ancestry. Rather, preadaptations have facilitated the frequent evolution of ant-plants and plant-ants. The resource environments of plants, and competition among ants for hosts, have driven strong parallel and convergent evolution in preadapted lineages of plants and ants, respectively. Plant investment in biotic (ant) defenses correlates strongly with plant resource regimes and appears typically not to have coevolved with specific ants. Although phylogenetic analyses of plants and ants are unlikely to reveal tight cospeciation, they may reveal regular trajectories in the evolutionary diversification and condensation of lineages. For example, ants may be subject to "taxon cycles" in which genera first diversify and radiate onto many hosts, and eventually are driven by new and more competitive taxa to increased specialization, narrower distributions, and extinction. Dietary effects on the ecology and evolution of ants (Formicidae) (funded by the National Science Foundation) In lowland tropical rain forests, ants can comprise up to 94% of individuals and 86% of biomass in canopy arthropod samples. Although commonly viewed as predators and scavengers, ants are regularly more abundant than their supposed prey. Extraordinary abundance usually characterizes just 1 or 2 ant species (per sample) which depend strongly on carbohydrate-rich plant and homopteran exudates for food. Though % nitrogen of exudates is low, lower _15N values in these ants than in predatory species indicate that the former obtain more of their (growth-limiting) nitrogen at a lower trophic level than do predators. Lower % dry weight N in exudate- feeders than in predators (large-bodied ants only) may indicate lesser investment in protein-rich exoskeleton. Diets of abundant species have high CHO: protein ratios. CHOs in excess of those paired with protein for colony growth and reproduction may be directed at little cost to: (1) high tempo activities, correlated with high "dynamic densities" and rapid protein discovery; (2) defense of absolute territories (rare in ants, but more common in exudate-feeders), and (3) offensive and defensive exocrine products. Character mapping onto an ant phylogeny indicates that ants have switched from N-containing proteinaceous or alkaloidal venoms to N-free chemicals at least 4 independent times, coincident with changes in digestive morphology. We are currently conducting experimental and comparative tests of the effects of dietary CHO:N ratio on ant behavior and exocrine chemistry. Integrative studies of territoriality in rainforest ants (originated with NSF funding; currently supported by the National Geographic Society; other proposals pending) Ants of Asian rain forests display a diversity of (sometimes spectacular) traits utilized in interspecific and intraspecific territorial contests. Working in Brunei Darussalam, and using a combination of molecular phylogenetic, chemical, behavioral, and other analytical tools, we are attempting to assess both factors contributing to the origin and maintenance of these characteristics and the consequences of such traits for arthropod diversity in rain forests. Multi-scale spatial patterning in the distributions of microbial soil crusts and their component organisms (funded by the U.S. Department of Agriculture) Microbiotic soil crusts, comprised of cyanobacteria, lichens, mosses and free-living algae and fungi, are common components of arid ecosystems, where they provide a variety of ecosystem services, e.g., nitrogen fixation, erosion control, and perhaps resistence to non-native weeds. Distributions of component organisms across the microaspects of soil pedicels suggest that a combination of abiotic and biotic factors might determine the distributions of these organisms at a hierarchy of spatial scales. Requirements for particular microsites differing in climate and soil properties may also help to explain why recovery of disturbed soil crusts is so slow, because pedicelation of crusts occurs gradually. Degree of alignment of pedicels to the typical NNW-SSE axis may serve as a useful indicator of stage of recovery.

Specific Interests
  • Ant-Plant Coevolution

Selected Publications


  • Brown, J.H., J.J. Grover, D.W. Davidson and G.A. Lieberman 1975. A preliminary study of seed predation in desert and montane habitats. Ecology 56(4):987-992.
  • Davidson, D.W. 1977. Species diversity and community organization in desert seed-eating ants. Ecology 58:711-724. Reprinted in R. Patrick, ed. Diversity, Volume 11 of "Benchmark Papers in Ecology." (Partially reproduced in textbook, "Population Ecology" by M. E. Begon and A. M. Mortimer, Blackwell Scientific Publications).
  • Davidson, D.W. 1977. Foraging ecology and community organization in desert seed-eating ants. Ecology 58: 724-737.
  • Brown, J.H. and D.W. Davidson 1977. Competition between seed-eating rodents and ants in desert ecosystems. Science 196: 880-882.
  • Davidson, D.W. 1978. Worker size variation in a social insect as a function of the competitive environment. Am. Nat. 112:523-532. (Partially reproduced in books by [1] E.H. Miller, [2] A.J. Pontin, [3] M.E. Begon and A.M. Mortimer, and [4] Begon, Harper and Townsend).
  • Davidson, D.W. 1978. Experimental tests of optimal diet predictions in a social insect. Behav. Ecol. Sociob. 4:35-41.
  • Brown, J.H., O.J. Reichman and D.W. Davidson 1979. Granivory in desert ecosystems. Ann. Rev. Ecol. Syst. 10:201-27.
  • Brown, J.H., D.W. Davidson, and O.J. Reichman 1979. An experimental study of competition between seed-eating desert rodents and ants. Am. Zool. 19:1129-1143.
  • Davidson, D.W. 1980. Some consequences of diffuse competition in desert seed- eating ants. Am. Nat. 116 (7):92-105. (Tables reproduced in textbook, Population Biology: the Coevolution of Population Dynamics and Behavior by J.M. Emlen.)
  • Davidson, D.W., J.H. Brown and R.S. Inouye 1980. Competition and the structure of granivore communities. Bioscience 30:233-238.
  • Davidson, D.W., and S.R. Morton 1981. Myrmecochory in some plants (Chenopodiaceae) of the Australian arid zone. Oecologia 50:357-366.
  • Davidson, D.W. and S.R. Morton 1981. Competition for dispersal in ant- dispersed plants. Science 213:1259-1261. (Figure reproduced in textbook, Plant Ecology by M.J. Crawley, Chapter by H. Howe and L. Westley, 1986 Blackwell Scientific Publication).
  • Davidson, D.W. 1982. Sexual selection and reproductive allocation in the Pogonomyrmex (F. Formicidae). Behav. Ecol. Sociob. 10:245-250.
  • Jeanne, R.L. and D.W. Davidson 1984. Population regulation in social insects, Chapter 18 in Ecological Entomology (C.B. Huffaker and R.L. Rabb, eds.) Wiley- Interscience.
  • Davidson, D.W. and S.R. Morton 1984. Dispersal adaptations of some Acacia species in the Australian arid zone. Ecology 65:1038-51.
  • Davidson, D.W., R.S. Inouye and J.H. Brown 1984. Granivory in a desert ecosystem: experimental evidence for indirect facilitation of ants by rodents. Ecology 65:1780-1786.
  • Davidson, D.W. 1985. An experimental study of diffuse competition in harvester ants. Am. Nat. 125(4):500-506.
  • Davidson, D.W., D.A. Samson* and R.S. Inouye* 1985. Experimental studies of granivory in the Chihuahuan Desert: Interactions within and between trophic levels. Ecology 66(2):486-502.
  • Brown, J.H., D.W. Davidson, J.C. Munger* and R.S. Inouye* 1985. Experimental community ecology: the desert granivore system. In J. Diamond and T.J. Case (eds.) Community Ecology. Harper and Row Publishers, N.Y. (pp. 41-61).
  • Brown, J.H. and D.W. Davidson 1986. Reply to Galindo. Ecology 67:1423- 24.
  • Morton, S.R. and D.W. Davidson 1988. Comparative structure of harvester ant communities in arid Australia and North America. Ecol. Monogr. 58:19-38.
  • Davidson, D.W., J. Longino and R.R. Snelling 1988. Pruning of host plant neighbors by ants: an experimental approach. Ecology 69:801-808.
  • Davidson, D.W. 1988. Ecological studies of neotropical ant-gardens.- external site Ecology 69:1138-1152.
  • Davidson, D.W. and W.W. Epstein 1989. Epiphytic associations with ants. In U. L�ttge (ed.) Vascular Plants as Epiphytes. Springer-Verlag, N.Y., pp. 200-233.
  • Davidson, D.W., R.R. Snelling and J. Longino 1989. Competition among ants for myrmecophytes and the significance of plant trichomes. Biotropica 21:64- 73.
  • Seidel*, J.L., W.W. Epstein and D.W. Davidson 1990. Neotropical ant gardens: I. Chemical constituents of epiphytic fruits and seeds. J. Chem. Ecol. 16:1791-1816.
  • Davidson, D.W., J.L. Seidel* and W.W. Epstein 1990. Neotropical ant gardens: II. Bioassays of seed compounds. J. Chem. Ecol. 16:2993-3013.
  • Davidson, D.W., R. Foster, R.R. Snelling and P.W. Lozada 1991. Variable composition of some tropical ant-plant symbioses. In P.W. Price et al. (eds.), Herbivory: Tropical and Temperate Perspectives. John Wiley & Sons, New York, pp. 145-162.
  • Davidson, D.W. and B.L. Fisher* 1991. Symbiosis of ants with Cecropia as a function of light regime. In C.R. Huxley and D. Cutler (eds.), Ant- Plant Interactions, Oxford Univ. Press, pp. 289-309.
  • Samson, D.A.*, T. Philippi*, and D.W. Davidson 1992. Granivory and competition as determinants of annual plant diversity in the Chihuahuan Desert. Oikos 65: 61-80.
  • Johnson, H.**, D. Davidson and P. Folgarait* 1992. Experimental manipulation of food bodies in Cecropia. Proceedings of the National Conference on Undergraduate Research VI, pp. 1542-1547.
  • Davidson, D. W. 1993. The effects of herbivory and granivory on terrestrial plant succession. Oikos 68: 23-35.
  • McKey, D. and D. W. Davidson. 1993. Ant-plant symbioses in Africa and the Neotropics. In P. Goldblatt (ed.), Biological Relationships between Africa and South America. Yale Univ. Press, New Haven, CT. pp. 568-606.
  • Davidson, D. W. and D. McKey 1993. The evolutionary ecology of symbiotic ant- plant relationships.- external site J. Hym. Res. 2: 13-83.
  • Davidson, D. W. and D. McKey 1993. Ant-plant symbioses: stalking the Chuyachaqui. Trends Ecol. Evol. 8(9): 326-332.
  • Folgarait, P.*, H. Johnson** and D. W. Davidson 1993. Response of Cecropia to experimental removal of food bodies. Funct. Ecol. 8:22-28.
  • Folgarait, P.* and D. W. Davidson 1994. Biotic and chemical defenses of myrmecophytic Cecropia in different light regimes. Oikos 71: 305- 320.
  • Treseder, K.K.**, D. W. Davidson and J. R. Ehleringer 1995. Absorption of ant-provided carbon dioxide and nitrogen by Dischidia major (Asclepiadaceae), a tropical epiphyte. Nature 375:137-139 (and cover).
  • Folgarait, P.* and D. W. Davidson 1995. Myrmecophytic Cecropia: antiherbivore defenses in different nutrient regimes. Oecologia 104:189- 206.
  • Pinard, M.*, B. Howlett* and D. W. Davidson 1996. Site conditions limit pioneer tree establishment after logging of dipterocarp forests in Sabah, Malaysia. Biotropica 28: 2-12.
  • Davidson, D. W., W. D. Newmark, J. W. Sites, Jr., D. K. Shiozawa, E. A. Rickart, K. T. Harper, and R. B. Keiter 1996. Selecting wilderness areas to conserve Utah's biodiversity. The Gr. Bas. Nat. 56: 95-114.
  • Howlett, B.E.* and D. W. Davidson 1996. Dipterocarp seed and seedling performance in secondary logged forests dominated by Macaranga spp. Proceedings of the Fifth Round-Table Conference on Dipterocarps, Chiang Mai, Thailand, 7-10 November, 1994. Forest Research Institute of Malaysia, Kepong, Malaysia.
  • Davidson, D. W. and L. J. Patrell-Kim** 1996. Tropical arboreal ants: Why so abundant? A. Gibson, ed., Neotropical Biodiversity and Conservation. UCLA Herbarium Publ. 1., Los Angeles, pp. 127-140.
  • Yu, D. W.* and D. W. Davidson. 1997. Experimental studies of species- specificity in Cecropia-ant relationships. Ecol. Monogr. 67:273- 294.
  • Davidson, D. W. 1997. Resource imbalances and the evolutionary ecology of tropical arboreal ants.- external site Biol. J. Linn. Soc. 61: 153-181.
  • Pinard, M.*, D. Davidson and A. Ganing. 1998. Effects of trenching on growth and survival of planted Shorea parvifolia Dyer seedlings under pioneer stands in logged-over forests. J. Trop. For. Sci. 10(4): 505-515.
  • Davidson, D. W. 1998. Resource discovery versus resource domination in ants: breaking the trade-off. Ecol. Ent. 23: 484-490 (invited contribution to "New Perspectives" section)
  • Davidson, D. W. 1998. Non-native brome grasses in the new national monument. Pp. 161-172 in L.M. Hill (ed.), Learning from the Land, Grand Staircase- Escalante National Monumnet Science Symposium Proceedings, US Dept. of Interior, BLM. Proceedings of the First Scientific Conference on the Grand Staircase - Escalante National Monument, Cedar City, UT.
  • George, D. B.*, D. W. Davidson, K. C. Schliep**, and L. J. Patrell-Kim**. 2000. Microtopography of microbiotic crusts on the Colorado Plateau, and the distribution of component organisms. West. N. Amer. Nat. 60: 343-354.
  • Howlett, B. E.* and D. W. Davidson. 2000. Herbivory on planted dipterocarp seedlings in secondary logged forests and primary forests of Sabah, Malaysia.- external site J. Trop. Ecol. 17: 285-302.
  • Vasconcelos, H.L. and D.W. Davidson. 2000. Relationship between plant size and ant associate in two Amazonian ant-plants. Biotropica 32: 100-111.
  • Davidson, D.W., M. Bowker, D. George*, S.L. Phillips, and J. Belnap. 2002. Treatment effects on the performance of nitrogen-fixing Collema lichens in disturbed crusts of the Colorado Plateau. Ecol. Appl. 12:1391-1405
  • Davidson, D.W., S.C. Cook*, Roy R. Snelling and T.H. Chua. 2003. Explaining the abundance of ants in lowland tropical rainforest canopies. Science 300:969-972. (Publication is available at www.biology.utah.edu/davidson)
  • Howlett, B. E.* and D. W. Davidson. (2003) Effects of seed availability, site conditions, and herbivory on pioneer recruitment after logging in Sabah, Malaysia. Forest Ecol. Manage. 184: 369-383.
  • Davidson, D. W., Cook, S. C., and Snelling, R. R. 2004. Liquid-feeding performances of ants (Hymenoptera: Formicidae): ecological and evolutionary implications- external site. Oecologia 139: 255-266.
  • Davidson, D.W., S.C. Cook* and R.R. Snelling (2005) Liquid feeding performances in ants (Hymenoptera: Formicidae): ecological and evolutionary implications. Oecologia 143:335. Errata
  • Jones, T.H., D.A. Clark,** A. Edwards, D. W. Davidson, T.F. Spande, and R.R. Snelling (2004) The chemistry of exploding ants- external site , Camponotus spp. (cylindricus complex). J. Chem. Ecol. 30:1479-1492
  • Davidson, D.W. (2004) Ant - plant interactions. Pp. 103-120 in J. L. Capinera (ed.) Encyclopedia of Entomology. Kluwer, Dordrecht.
  • Davidson, D.W. (2005) Ecological stoichiometry of ants in a New World rain forest.- external site Oecologia 142:221-231.
  • Davidson, D. W. (2005) Cecropia and its biotic defenses. Pp. 214-226 in C. C. Berg and P. Franco Rosselli, Cecropia. Flora Neotropica, New York Botanical Garden, NY.
  • Jones, T.H., S.R. Brunner**, A. Edwards, D.W. Davidson and R.R. Snelling. (2005) 6-alkylsalicylic acids- external site from Crematogaster cf. difformis. J. Chem. Ecol. 31: 407-417.
  • Davidson, D.W., D.A. Clark,** and T.H. Jones (2005) Gastral exocrine products of myrmicine ants strongly overlap pygidial gland products of Dolichoderinae. Insectes Soc. 52:305-30.
  • Bowker, M.AB J. Belnap, D.W. Davidson, and S.L. Phillips (2005) Evidence for micronutrient limitation of biological soil crusts: potential to impact arid-lands restoration- external site. Ecol. Appl. 15: 1941-1951.
  • Cook, S.C.* and D.W. Davidson. (2006) Nutritional and functional biology of exudate-feeding ants (Hymenoptera: Formicidae)- external site . Entom. Exp. Appl 118:1-10.
  • Davidson, D.W., J.A. Arias, and J. Mann. (2006) An experimental study of bamboo ants in Western Amazonia.- external site Insectes Soc 51:108-104.
  • Bowker, M.A., J. Belnap, D.W. Davidson, and H. Goldstein (2006) Correlates of biological soil crust distribution across a continuum of spatial scales: support for a hierarchical conceptual model- external site. J. Appl. Ecol. 43:152-163.
  • Davidson, D.W., S.D. Castro, J.A. Arias, and J. Mann (2006) Unveiling a ghost of Amazonian rain forests: Camponotus mirabilis, engineer of Guadua bamboo- external site. Biotropica 38:653-660.
  • Jones, T.H., H.L. Voegtle, H.M. Miras, R.G. Weatherford, T.F. Spande, H.M. Garraffo, J.W. Daly, D.W. Davidson, and R.R. Snelling. (2007) The venom chemistry of the ant Myrmicaria melanogaster from Brunei- external site J. Nat. Prod. 70:160-168.
  • Davidson, D.W., J-P. Lessard,B C.R. Bernau,** and S.C. Cook.* (2007) The tropical ant mosaic in a primary Bornean rain forest.- external site Biotropica 39:468-475.
  • Voegtle, H.L., T.H. Jones, D.W. Davidson, and R.R. Snelling. (2008) E-2-ethylhexenal, E-2-ethyl-2-hexenol, mellein, and 4-hydroxymellein in Camponotus species from Brunei.- external site J. Chem. Ecol. 34:215-219.
  • Davidson, D.W. and S.C. Cook.* (2009) Tropical Arboreal Ants: Linking Nutrition to Roles in Rainforest Ecosystems .- external site In W.P. Carson and S.A. Schnitzer (eds) Tropical Forest Community Ecology. Blackwell Science Publ., London.
  • Davidson, D.W.,� N.F. Anderson**, S.C. Cook*, C.R. Bernau**, T.H. Jones, A.S. Kamariah, L.B. Lim, C.M. Chan, and D.A. Clark**. (2009) An experimental study of microbial nest associates of Borneo�s exploding ants (Camponotus [Colobopsis] species).- external site� J. Hym. Res. 18: 341-360.
  • Bowker, M.A.*, J. Belnap, and D.W. Davidson.� (2009)� Microclimate and propagule availability are equally important for rehabilitation of dryland N-fixing lichens.� Restor. Ecol. 18: 30-33.