You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:


Log in to your personal account or through your institution.

More than “More Individuals”: The Nonequivalence of Area and Energy in the Scaling of Species Richness

Allen H. Hurlbert and Walter Jetz
The American Naturalist
Vol. 176, No. 2 (August 2010), pp. E50-E65
DOI: 10.1086/650723
Stable URL:
Page Count: 16
Subjects: Biological Sciences Ecology & Evolutionary Biology
  • Download PDF
  • Add to My Lists
  • Cite this Item
More than “More Individuals”: The Nonequivalence of Area and Energy in the Scaling of Species Richness
We're having trouble loading this content. Download PDF instead.


Abstract: One of the primary ecological hypotheses put forward to explain patterns of biodiversity is known as the more‐individuals hypothesis of species‐energy theory. This hypothesis suggests that the number of species increases along the global energy gradient primarily as a result of an increase in the total number of individuals that can be supported along that gradient. Implicit in this hypothesis is that species richness should scale with energy in the same way in which it scales with area in species‐area relationships. We developed a novel framework for thinking about the interaction of area and energy, and we provide the first global test of this equivalence assumption using a data set on terrestrial breeding birds. We found that (1) species‐energy slopes are typically greater than species‐area slopes, (2) the magnitude of species‐area and species‐energy slopes varies strongly across the globe, and (3) the degree to which area and energy interact to determine species richness depends on the way mean values of species occupancy change along the energy gradient. Our results indicate that the increase in richness along global productivity gradients cannot be explained by more individuals alone, and we discuss other mechanisms by which increased productivity might facilitate species coexistence.

Notes and References

This item contains 70 references.

Literature Cited
  • ['Abrams, P. A. 1995. Monotonic or unimodal diversity‐productivity gradients: what does competition theory predict? Ecology 76:2019–2027.']
  • ['Arita, H. T., J. A. Christen, P. Rodríguez, and J. Soberón. 2008. Species diversity and distribution in presence‐absence matrices: mathematical relationships and biological implications. American Naturalist 172:519–532.']
  • ['Bolnick, D. I., R. Svanback, J. A. Fordyce, L. H. Yang, J. M. Davis, C. D. Hulsey, and M. L. Forister. 2003. The ecology of individuals: incidence and implications of individual specialization. American Naturalist 161:1–28.']
  • ['Bondeau, A., P. C. Smith, S. Zaehle, S. Schaphoff, W. Lucht, W. Cramer, D. Gerten, et al. 2007. Modelling the role of agriculture for the 20th century global terrestrial carbon balance. Global Change Biology 13:679–706.']
  • ['Bonn, A., D. Storch, and K. J. Gaston. 2004. Structure of the species‐energy relationship. Proceedings of the Royal Society B: Biological Sciences 271:1685–1691.']
  • ['Brown, J. H. 1981. Two decades of homage to Santa‐Rosalia: toward a general theory of diversity. American Zoologist 21:877–888.']
  • ['Burnham, K. P., and D. R. Anderson. 2002. Model selection and multi‐model inference: a practical information‐theoretic approach. Springer, New York.']
  • ['Connor, E. F., and E. D. McCoy. 1979. The statistics and biology of the species‐area relationship. American Naturalist 113:791–833.']
  • ['Currie, D. J. 1991. Energy and large‐scale patterns of animal and plant species richness. American Naturalist 137:27–49.']
  • ['Drakare, S., J. J. Lennon, and H. Hillebrand. 2006. The imprint of the geographical, evolutionary and ecological context on species‐area relationships. Ecology Letters 9:215–227.']
  • ['Evans, K. L., P. H. Warren, and K. J. Gaston. 2005. Species‐energy relationships at the macroecological scale: a review of the mechanisms. Biological Reviews 80:1–25.']
  • ['Evans, K. L., S. E. Newson, D. Storch, J. J. D. Greenwood, and K. J. Gaston. 2008. Spatial scale, abundance and the species‐energy relationship in British birds. Journal of Animal Ecology 77:395–405.']
  • ['Francis, A. P., and D. J. Currie. 2003. A globally consistent richness‐climate relationship for angiosperms. American Naturalist 161:523–536.']
  • ['Gaston, K. J., S. L. Chown, and K. L. Evans. 2008. Ecogeographical rules: elements of a synthesis. Journal of Biogeography 35:483–500.']
  • ['Green, J. L., and A. Ostling. 2003. Endemics‐area relationships: the influence of species dominance and spatial aggregation. Ecology 84:3090–3097.']
  • ['Harte, J., and A. P. Kinzig. 1997. On the implications of species‐area relationships for endemism, spatial turnover, and food web patterns. Oikos 80:417–427.']
  • ['Harte, J., E. Conlisk, A. Ostling, J. L. Green, and A. B. Smith. 2005. A theory of spatial structure in ecological communities at multiple spatial scales. Ecological Monographs 75:179–197.']
  • ['Hawkins, B. A., R. Field, H. V. Cornell, D. J. Currie, J. F. Guegan, D. M. Kaufman, J. T. Kerr, et al. 2003. Energy, water, and broad‐scale geographic patterns of species richness. Ecology 84:3105–3117.']
  • ['Hawkins, B. A., J. A. F. Diniz‐Filho, L. M. Bini, P. De Marco, and T. M. Blackburn. 2007. Red herrings revisited: spatial autocorrelation and parameter estimation in geographical ecology. Ecography 30:375–384.']
  • ['He, F. L., and P. Legendre. 2002. Species diversity patterns derived from species‐area models. Ecology 83:1185–1198.']
  • ['Hixon, M. A. 1980. Food production and competitor density as the determinants of feeding territory size. American Naturalist 115:510–530.']
  • ['Holmes, R. T., R. E. Bonney, and S. W. Pacala. 1979. Guild structure of the Hubbard Brook bird community: a multivariate approach. Ecology 60:512–520.']
  • ['Hurlbert, A. H. 2004. Species‐energy relationships and habitat complexity in bird communities. Ecology Letters 7:714–720.']
  • ['Hurlbert, A. H., and W. Jetz. 2007. Species richness, hotspots, and the scale dependence of range maps in ecology and conservation. Proceedings of the National Academy of Sciences of the USA 104:13384–13389.']
  • ['Hurlbert, A. H., and E. P. White. 2005. Disparity between range map‐ and survey‐based analyses of species richness: patterns, processes and implications. Ecology Letters 8:319–327.']
  • ['———. 2007. Ecological correlates of geographic range occupancy in North American birds. Global Ecology and Biogeography 16:764–773.']
  • ['Jetz, W., D. S. Wilcove, and A. P. Dobson. 2007. Projected impacts of climate and land‐use change on the global diversity of birds. PLoS Biology 5:1211–1219.']
  • ['Jetz, W., H. Kreft, G. Ceballos, and J. Mutke. 2009. Global associations between terrestrial producer and vertebrate consumer diversity. Proceedings of the Royal Society B: Biological Sciences 276:269–278.']
  • ['Kallimanis, A. S., A. D. Mazaris, J. Tzanopoulos, J. M. Halley, J. D. Pantis, and S. P. Sgardelis. 2008. How does habitat diversity affect the species‐area relationship? Global Ecology and Biogeography 17:532–538.']
  • ['Kalmar, A., and D. J. Currie. 2006. A global model of island biogeography. Global Ecology and Biogeography 15:72–81.']
  • ['———. 2007. A unified model of avian species richness on islands and continents. Ecology 88:1309–1321.']
  • ['Kaspari, M., S. O’Donnell, and J. R. Kercher. 2000. Energy, density, and constraints to species richness: ant assemblages along a productivity gradient. American Naturalist 155:280–293.']
  • ['Koleff, P., K. J. Gaston, and J. J. Lennon. 2003. Measuring beta diversity for presence‐absence data. Journal of Animal Ecology 72:367–382.']
  • ['Kreft, H., and W. Jetz. 2007. Global patterns and determinants of vascular plant diversity. Proceedings of the National Academy of Sciences of the USA 104:5925–5930.']
  • ['Lyons, S. K., and M. R. Willig. 2002. Species richness, latitude, and scale sensitivity. Ecology 83:47–58.']
  • ['MacArthur, R. H. 1972. Geographical ecology. Princeton University Press, Princeton, NJ.']
  • ['MacArthur, R. H., and J. W. MacArthur. 1961. On bird species diversity. Ecology 42:594–598.']
  • ['MacArthur, R. H., and E. O. Wilson. 1967. The theory of island biogeography. Princeton University Press, Princeton, NJ.']
  • ['Martin, H. G., and N. Goldenfeld. 2006. On the origin and robustness of power‐law species‐area relationships in ecology. Proceedings of the National Academy of Sciences of the USA 103:10310–10315.']
  • ['May, R. M. 1975. Patterns of species abundance and diversity. Pages 81–120 in M. L. Cody, and J. M. Diamond, eds. Ecology and evolution of communities. Harvard University Press, Cambridge, MA.']
  • ['McGill, B. 2003. Strong and weak tests of macroecological theory. Oikos 102:679–685.']
  • ['McGill, B., and C. Collins. 2003. A unified theory for macroecology based on spatial patterns of abundance. Evolutionary Ecology Research 5:469–492.']
  • ['Olson, D. M., E. Dinerstein, E. D. Wikramanayke, N. D. Burgess, G. V. N. Powell, E. C. Underwood, J. A. D’Amico, et al. 2001. Terrestrial ecoregions of the world: a new map of life on Earth. BioScience 51:933–938.']
  • ['Olson, J. S. 1994. Global ecosystem framework: definitions. USGS EROS Data Center Internal Report. US Geological Survey, Sioux Falls, SD.']
  • ['Pianka, E. R. 2000, Evolutionary Ecology. Benjamin Cummings, San Francisco.']
  • ['Plotkin, J. B., M. D. Potts, N. Leslie, N. Manokaran, J. LaFrankie, and P. S. Ashton. 2000. Species‐area curves, spatial aggregation, and habitat specialization in tropical forests. Journal of Theoretical Biology 207:81–99.']
  • ['Preston, F. W. 1962. The canonical distribution of commonness and rarity. Ecology 43:185–215.']
  • ['Qian, H., and R. E. Ricklefs. 2008. Global concordance in diversity patterns of vascular plants and terrestrial vertebrates. Ecology Letters 11:547–553.']
  • ['Qian, H., J. D. Fridley, and M. W. Palmer. 2007. The latitudinal gradient of species‐area relationships for vascular plants of North America. American Naturalist 170:690–701.']
  • ['Ricklefs, R. E., H. Qian, and P. S. White. 2004. The region effect on mesoscale plant species richness between eastern Asia and eastern North America. Ecography 27:129–136.']
  • ['Rodríguez, P., and H. T. Arita. 2004. Beta diversity and latitude in North American mammals: testing the hypothesis of covariation. Ecography 27:547–556.']
  • ['Rosenzweig, M. L. 1995. Species diversity in space and time. Cambridge University Press, Cambridge.']
  • ['Sitch, S., B. Smith, I. C. Prentice, A. Arneth, A. Bondeau, W. Cramer, J. O. Kaplan, et al. 2003. Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model. Global Change Biology 9:161–185.']
  • ['Šizling, A. L., and D. Storch. 2004. Power‐law species‐area relationships and self‐similar species distributions within finite areas. Ecology Letters 7:60–68.']
  • ['Srivastava, D. S., and J. H. Lawton. 1998. Why more productive sites have more species: an experimental test of theory using tree‐hole communities. American Naturalist 152:510–529.']
  • ['Stephens, P. A., W. J. Sutherland, and R. P. Freckleton. 1999. What is the Allee effect? Oikos 87:185–190.']
  • ['Storch, D., K. L. Evans, and K. J. Gaston. 2005. The species‐area‐energy relationship. Ecology Letters 8:487–492.']
  • ['Storch, D., A. L. Šizling, and K. J. Gaston. 2007. Scaling species richness and distribution: uniting the species‐area and species‐energy relationships. Pages 300–321 in D. Storch, P. A. Marquet, and J. H. Brown, eds. Scaling biodiversity. Cambridge University Press, Cambridge.']
  • ['Storch, D., A. L. Šizling, J. Reif, J. Polechová, E. Šizlingova, and K. J. Gaston. 2008. The quest for a null model for macroecological patterns: geometry of species distributions at multiple spatial scales. Ecology Letters 11:771–784.']
  • ['Tjørve, E., and K. M. C. Tjørve. 2008. The species‐area relationship, self‐similarity, and the true meaning of the z‐value. Ecology 89:3528–3533.']
  • ['Triantis, K. A., M. Mylonas, K. Lika, and K. Vardinoyannis. 2003. A model for the species‐area‐habitat relationship. Journal of Biogeography 30:19–27.']
  • ['Triantis, K. A., M. Mylonas, M. D. Weiser, K. Lika, and K. Vardinoyannis. 2005. Species richness, environmental heterogeneity and area: a case study based on land snails in Skyros archipelago (Aegean Sea, Greece). Journal of Biogeography 32:1727–1735.']
  • ['USGS. 1996. GTOPO30.']
  • ['———. 2002. Global land cover characteristics data base 2.0. US Geologic Survey Earth Resources Observation and Science Center, Sioux Falls, SD.']
  • ['Whittaker, R. J., D. Nogues‐Bravo, and M. B. Araujo. 2007. Geographical gradients of species richness: a test of the water‐energy conjecture of Hawkins et al. (2003) using European data for five taxa. Global Ecology and Biogeography 16:76–89.']
  • ['Williams, C. B. 1964. Patterns in the balance of nature. Academic Press, London.']
  • ['Willig, M. R., and S. K. Lyons. 1998. An analytical model of latitudinal gradients of species richness with an empirical test for marsupials and bats in the New World. Oikos 81:93–98.']
  • ['Willson, M. F. 1974. Avian community organization and habitat structure. Ecology 55:1017–1029.']
  • ['Wright, D. H. 1983. Species‐energy theory: an extension of species‐area theory. Oikos 41:496–506.']
  • ['Wylie, J. L., and D. J. Currie. 1993. Species‐energy theory and patterns of species richness. I. Patterns of bird, angiosperm, and mammal species richness on islands. Biological Conservation 63:137–144.']