Bradford A. Hawkins

Bradford A. Hawkins is a Professor of ecology in the Department of Ecology and Evolutionary Biology, University of California, Irvine. His primary research question is why do diversity gradients exist? Answering this question requires the integration of a wide range of disciplines. One thing that is clear is that scale matters; explanations for diversity gradients at one scale cannot be applied to other scales. At the moment, his major focus is on larger scales, ranging from subcontinental to global patterns. Here the single most important problem is working out how effects operating in ecological time and effects operating in evolutionary time are linked. He and collaborators are pursuing this link by focusing on the relationship between current climate and historical patterns of climate change. Given that we are moving into a period of rapid global climate change, it is critical that we understand what aspects of climate drive diversity, and how organisms will respond when these variables change in time. In fact, we already have a descriptive answer to this question, at least at the global scale. Sorting out the mechanism(s) underlying the empirical relationships between diversity and climate, on the other hand, is more of a challenge; and an emphasis of his research is to identify the most likely mechanisms that explain how climate operates on diversity both now and in the past. This requires information about both contemporary and paleoclimates. It has also become clear that a complete understanding of diversity gradients requires explicit evolutionary data, so another component of his research program is incorporating phylogenetic data into analyses of species richness. He also maintains an interest in other macroecological patterns (e.g., body size and range size gradients).

Biography Updated on 30 May 2007

Articles in Scholarly Journals [Incomplete List]

  1. Macroevolutionary dynamics in environmental space and the latitudinal diversity gradient in New World birds
    Proceedings of the Royal Society B: Biological Sciences, vol. 274, no. 1606, pp. 43–52, 2007
  2. Contemporary richness of holarctic trees and the historical pattern of glacial retreat
    Ecography, vol. 30, no. 2, pp. 173–182, 2007
  3. Seeing the forest for the trees: partitioning ecological and phylogenetic components of Bergmann's rule in European Carnivora
    Ecography, vol. 30, no. 4, pp. 598–608, 2007
  4. Red herrings revisited: spatial autocorrelation and parameter estimation in geographical ecology
    Ecography, vol. 30, no. 3, pp. 375–384, 2007
  5. GLOBAL MODELS FOR PREDICTING WOODY PLANT RICHNESS FROM CLIMATE: COMMENT
    Ecology, vol. 88, no. 1, p. 255, 2007
  6. Broad-scale patterns of body size in squamate reptiles of Europe and North America
    Journal of Biogeography, vol. 33, no. 5, pp. 781–793, 2006
  7. Post-Eocene climate change, niche conservatism, and the latitudinal diversity gradient of New World birds
    Journal of Biogeography, vol. 33, no. 5, pp. 770–780, 2006
  8. The geographic distribution of mammal body size in Europe
    Global Ecology and Biogeography, vol. 15, no. 2, pp. 173–181, 2006
  9. Mapping macroecology
    Global Ecology and Biogeography, vol. 15, no. 5, pp. 433–437, 2006
  10. Beyond Rapoport's rule: evaluating range size patterns of New World birds in a two-dimensional framework
    Global Ecology and Biogeography, vol. 15, no. 5, pp. 461–469, 2006
  11. Conserving parasitoid assemblages of North American pest Lepidoptera: Does biological control by native parasitoids depend on landscape complexity?
    Biological Control, vol. 37, no. 2, pp. 173–185, 2006
  12. Energy, water and large-scale patterns of reptile and amphibian species richness in Europe
    Acta Oecologica, vol. 28, no. 1, pp. 65–70, 2005
  13. Using lower trophic level factors to predict outcomes in classical biological control of insect pests
    Basic and Applied Ecology, vol. 6, no. 6, pp. 571–584, 2005
  14. Latitudinal Gradients1
    Ecology, vol. 86, no. 9, p. 2261, 2005
  15. Water links the historical and contemporary components of the Australian bird diversity gradient
    Journal of Biogeography, vol. 32, no. 6, pp. 1035–1042, 2005
  16. Macroecological explanations for differences in species richness gradients: a canonical analysis of South American birds
    Journal of Biogeography, vol. 31, no. 11, pp. 1819–1827, 2004
  17. Does plant richness influence animal richness?: the mammals of Catalonia (NE Spain)
    Diversity Distributions, vol. 10, no. 4, pp. 247–252, 2004
  18. Predictions and tests of climate-based hypotheses of broad-scale variation in taxonomic richness
    Ecology Letters, vol. 7, no. 12, pp. 1121–1134, 2004
  19. Summer vegetation, deglaciation and the anomalous bird diversity gradient in eastern North America
    Global Ecology and Biogeography, vol. 13, no. 4, pp. 321–325, 2004
  20. A test of multiple hypotheses for the species richness gradient of South American owls
    Oecologia, vol. 140, no. 4, 2004
  21. 'Latitude' and geographic patterns in species richness
    Ecography, vol. 27, no. 2, pp. 268–272, 2004
  22. Bergmann's rule and the mammal fauna of northern North America
    Ecography, vol. 27, no. 6, pp. 715–724, 2004
  23. Invited Views in Basic and Applied Ecology: Are we making progress toward understanding the global diversity gradient?
    Basic and Applied Ecology, vol. 5, no. 1, pp. 1–3, 2004
  24. Relative influences of current and historical factors on mammal and bird diversity patterns in deglaciated North America
    Global Ecology and Biogeography, vol. 12, no. 6, pp. 475–481, 2003
  25. Spatial autocorrelation and red herrings in geographical ecology
    Global Ecology and Biogeography, vol. 12, no. 1, pp. 53–64, 2003
  26. Water-energy balance and the geographic pattern of species richness of western Palearctic butterflies
    Ecological Entomology, vol. 28, no. 6, pp. 678–686, 2003
  27. Does Herbivore Diversity Depend on Plant Diversity? The Case of California Butterflies
    The American Naturalist, vol. 161, no. 1, pp. 40–49, 2003
  28. Table A2: Chemicals used in the analysis
    The American Naturalist, vol. 161, no. 4, pp. 507–522, 2003
  29. The influence of varying spatial heterogeneity on the refuge model for coexistence of specialist parasitoid assemblages
    Oikos, vol. 100, no. 2, pp. 241–250, 2003
  30. Coexistence of specialist parasitoids with host refuges in the laboratory and the dynamics of spatial heterogeneity in attack rate
    Oikos, vol. 100, no. 2, pp. 232–240, 2003
  31. Erratum
    Oikos, vol. 100, no. 3, pp. 636–636, 2003
  32. Food web complexity and higher-level ecosystem services
    Ecology Letters, vol. 6, no. 7, pp. 587–593, 2003
  33. ENERGY, WATER, AND BROAD-SCALE GEOGRAPHIC PATTERNS OF SPECIES RICHNESS
    Ecology, vol. 84, no. 12, p. 3105, 2003
  34. PRODUCTIVITY AND HISTORY AS PREDICTORS OF THE LATITUDINAL DIVERSITY GRADIENT OF TERRESTRIAL BIRDS
    Ecology, vol. 84, no. 6, p. 1608, 2003
  35. The mid-domain effect cannot explain the diversity gradient of Nearctic birds
    Global Ecology and Biogeography, vol. 11, no. 5, pp. 419–426, 2002
  36. Population regulation, emergent properties, and a requiem for density dependence
    Oikos, vol. 99, no. 3, pp. 600–606, 2002
  37. Ecology's oldest pattern?
    Endeavour, vol. 25, no. 3, p. 133, 2001
  38. Area and the latitudinal diversity gradient for terrestrial birds
    Ecology Letters, vol. 4, no. 6, pp. 595–601, 2001
  39. Top-down and bottom-up forcesin the population and community ecology of insects
    Basic and Applied Ecology, vol. 2, no. 4, pp. 293–294, 2001
  40. Latitudinal Gradients in Colony Size for Social Insects: Termites and Ants Show Different Patterns
    The American Naturalist, vol. 157, no. 1, pp. 97–106, 2001
  41. Site-Dependent Regulation of Population Size: Comment
    Ecology, vol. 81, no. 4, p. 1166, 2000
  42. Galls as habitats: the inquiline communities of insect galls
    Basic and Applied Ecology, vol. 1, no. 1, pp. 3–11, 2000
  43. Diversity, function and stability in parasitoid communities
    Ecology Letters, vol. 3, no. 1, pp. 35–40, 2000
  44. Nature, vol. 400, no. 6744, pp. 498–498, 1999
  45. Is the Biological Control of Insects a Natural Phenomenon?
    Oikos, vol. 86, no. 3, p. 493, 1999
  46. Effects of Sampling Effort on Characterization of Food-Web Structure
    Ecology, vol. 80, no. 3, p. 1044, 1999
  47. CRITICAL APPRAISAL Critical appraisals allow the analytical review of existing knowledge on current topics of significance in ecological entomology. They should assess the worth or quality of the work in the field and suggest areas for investigation. Towards an empirically-based theory of herbivore demography
    Ecological Entomology, vol. 23, no. 3, pp. 340–349, 1998
  48. Patterns of diversity for aphidiine (Hymenoptera: Braconidae) parasitoid assemblages on aphids (Homoptera)
    Oecologia, vol. 116, no. 1-2, pp. 234–242, 1998
  49. Transcontinental Crashes of Insect Populations?
    American Naturalist, vol. 152, no. 3, p. 480, 1998
  50. Source food webs as estimators of community web structure
    Acta Oecologica, vol. 18, no. 5, pp. 575–586, 1997
  51. The colonization of native phytophagous insects in North America by exotic parasitoids
    Oecologia, vol. 112, no. 4, pp. 566–571, 1997
  52. Predators, Parasitoids, and Pathogens as Mortality Agents in Phytophagous Insect Populations
    Ecology, vol. 78, no. 7, p. 2145, 1997
  53. Variability in Parasitoid Community Structure
    The Journal of Animal Ecology, vol. 65, no. 4, p. 501, 1996
  54. Structure of the Parasitoid Communities of Grass-Feeding Chalcid Wasps
    The Journal of Animal Ecology, vol. 64, no. 6, p. 708, 1995
  55. Survival Patterns and Mortality Sources of Herbivorous Insects: Some Demographic Trends
    American Naturalist, vol. 145, no. 4, p. 563, 1995
  56. Minimal Community Structure: How Parasitoids Divide Resources
    Ecology, vol. 75, no. 1, p. 79, 1994
  57. Parasitoid Species Richness, Host Mortality, and Biological Control
    American Naturalist, vol. 141, no. 4, p. 634, 1993
  58. Accumulation of Native Parasitoid Species on Introduced Herbivores: A Comparison of Hosts as Natives and Hosts as Invaders
    American Naturalist, vol. 141, no. 6, p. 847, 1993
  59. Predicting Parasitoid Species Richness
    American Naturalist, vol. 142, no. 4, p. 671, 1993
  60. African Fig Wasp Communities: Undersaturation and Latitudinal Gradients in Species Richness
    The Journal of Animal Ecology, vol. 61, no. 2, p. 361, 1992
  61. Global Patterns of Parasitoid Assemblage Size
    The Journal of Animal Ecology, vol. 59, no. 1, p. 57, 1990
  62. Species Diversity in the Third and Fourth Trophic Levels: Patterns and Mechanisms
    The Journal of Animal Ecology, vol. 57, no. 1, p. 137, 1988
  63. Species richness for parasitoids of British phytophagous insects
    Nature, vol. 326, no. 6115, Article ID 326788a0, 2 pages, 1987
  64. Precise Sex Ratios in Highly Inbred Parasitic Wasps
    American Naturalist, vol. 120, no. 5, p. 653, 1982