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Philip S. Ward

Research interests

In many terrestrial habitats – especially those of the lowland tropics – ants rival other arthropods in numerical abundance, ecological importance and species richness. My research is concerned with unraveling details about the evolutionary history of ants and attempting to understand the processes that have generated such an extraordinary diversity of form and function. This work entails both species-level taxonomy and analyses of phylogenetic relationships. Components of this research include:

  1. determining the limits of intra- and interspecific variation,
  2. providing pragmatic tools for the identification of species,
  3. inferring phylogenetic relationships among recognized taxa, and
  4. using the phylogeny as a framework for analyzing the evolution of biological features of interest.

The Ant AToL Project, carried out in collaboration with colleagues Brian Fisher (California Academy of Sciences) and Seán Brady and Ted Schultz (Smithsonian Institution), has focused on recovering the phylogeny, biogeography and divergence dates of the major lineages of ants. We are employing about 14 nuclear genes, many developed for use in ant phylogenetics for the first time, and data are analyzed using model-based approaches (maximum likelihood and Bayesian methods). In addition to probing the “deep history” of the major ant clades (Brady et al., 2006), we have also been investigating phylogenetic relationships within several large subgroups of ants. We recently completed a study of the ant subfamily Dolichoderinae (Ward et al., 2010), which demonstrated that diversification of crown-group dolichoderines postdates the K/T boundary and occurred later in Australia than other parts of the world. This study also revealed the striking sensitivity of phylogenetic estimates to data partitioning, outgroup composition and base frequency heterogeneity. Current work is focused on the evolutionary history of dorylomorphs and myrmicines, and a reevaluation of relationships among early branching lineages of poneroids and leptanillines.

A focal group for systematic studies in the last 20 years has been the ant subfamily Pseudomyrmecinae, a tropicopolitan clade of mostly arboreal (twig-dwelling) ants that includes a significant minority of ant-plant mutualists (Ward, 1991). A phylogenetic study (Ward & Downie, 2005), drawing on both morphological and DNA sequence data, confirmed most relationships suggested earlier on the basis of morphology alone (Ward, 1989, 1990, 1993, 1999b, 2001), but also indicated that the Paleotropical genus Tetraponera is paraphyletic (and source of the more diverse New World clade Pseudomyrmex). Stem-group pseudomyrmecines are inferred to have arisen in the late Cretaceous, with their sister group being the subfamily Myrmeciinae. Recent taxonomic work has focused on the species-level taxonomy of Afrotropical Tetraponera (Ward, 2006, 2009).

Other research includes faunistic and taxonomic studies on the myrmecofauna of California and Baja California (Johnson & Ward, 2002; Boulton & Ward, 2002; Ward, 2005a; see also the “ants of California” page on AntWeb); investigations of relationships among myrmeciine and dorylomorph ants (Ward & Brady, 2003, 2009; Brady & Ward, 2005); and analyses of leaf litter ant communities (Ward, 2000). The current state of ant systematics and the incorporation of molecular phylogenetic results into ant taxonomy were discussed in Ward (2007, 2009, 2011). A previously published bibliography of ant systematics (Ward et al., 1996) has been updated, and is now available online at the AntCat site.

Publications

  1. Ward, P. S., Hebert, P., Harmsen, R. 1973. A note on the distribution of Oeneis chryxus strigulosa (Lepidoptera: Satyridae). Canadian Entomologist 105:1373-1374.
  2. Harmsen, R., Hebert, P., Ward, P. S. 1974. On the origin of austral elements in the moth fauna of south-eastern Ontario, including a number of species new for Canada. Journal of Research on Lepidoptera 12:127-134.
  3. Ward, P. S., Harmsen, R., Hebert, P. 1974. An annotated checklist of the macroheterocera of south-eastern Ontario. Journal of Research on Lepidoptera 13:23-42.
  4. Hebert, P., Ward, P. S., Harmsen, R. 1974. Diffuse competition in Lepidoptera. Nature 252:389-391.
  5. Hebert, P., Ward, P. S., Harmsen, R. 1975. Competition and species abundance – Reply. Nature 257:160-161.
  6. Ward, P. S. 1976. Probing ponerine ants. Australian Natural History l8:384-387.
  7. Ward, P. S. 1980. A systematic revision of the Rhytidoponera impressa group (Hymenoptera: Formicidae) in Australia and New Guinea. Australian Journal of Zoology 28:475-498. [Pdf file]
  8. Ward, P. S. 1980. Genetic variation and population differentiation in the Rhytidoponera impressa group, a species complex of ponerine ants (Hymenoptera: Formicidae). Evolution 34:1060-1076. [Pdf file]
  9. Ward, P. S., Taylor, R. W. 1981. Allozyme variation, colony structure, and genetic relatedness in the primitive ant Nothomyrmecia macrops Clark (Hymenoptera: Formicidae). Journal of the Australian Entomological Society 20:177-183.
  10. Ward, P. S. 1981. Ecology and life history of the Rhytidoponera impressa group (Hymenoptera: Formicidae). I. Habitats, nest sites, and foraging behavior. Psyche 88:89-108. [Pdf file]
  11. Ward, P. S. 1981. Ecology and life history of the Rhytidoponera impressa group (Hymenoptera: Formicidae). II. Colony origin, seasonal cycles, and reproduction. Psyche 88:109-126. [Pdf file]
  12. Ward, P. S., Boussy, I. A., Swincer, D. E. 1982. Electrophoretic detection of enzyme polymorphism and differentiation in three species of spider mites (Tetranychus) (Acari: Tetranychidae). Annals of the Entomological Society of America 75:595-598.
  13. Ward, P. S. 1983. Genetic relatedness and colony organization in a species complex of ponerine ants. I. Genotypic and phenotypic composition of colonies. Behavioral Ecology and Sociobiology 12:285-299.
  14. Ward, P. S. 1983. Genetic relatedness and colony organization in a species complex of ponerine ants. II. Patterns of sex ratio investment. Behavioral Ecology and Sociobiology 12:301-307.
  15. Ward, P. S. 1984. A revision of the ant genus Rhytidoponera (Hymenoptera: Formicidae) in New Caledonia. Australian Journal of Zoology 32:131-175. [Pdf file]
  16. Ward, P. S. 1985. The Nearctic species of the genus Pseudomyrmex (Hymenoptera: Formicidae). Quaestiones Entomologicae 21:209-246. [Pdf file]
  17. Ward, P. S. 1985. Taxonomic congruence and disparity in an insular ant fauna: Rhytidoponera in New Caledonia. Systematic Zoology 34:140-151. [Pdf file]
  18. Tibayrenc, M., P. Ward, A. Moya and F. Ayala. 1986. Natural populations of Trypanosoma cruzi, the agent of Chagas’ disease, have a complex multiclonal structure. Proceedings of the National Academy of Sciences U. S. A. 83:115-119.
  19. Ward, P. S. 1986. Functional queens in the Australian greenhead ant, Rhytidoponera metallica (Hymenoptera: Formicidae). Psyche 93:1-12. [Pdf file]
  20. Ward, P. S. 1987. Distribution of the introduced Argentine ant (Iridomyrmex humilis) in natural habitats of the lower Sacramento Valley, and its effects on the indigenous ant fauna. Hilgardia 55(2):1-16. [Pdf file]
  21. Ward, P. S. 1988. Mesic elements in the western Nearctic ant fauna: taxonomic and biological notes on Amblyopone, Proceratium, and Smithistruma (Hymenoptera: Formicidae). Journal of the Kansas Entomological Society 61:102-124. [Pdf file]
  22. Ward, P. S. 1989. Genetic and social changes associated with ant speciation. In Breed, M. D. & R. E. Page (Eds.). The genetics of social evolution. Boulder, Colorado: Westview Press, pp. 123-148.
  23. Ward, P.S. 1989. Systematic studies on pseudomyrmecine ants: revision of the Pseudomyrmex oculatus and P. subtilissimus species groups, with taxonomic comments on other species. Quaestiones Entomologicae 25:393-468. [Pdf file]
  24. Ward, P.S. 1990. The ant subfamily Pseudomyrmecinae (Hymenoptera: Formicidae): generic revision and relationship to other formicids. Systematic Entomology 15:449-489. [Pdf file]
  25. Ward, P.S. 1991. Phylogenetic analysis of pseudomyrmecine ants associated with domatia-bearing plants. In Cutler, D.F. & C.R. Huxley (Eds.) Ant/plant interactions. Oxford: Oxford Univ. Press, pp. 335-352.
  26. Frumhoff, P.C., Ward, P.S. 1992. Individual-level selection, colony-level selection, and the association between polygyny and worker monomorphism in ants. American Naturalist 139:559-590.
  27. Baroni Urbani, C., Bolton, B., Ward, P.S. 1992. The internal phylogeny of ants (Hymenoptera: Formicidae). Systematic Entomology 17:301-329.
  28. Ward, P.S. 1992. Ants of the genus Pseudomyrmex (Hymenoptera: Formicidae) from Dominican amber, with a synopsis of the extant Antillean species. Psyche 99:55-85. [Pdf file]
  29. Gullan, P. J., Buckley, R. C., Ward, P. S. 1993. Ant-tended scale insects (Hemiptera: Coccidae: Myzolecanium) within lowland rainforest trees in Papua New Guinea. Journal of Tropical Ecology 9:81-91. [Pdf file]
  30. Ward, P. S. 1993. Systematic studies on Pseudomyrmex acacia-ants (Hymenoptera: Formicidae: Pseudomyrmecinae). Journal of Hymenoptera Research 2:117-168. [Pdf file]
  31. Ward, P. S. 1994. Adetomyrma, an enigmatic new ant genus from Madagascar (Hymenoptera: Formicidae), and its implications for ant phylogeny. Systematic Entomology 19:159-175.
  32. Rejmánek, M., Ward, P. S., Webster, G. L., Randall, J. M. 1994. Systematics and biodiversity. [Correspondence.] Trends in Ecology and Evolution 9:228-229.
  33. Olson, D. M., Ward, P. S. 1996. The ant fauna (Hymenoptera: Formicidae) of Kirindy Forest (tropical dry forest) in western Madagascar. Pp. 161-164 in Ganzhorn, J. U., Sorg, J.-P. (eds.). Ecology and economy of a tropical dry forest in Madagascar. Primate Report 46-1. Göttingen: German Primate Center (DPZ), 382 pp.
  34. Ward, P. S., Bolton, B. B., Shattuck, S. O., Brown, W. L., Jr. 1996. A bibliography of ant systematics. University of California Publications in Entomology 116:1-417.
  35. Ward, P. S. 1996. A new workerless social parasite in the ant genus Pseudomyrmex (Hymenoptera: Formicidae), with a discussion of the origin of social parasitism in ants. Systematic Entomology 21:253-263. [Pdf file]
  36. Ward, P. S. 1997. Ant soldiers are not modified queens. Nature 385:494-495.
  37. Ward, P. S. 1999a. Deceptive similarity in army ants of the genus Neivamyrmex (Hymenoptera: Formicidae): taxonomy, distribution and biology of N. californicus (Mayr) and N. nigrescens (Cresson). Journal of Hymenoptera Research 8:74-97.
  38. Gadau, J., Brady, S. G., Ward, P. S. 1999. Systematics, distribution, and ecology of an endemic California Camponotus quercicola (Hymenoptera: Formicidae). Annals of the Entomological Society of America 92:514-522.
  39. Ward, P. S. 1999b. Systematics, biogeography and host plant associations of the Pseudomyrmex viduus group (Hymenoptera: Formicidae), Triplaris- and Tachigali-inhabiting ants. Zoological Journal of the Linnean Society 126:451-540. [Pdf file]
  40. Wetterer, J. K., Ward, P. S., Wetterer, A. L., Longino, J. T., Trager, J. C., Miller, S. E. 2000. Ants (Hymenoptera: Formicidae) of Santa Cruz Island, California. Bulletin. Southern California Academy of Sciences 99:25-31.
  41. Ward, P. S. 2000. On the identity of Pheidole vaslitii Pergande (Hymenoptera: Formicidae), a neglected ant from Baja California. Journal of Hymenoptera Research 9:85-98. [Pdf file]
  42. Ward, P. S. 2000. Broad-scale patterns of diversity in leaf litter ant communities. Pp. 99-121 in: Agosti, D., Majer, J. D., Alonso, L. E., Schultz, T. R. (eds.) Ants. Standard methods for measuring and monitoring biodiversity. Washington: Smithsonian Institution Press, xix + 280 pp.
  43. Brady, S. G., Gadau, J., Ward, P. S. 2000. Systematics of the ant genus Camponotus (Hymenoptera: Formicidae): a preliminary analysis using data from the mitochondrial gene cytochrome oxidase I. Pp. 131-139 in: Austin, A. D., Dowton, M. (eds.) Hymenoptera. Evolution, biodiversity and biological control. Collingwood, Victoria: CSIRO Publishing, xi + 468 pp.
  44. Ward, P. S. 2001. Taxonomy, phylogeny and biogeography of the ant genus Tetraponera (Hymenoptera: Formicidae) in the Oriental and Australian regions. Invertebrate Taxonomy 15:589-665. [Pdf file]
  45. Gronlund, C. J., Deangelis, M. D., Pruett-Jones, S., Ward, P. S., Coyne, J. A. 2002. Mate grasping in Drosophila pegasa.  Behaviour 139:545-572.
  46. Johnson, R. A., Ward, P. S. 2002.  Biogeography and endemism of ants (Hymenoptera: Formicidae) in Baja California, Mexico: a first overview.  Journal of Biogeography 29:1009-1026. [Pdf file]
  47. Boulton, A. M., Ward, P. S. 2002.  Ants.  Pp. 112-128 in Case, T. J., Cody, M. L. & Ezcurra, E. (eds.) A new island biogeography of the Sea of Cortés. Oxford: Oxford University Press, xvii + 669 pp
  48. Ward, P. S., Boulton, A. M. 2002.  Checklist of the ants of the Gulf of California islands.  Pp. 545-553 in Case, T. J., Cody, M. L. & Ezcurra, E. (eds.) A new island biogeography of the Sea of Cortés. Oxford: Oxford University Press, xvii + 669 pp.
  49. Ward, P. S., Brady, S. G.  2003.  Phylogeny and biogeography of the ant subfamily Myrmeciinae (Hymenoptera: Formicidae).  Invertebrate Systematics 17:361-386. [Pdf file]
  50. Ward, P. S.  2003.  Subfamilia Pseudomyrmecinae.  Pp. 331-333 in Fernández, F. (ed.) Introducción a las hormigas de la región Neotropical. Bogotá, Colombia: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xxvi + 398 pp. [Pdf file]
  51. Kaspari, M., Ward, P. S., Yuan, M. 2004. Energy gradients and the geographic distribution of local ant diversity. Oecologia 140:407-413. [Pdf file]
  52. Ward, P. S., Downie, D. A.  2005.  The ant subfamily Pseudomyrmecinae (Hymenoptera: Formicidae): phylogeny and evolution of big-eyed arboreal ants. Systematic Entomology 30:310-335. [Pdf file]
  53. Ward, P. S.  2005.  A synoptic review of the ants of California (Hymenoptera: Formicidae).  Zootaxa 936:1-68. [Pdf file]
  54. Ward, P. S., Brady, S. G.; Fisher, B. L.; Schultz, T. R. 2005. Assembling the ant “Tree of Life” (Hymenoptera: Formicidae). Myrmecologische Nachrichten 7:87-90. [Pdf file]
  55. Boulton, A. M., Davies, K. F., Ward, P. S. 2005. Species richness, abundance, and composition of ground-dwelling ants in northern California grasslands: role of plants, soil, and grazing. Environmental Entomology 34:96-104. [Pdf file]
  56. Brady, S. G., Ward, P. S. 2005. Morphological phylogeny of army ants and other dorylomorphs (Hymenoptera: Formicidae). Systematic Entomology 30:593-618. [Pdf file]
  57. van der Hammen, T.; Ward, P. S. 2005. Ants from the Ecoandes expeditions: diversity and distribution. Studies on Tropical Andean Ecosystems 6:239-248. [Pdf file]
  58. Suarez, A. V., Holway, D. A., Ward, P. S. 2005. The role of opportunity in the unintentional introduction of nonnative ants. Proceedings of the National Academy of Sciences of the United States of America 102:17032-17035. [Pdf file]
  59. Ward, P. S. 2006. The ant genus Tetraponera in the Afrotropical region: synopsis of species groups and revision of the T. ambigua-group (Hymenoptera: Formicidae). Myrmecologische Nachrichten 8:119-130. [Pdf file]
  60. Ward, P. S.  2006.  Ants.  Current Biology 16:152-155. [Pdf file]
  61. Brady, S. G., Schultz, T. R., Fisher, B. L., Ward, P. S. 2006. Evaluating alternative hypotheses for the early evolution and diversification of ants. Proceedings of the National Academy of Sciences of the United States of America 103:18172-18177. [Pdf file]
  62. Bolton, B., Alpert, G., Ward, P. S., Naskrecki, P. 2007. Bolton’s Catalogue of ants of the world: 1758-2005. Cambridge, Mass.: Harvard University Press, CD-ROM.
  63. Ward, P. S. 2007. Edward O. Wilson and his contributions to ant systematics. Memoirs of the American Entomological Institute 80:3-7. [Pdf file]
  64. Ward, P. S. 2007. The ant genus Leptanilloides: discovery of the male and evaluation of phylogenetic relationships based on DNA sequence data. Memoirs of the American Entomological Institute 80:637-649. [Pdf file]
  65. Ward, P. S. 2007. Phylogeny, classification, and species-level taxonomy of ants (Hymenoptera: Formicidae). Zootaxa 1668:549-563. [Pdf file]
  66. Ward, P. S., Brady, S. G. 2009. Rediscovery of the ant genus Amyrmex Kusnezov (Hymenoptera: Formicidae) and its transfer from Dolichoderinae to Leptanilloidinae. Zootaxa 2063:46-54. [Pdf file]
  67. Kautz, S., Lumbsch, H. T., Ward, P. S., Heil, M. 2009. How to prevent cheating: a digestive specialization ties mutualistic plant-ants to their ant-plant partners. Evolution 63:839-853. [Pdf file]
  68. Wernegreen, J. J., Kauppinen, S. N., Brady, S. G., Ward, P. S. 2009. One nutritional symbiosis begat another: phylogenetic evidence that the ant tribe Camponotini acquired Blochmannia by tending sap-feeding insects. BMC Evolutionary Biology (doi:10.1186/1471-2148-9-292) 9:Article 292. [Pdf file]
  69. Ward, P. S. 2009. The ant genus Tetraponera in the Afrotropical region: the T. grandidieri group (Hymenoptera: Formicidae). Journal of Hymenoptera Research 18:285-304. [Pdf file]
  70. Ward, P. S. 2009. Taxonomy, phylogenetics, and evolution. Pp. 3-17 in: Lach, L., Parr, C. L., Abbott, K. (eds) 2009. Ant ecology. Oxford: Oxford University Press, xvii + 410 pp. [Pdf file]
  71. Ward, P. S., Brady, S. G., Fisher, B. L., Schultz, T. R. 2010. Phylogeny and biogeography of dolichoderine ants: effects of data partitioning and relict taxa on historical inference. Systematic Biology 59:342-362. [Pdf file]
  72. Lucky, A., Ward, P. S. 2010. Taxonomic revision of the ant genus Leptomyrmex Mayr (Hymenoptera: Formicidae). Zootaxa 2688:1-67. [Pdf file]
  73. Ward, P. S. 2011. Integrating molecular phylogenetic results into ant taxonomy (Hymenoptera: Formicidae). Myrmecological News 15:21-29. [Pdf file]
  74. Roura-Pascual, N., Hui, C., Ikeda, T., Leday, G., Richardson, D. M., Carpintero, S., Espadaler, X., Gómez, C., Guénard, B., Hartley, S., Krushelnycky, P., Lester, P. J., McGeoch, M. A., Menke, S. B., Pedersen, J. S., Pitt, J. P. W., Reyes, J., Sanders, N. J., Suarez, A. V., Touyama, Y., Ward, D., Ward, P. S., Worner, S. P. 2011. The relative roles of climatic suitability and anthropogenic influence in determining the pattern of spread in a global invader. Proceedings of the National Academy of Sciences U. S. A. 108:220-225. [Pdf file]
  75. Ward, P. S., Sumnicht, T. P. 2012. Molecular and morphological evidence for three sympatric species of Leptanilla (Hymenoptera: Formicidae) on the Greek island of Rhodes. Myrmecological News, in press.

Abstracts, Reviews

  • Ward, P. S. 1982. Colony structure and genetic relatedness in a species complex of ponerine ants. In Breed, M. D., Michener, C. D., Evans, H. E. (eds.) The biology of social insects; proceedings of the Ninth Congress IUSSI. Boulder: Westview Press, pp. 413-414 [Abstract].
  • Ward, P. S. 1983. Sex-ratio interactions between queenright and queenless colonies in rainforest ants of the Rhytidoponera impressa group. In Proceedings 18th Intern. Ethol. Conference, Brisbane, Qld., p. 299 [Abstract].
  • Ward, P. S. 1985. Review of: Wehner, R. et al. Foraging strategies in individually searching ants, Cataglyphis bicolor. Animal Behaviour 33:336-337.
  • Ward, P. S. 1995. Ants on the run. [Review of Gotwald, W. H., Jr. 1995. Army ants. The biology of social predation. Ithaca, New York: Cornell University Press, xviii + 302 pp.] Science 270:319-320.
  • Ward, P. S. 1998. Phylogeny and biogeography of host plant associations in Neotropical pseudomyrmecine ants (Hymenoptera: Formicidae). P. 499 in: Schwarz, M. P., Hogendoorn, K. (eds.) Social insects at the turn of the millenium. Proceedings of the XIII International Congress of IUSSI. Adelaide, Australia. 29 December 1998 – 3 January 1999. Adelaide: XIII Congress of IUSSI, 535 pp. [Abstract].
  • Brady, S. G., Gadau, J., Ward, P. S. 1999. Is the ant genus Camponotus paraphyletic? Pp. 27-28 in: 4th International Hymenopterists Conference, 6-11th January 1999, Canberra, Australia. Program and abstracts. Glen Osmond, South Australia: 4th International Hymenopterists Conference, 96 pp. [Abstract].
  • Ward, P. S.; Brady, S. G.  2002.  Phylogeny and biogeography of the ant genera Myrmecia and Nothomyrmecia (Hymenoptera: Formicidae) and related fossil taxa.  P. 156 in: XIV International Congress of IUSSI. The Golden Jubilee Proceedings. 27 July – 3 August 2002, Hokkaido University, Sapporo, Japan.  Sapporo: XIV International Congress of IUSSI, 233 pp. [Abstract.].

Limited Distribution

  • Sugden, E. A., Ward, P. S., Shapiro, A. M., Teague, S. 1985. Invertebrates. Pp. 47-62 in: Weathers, W. W., Cole, R. (eds.) Flora and fauna of the Stebbins Cold Canyon Reserve, Solano County, California. Institute of Ecology Publication No. 29. University of California, Davis. vi + 84 pp.
  • Ward, P. S. 1990. The endangered ants of Mauritius: doomed like the dodo? Notes from Underground No. 4 (Spring 1990):3-5.
  • Ward, P. S. 1994. Les fourmis. P. 30 in: Goodman, S. N., Langrand, O. (eds.) Inventaire biologique Forêt de Zombitse. Recherches pour le Développement. Série Sciences Biologiques. No. Spécial. Antananarivo, Madagascar: Centre d’Information et de Documentation Scientifique et Technique, 106 pp.
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