Community Ecology

, Volume 6, Issue 1, pp 101–107 | Cite as

Diffuse competition and continuous niche shifts in size-structured populations of predatory salamanders

  • W. J. ResetaritsJr.Email author
  • J. E. Fauth


Size-specific interactions between predators can affect both species population dynamics and the structure and biodiversity of communities they inhabit. Interactions between size-structured populations of predators, especially those with complex life-cycles, often change with resource-use changes driven by ontogenetic niche shifts. However, if resource use is determined largely by prey size, generalist predators may compete across a wider range of body sizes and life stages resulting in diffuse intra- and interspecific competition. We examined size- and stage-specific interactions between juvenile sirens (Siren i. intermedia) and adult newts (Notophthalmus viridescens dorsalis) in the context of previous experiments demonstrating competitive equality of larvae and strong effects of adult S. intermedia on adult N. viridescens. Competition between juvenile siren and adult newts was mutually negative and roughly symmetrical. Two S. intermedia reduced growth of three N. viridescens by 21%, while three N. viridescens reduced growth of two S. intermedia by 29%. Together with previous work, this implicates diffuse competition as a critical feature in the ecology of these species across the range of body sizes and suggests that intensity of competition varies more with size than species identity. Competition that varies incrementally with body size expands the realm of possibilities for continuous niche changes and diffuse competition across large size gradients. For generalist predators such as S. intermedia and N. viridescens, body size, except at the extremes, is not an adequate niche difference either intra- or interspecifically.


Generalist predators Intraguild predation Notophthalmus Ontogenetic niche Siren Species coexistence Temporary ponds 



Analysis of Variance


Multivariate Analyis of Variance


Snout to posterior margin of vent


Total length


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  1. Abrams, P. A. 1994. Evolutionarily stable growth rates in size-structured populations under size-related competition. Theor. Pop. Biol. 46:78–95.CrossRefGoogle Scholar
  2. Altig, R. 1967. Food of Siren intermedia nettingi in a spring-fed swamp in southern Illinois. Am. Midl. Nat. 77:239–241.CrossRefGoogle Scholar
  3. Brodie, E.D. Jr, J. L. Hensel, Jr. and J. A. Johnson. 1974. Toxicity of the urodele amphibians Taricha, Notophthalmus, Cynops and Paramesotriton (Salamandridae). Copeia 1974:506–511.CrossRefGoogle Scholar
  4. Chalcraft, D. R. and W. J. Resetarits, Jr. 2004. Metabolic rate models and the substitutability of predator populations. J. Anim. Ecol. 73:323–332.CrossRefGoogle Scholar
  5. Claessen, D., A. M. de Roos, and L. Persson. 2000. Dwarfs and giants: Cannibalism and competition in size-structured populations. Am. Nat. 155:219–237.CrossRefPubMedPubMedCentralGoogle Scholar
  6. Collette, B.B. and F. R. Gehlbach. 1961. The salamander Siren intermedia intermedia LeConte in North Carolina. Herpetologica 17:203–204.Google Scholar
  7. Crother, B. I. (ed.). 2000. Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding. SSAR Herpetological Circular 29. iii + 82 pp.Google Scholar
  8. de Roos, A. M. and L. Persson, L. 2001. Physiologically structured models: From versatile technique to ecological theory. Oikos 94:51–71.CrossRefGoogle Scholar
  9. Ebenman, B. 1987. Niche differences between age classes and intraspecific competition in age-structured populations. J. Theor. Biol. 124:25–33.CrossRefGoogle Scholar
  10. Ebenman, B. and L. Persson (eds) 1988. Size-structured Populations: Ecology and Evolution. Springer-Verlag, Berlin, Germany.Google Scholar
  11. Fauth, J. E. and W. J. Resetarits Jr. 1991. Interactions between the salamander Siren intermedia and the keystone predator Notophthalmus viridescens. Ecology 72:827–838.CrossRefGoogle Scholar
  12. Fauth, J. E., W. J. Resetarits Jr and H. M. Wilbur. 1990. Interactions between larval salamanders: a case of competitive equality. Oikos 58:91–99.CrossRefGoogle Scholar
  13. Fisher Huckins, C. J. 1997. Functional linkages among morphology, feeding performance, diet, and competitive ability in mollus-civorous sunfish. Ecology 78:2401–2414.CrossRefGoogle Scholar
  14. Gehlbach, F.R. and S. E. Kennedy. 1978. Population ecology of a highly productive aquatic salamander (Siren intermedia). Southwest. Nat. 23:423–430.CrossRefGoogle Scholar
  15. Gehlbach, F.R., R. Gordon and J. B. Neill. 1973. Aestivation of the salamander, Siren intermedia. Am. Midl. Nat. 89:455–463.CrossRefGoogle Scholar
  16. Gill, D. E. 1978. The metapopulation dynamics of the red spotted newt, Notophthalmus viridescens (Rafinesque). Ecol. Monogr. 48:145–166.CrossRefGoogle Scholar
  17. Gill, D. E. 1979. Density dependence and homing behavior in adult red-spotted newts Notophthalmus viridescens (Rafinesque). Ecology 60:800–813.CrossRefGoogle Scholar
  18. Godley, J .S. 1983. Observations on the courtship, nests and young of Siren intermedia in southern Florida. Am. Midl. Nat. 110:215–219.CrossRefGoogle Scholar
  19. Hamilton, W. J. Jr. 1940. The feeding habits of larval newts with reference to availability and predilection of food items. Ecology 21:351–356.CrossRefGoogle Scholar
  20. Harris, R. N. 1987a. Density-dependent paedomorphosis in the salamander Notophthalmus viridescens dorsalis. Ecology 68:705–712.CrossRefGoogle Scholar
  21. Harris, R. N. 1987b. An experimental study of population regulation in the salamander, Notophthalmus viridescens dorsalis (Urodela: Salamandridae). Oecologia 71: 280–285.CrossRefPubMedPubMedCentralGoogle Scholar
  22. Harris, R. N., R. A. Alford and H. M. Wilbur. 1988. Density and phenology of Notophthalmus viridescens dorsalis in a natural pond. Herpetologica 4:234–242.Google Scholar
  23. Martof, B. S. 1969. Prolonged inanation in Siren lacertina. Copeia 1969:285–289.CrossRefGoogle Scholar
  24. Martof, B. S. 1973. Siren intermedia. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles: 127.1–127.3.Google Scholar
  25. Mittlebach, G. G., C. W. Osenberg and M. A.Leibold. 1988. Trophic relations and ontogenetic niche shifts in aquatic ecosystems. In: B. Ebenman and L. Persson (eds.), Size-structured Populations: Ecology and Evolution. Springer-Verlag, Berlin, pp. 219–235.CrossRefGoogle Scholar
  26. Morin, P. J. 1981. Predatory salamanders reverse the outcome of competition among three species of anuran tadpoles. Science 212:1284–1286.CrossRefPubMedPubMedCentralGoogle Scholar
  27. Morin, P. J. 1983a. Predation, competition, and the structure of larval anuran guilds. Ecol. Monogr. 53: 119–138.CrossRefGoogle Scholar
  28. Morin, P. J. 1983b. Competitive and predatory interactions in natural and experimental populations of Notophthalmus viridescens dorsalis and Ambystoma tigrinum. Copeia 1983:628–639.CrossRefGoogle Scholar
  29. Muotka, T. 1990. Coexistence in a guild of filter-feeding caddis larvae: do different instars act as different species? Oecologia 85:281–292.CrossRefPubMedPubMedCentralGoogle Scholar
  30. Norberg, R. A. 1988. Self-thinning of plant populations dictated by packing density and individual growth geometry and relationships between animal population density and body mass governed by metabolic rate. In: B. Ebenman and L. Persson (eds.), Size-structured Populations: Ecology and Evolution. Springer-Verlag, Berlin, pp. 259–279.CrossRefGoogle Scholar
  31. Persson, L. 1985. Asymmetrical competition: Are larger animals competitively superior? Am. Nat. 126:261–266.CrossRefGoogle Scholar
  32. Persson, L. 1988. Asymmetries in competitive and predatory interactions in fish populations. In: B. Ebenman and L. Persson (eds.), Size-structured Populations: Ecology and Evolution. Springer-Verlag, Berlin, pp. 203–218.CrossRefGoogle Scholar
  33. Persson, L., and P. Eklov. 1995. Prey refuges affecting interactions between piscivorous perch and juvenile perch and roach. Ecology 76:70–81.CrossRefGoogle Scholar
  34. Polis, G. A. 1984. Age structure component of niche width and intraspecific resource partitioning: can age groups function as ecological species? Am. Nat. 123:541–564.CrossRefGoogle Scholar
  35. Polis, G. A. 1988. Exploitation competition and the evolution of interference, cannibalism, and intraguild predation in age/size-structured populations. In: B. Ebenman and L. Persson (eds.), Size-structured Populations: Ecology and Evolution. Springer-Verlag, Berlin, pp. 185–202.CrossRefGoogle Scholar
  36. Polis, G. A. and S. J. McCormick. 1987. Intraguild predation and competition among desert scorpions. Ecology 68:332–343.CrossRefGoogle Scholar
  37. Reilly, S. R. 1987. Ontogeny of the hyobranchial apparatus in the salamanders Ambystoma talpoideum (Ambystomatidae) and Notophthalmus viridescens (Salamandridae): the ecological morphology of two neotenic strategies. J. Morph. 191:205–214.CrossRefGoogle Scholar
  38. Resetarits, W. J., Jr. 1995a. Competitive asymmetry and coexistence in size-structured populations of brook trout and spring salamanders. Oikos 73: 188–198.CrossRefGoogle Scholar
  39. Resetarits, W. J., Jr. 1995b. Limiting similarity and the intensity of competitive effects on the mottled sculpin, Cottus bairdi, in experimental stream communities. Oecologia 104: 31–38.CrossRefPubMedPubMedCentralGoogle Scholar
  40. Resetarits, W. J., Jr. 1997. Interspecific competition and qualitative competitive asymmetry between two benthic stream fish. Oikos 78:429–439.CrossRefGoogle Scholar
  41. Resetarits, W. J., Jr. and J. E. Fauth. 1998. From cattle tanks to Carolina Bays: the utility of model systems for understanding natural communities. In: W. J. Resetarits, Jr. and J. Bernardo (eds.), Experimental Ecology: Issues and Perspectives. Oxford University Press, Oxford. pp. 133–151.Google Scholar
  42. Scroggin, J. B. and W. B. Davis. 1956. Food habits of the Texas dwarf sirens. Herpetologica 12:231–237.Google Scholar
  43. Szabo, A. R. 2002. Experimental tests of intercohort competition for food and cover in the tidepool sculpin (Oligocottus maculosus Girard). Can. J. Zool. 80:137–144.CrossRefGoogle Scholar
  44. Takimoto, G. 2003. Adaptive plasticity in ontogenetic niche shifts stabilizes consumer-resource dynamics. Am. Nat. 162:93–109.CrossRefPubMedPubMedCentralGoogle Scholar
  45. Taylor, B. J., R. A. Estes, J. H. K. Pechmann and R. D. Semlitsch. 1988. Trophic relationships in a temporary pond: larval salamanders and their macroinvertebrate prey. Can. J. Zool. 68:2191–2198.CrossRefGoogle Scholar
  46. Van Buskirk, J. 1993. Population consequences of crowding in the dragonfly Aeshna juncea. Ecology 74:1950–1958.CrossRefGoogle Scholar
  47. Verrell, P. 1986. Wrestling in the red-spotted newt (Notophthalmus viridescens): resource value and contestant asymmetry determine contest duration and outcome. Anim. Behav. 34:398–402.CrossRefGoogle Scholar
  48. Warner, R. R. and P. L. Chesson. 1985. Coexistence mediated by recruitment fluctuations: a field guide to the storage effect. Am. Nat. 125:769–787.CrossRefGoogle Scholar
  49. Werner, E. E. 1986. Species interactions in freshwater fish communities. In: J. Diamond and T. E. Case (eds.), Community Ecology. Harper and Row, New York, pp. 344–358.Google Scholar
  50. Werner, E. E. 1988. Size, scaling and the evolution of complex life cycles. In: B. Ebenman and L. Persson (eds.), Size-structured Populations: Ecology and Evolution. Springer-Verlag, Berlin, pp. 60–81.CrossRefGoogle Scholar
  51. Werner, E. E. 1994. Ontogenetic scaling of competitive interactions: size-dependent effects and responses in two anuran larvae. Ecology 75:197–213.CrossRefGoogle Scholar
  52. Werner, E. E. and J. F. Gilliam. 1984. The ontogenetic niche and species interactions in size-structured populations. Ann. Rev. Ecol. Syst. 15:393–425.CrossRefGoogle Scholar
  53. Wilbur, H. M. 1980. Complex life cycles. Ann. Rev. Ecol. Syst. 11:67–93.CrossRefGoogle Scholar
  54. Wilbur, H. M. 1984. Complex life cycles and community organization in amphibians. In: P. W. Price, C. N. Slobodchikoff, and W. S. Gaud (eds.), A New Ecology: Novel Approaches to Interactive Systems. Wiley, New York, pp. 195–224.Google Scholar
  55. Wilbur, H. M. 1987. Regulation of structure in complex systems: experimental temporary pond communities. Ecology 68:1437–1452.CrossRefGoogle Scholar
  56. Wilbur, H. M. 1988. Interactions between growing predators and growing prey. In: B. Ebenman and L. Persson (eds.), Size-structured Populations: Ecology and Evolution. Springer-Verlag, Berlin, pp. 157–172.CrossRefGoogle Scholar
  57. Wilson, D. S. 1975. The adequacy of body size as a niche difference. Am. Nat. 109:769–784.CrossRefGoogle Scholar
  58. Wissinger, S. A. 1992. Niche overlap and the potential for competition and intraguild predation between size-structured populations. Ecology 73:1431–1444.CrossRefGoogle Scholar

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© Akadémiai Kiadó, Budapest 2005

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Authors and Affiliations

  1. 1.Program in Ecology, Evolution, and Integrative Biology, Department of Biological SciencesOld Dominion UniversityNorfolkUSA
  2. 2.Department of BiologyUniversity of Central FloridaOrlandoUSA

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