, Volume 166, Issue 4, pp 1029–1041

Individual and combined effects of multiple pathogens on Pacific treefrogs


    • Department of ZoologyOregon State University
  • Pieter T. J. Johnson
    • Department of Ecology and Evolutionary BiologyUniversity of Colorado
  • Catherine L. Searle
    • Department of ZoologyOregon State University
  • James E. Johnson
    • Department of Biological SciencesCentral Washington University
  • Tate S. Tunstall
    • Department of Ecology, Evolution and Marine BiologyUniversity of California, Santa Barbara
  • Barbara A. Han
    • Odum School of EcologyUniversity of Georgia
  • Jason R. Rohr
    • Department of Integrative BiologyUniversity of South Florida
  • Andrew R. Blaustein
    • Department of ZoologyOregon State University
Community ecology - Original Paper

DOI: 10.1007/s00442-011-1932-1

Cite this article as:
Romansic, J.M., Johnson, P.T.J., Searle, C.L. et al. Oecologia (2011) 166: 1029. doi:10.1007/s00442-011-1932-1


In nature, individual hosts often encounter multiple pathogens simultaneously, which can lead to additive, antagonistic, or synergistic effects on hosts. Synergistic effects on infection prevalence or severity could greatly affect host populations. However, ecologists and managers often overlook the influence of pathogen combinations on hosts. This is especially true in amphibian conservation, even though multiple pathogens coexist within amphibian populations, and several pathogens have been implicated in amphibian population declines and extinctions. Using an amphibian host, Pseudacris regilla (Pacific treefrog), we experimentally investigated interactive effects among three pathogens: the trematode Ribeiroia sp. (hereafter, Ribeiroia), the fungus Batrachochytrium dendrobatidis (hereafter, BD), and the water mold Achlya flagellata. We detected no effects of A. flagellata, but did find effects of Ribeiroia and BD that varied depending on context. Low doses of Ribeiroia caused relatively few malformations, while higher Ribeiroia doses caused numerous deformities dominated by missing and reduced limbs and limb elements. Exposure to low doses of BD accelerated larval host development, despite there being no detectable BD infections, while exposure to higher BD doses caused infection but did not alter developmental rate. Hosts exposed to both Ribeiroia and BD exhibited the highest mortality, although overall evidence of interactive effects of multiple pathogens was limited. We suggest further research on the influence of multi-pathogen assemblages on amphibians, particularly under a variety of ecological conditions and with a wider diversity of hosts and pathogens.


CoinfectionConcomitant infectionsPolyparasitismEmerging infectious diseaseAmphibian decline

Supplementary material

442_2011_1932_MOESM1_ESM.doc (104 kb)
Supplementary material 1 (DOC 104 kb)

Copyright information

© Springer-Verlag 2011