Skip to main content
  • Submit
  • About
    • Editorial Board
    • PNAS Staff
    • FAQ
    • Rights and Permissions
    • Site Map
  • Contact
  • Journal Club
  • Subscribe
    • Subscription Rates
    • Subscriptions FAQ
    • Open Access
    • Recommend PNAS to Your Librarian
  • Log in
  • My Cart

Main menu

  • Home
  • Articles
    • Current
    • Latest Articles
    • Special Features
    • Colloquia
    • Collected Articles
    • PNAS Classics
    • Archive
  • Front Matter
  • News
    • For the Press
    • Highlights from Latest Articles
    • PNAS in the News
  • Podcasts
  • Authors
    • Information for Authors
    • Purpose and Scope
    • Editorial and Journal Policies
    • Submission Procedures
    • For Reviewers
    • Author FAQ
  • Submit
  • About
    • Editorial Board
    • PNAS Staff
    • FAQ
    • Rights and Permissions
    • Site Map
  • Contact
  • Journal Club
  • Subscribe
    • Subscription Rates
    • Subscriptions FAQ
    • Open Access
    • Recommend PNAS to Your Librarian

User menu

  • Log in
  • My Cart

Search

  • Advanced search
Home
Home

Advanced Search

  • Home
  • Articles
    • Current
    • Latest Articles
    • Special Features
    • Colloquia
    • Collected Articles
    • PNAS Classics
    • Archive
  • Front Matter
  • News
    • For the Press
    • Highlights from Latest Articles
    • PNAS in the News
  • Podcasts
  • Authors
    • Information for Authors
    • Purpose and Scope
    • Editorial and Journal Policies
    • Submission Procedures
    • For Reviewers
    • Author FAQ

New Research In

Physical Sciences

Featured Portals

  • Physics
  • Chemistry
  • Sustainability Science

Articles by Topic

  • Applied Mathematics
  • Applied Physical Sciences
  • Astronomy
  • Computer Sciences
  • Earth, Atmospheric, and Planetary Sciences
  • Engineering
  • Environmental Sciences
  • Mathematics
  • Statistics

Social Sciences

Featured Portals

  • Anthropology
  • Sustainability Science

Articles by Topic

  • Economic Sciences
  • Environmental Sciences
  • Political Sciences
  • Psychological and Cognitive Sciences
  • Social Sciences

Biological Sciences

Featured Portals

  • Sustainability Science

Articles by Topic

  • Agricultural Sciences
  • Anthropology
  • Applied Biological Sciences
  • Biochemistry
  • Biophysics and Computational Biology
  • Cell Biology
  • Developmental Biology
  • Ecology
  • Environmental Sciences
  • Evolution
  • Genetics
  • Immunology and Inflammation
  • Medical Sciences
  • Microbiology
  • Neuroscience
  • Pharmacology
  • Physiology
  • Plant Biology
  • Population Biology
  • Psychological and Cognitive Sciences
  • Sustainability Science
  • Systems Biology
Research Article

Biodiversity inhibits parasites: Broad evidence for the dilution effect

David J. Civitello, Jeremy Cohen, Hiba Fatima, Neal T. Halstead, Josue Liriano, Taegan A. McMahon, C. Nicole Ortega, Erin Louise Sauer, Tanya Sehgal, Suzanne Young, and Jason R. Rohr
PNAS July 14, 2015 112 (28) 8667-8671; first published June 11, 2015 https://doi.org/10.1073/pnas.1506279112
David J. Civitello
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • For correspondence: civitello@usf.edu
Jeremy Cohen
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Hiba Fatima
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Neal T. Halstead
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Josue Liriano
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Taegan A. McMahon
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
C. Nicole Ortega
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Erin Louise Sauer
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Tanya Sehgal
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Suzanne Young
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Jason R. Rohr
Department of Integrative Biology, University of South Florida, Tampa, FL 33620
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  1. Edited by Simon A. Levin, Princeton University, Princeton, NJ, and approved May 15, 2015 (received for review March 30, 2015)

This article has a Letter. Please see:

  • Public health perspective on patterns of biodiversity and zoonotic disease

See related content:

  • Lose biodiversity, gain disease
    - Jul 14, 2015

See related content:

  • Reply to Salkeld et al.: Diversity-disease patterns are robust to study design, selection criteria, and publication bias
    - Nov 17, 2015
  • Article
  • Figures & SI
  • Info & Metrics
  • PDF
Loading

Significance

The dilution effect hypothesis suggests that diverse ecological communities limit disease spread via several mechanisms. Therefore, biodiversity losses could worsen epidemics that harm humans and wildlife. However, there is contentious debate over whether the hypothesis applies broadly, especially for parasites that infect humans. We address this fundamental question with a formal meta-analysis of >200 assessments relating biodiversity to disease in >60 host–parasite systems. We find overwhelming evidence of dilution, which is independent of host density, study design, and type and specialization of parasites. A second analysis identified similar effects of diversity in plant–herbivore systems. Thus, biodiversity generally decreases parasitism and herbivory. Consequently, human-induced declines in biodiversity could increase human and wildlife diseases and decrease crop and forest production.

Abstract

Infectious diseases of humans, wildlife, and domesticated species are increasing worldwide, driving the need to understand the mechanisms that shape outbreaks. Simultaneously, human activities are drastically reducing biodiversity. These concurrent patterns have prompted repeated suggestions that biodiversity and disease are linked. For example, the dilution effect hypothesis posits that these patterns are causally related; diverse host communities inhibit the spread of parasites via several mechanisms, such as by regulating populations of susceptible hosts or interfering with parasite transmission. However, the generality of the dilution effect hypothesis remains controversial, especially for zoonotic diseases of humans. Here we provide broad evidence that host diversity inhibits parasite abundance using a meta-analysis of 202 effect sizes on 61 parasite species. The magnitude of these effects was independent of host density, study design, and type and specialization of parasites, indicating that dilution was robust across all ecological contexts examined. However, the magnitude of dilution was more closely related to the frequency, rather than density, of focal host species. Importantly, observational studies overwhelmingly documented dilution effects, and there was also significant evidence for dilution effects of zoonotic parasites of humans. Thus, dilution effects occur commonly in nature, and they may modulate human disease risk. A second analysis identified similar effects of diversity in plant–herbivore systems. Thus, although there can be exceptions, our results indicate that biodiversity generally decreases parasitism and herbivory. Consequently, anthropogenic declines in biodiversity could increase human and wildlife diseases and decrease crop and forest production.

  • biodiversity
  • parasitism
  • dilution effect
  • associational resistance
  • meta-analysis

Footnotes

  • ↵1To whom correspondence should be addressed. Email: civitello{at}usf.edu.
  • ↵2J.C., H.F., N.T.H., J.L., T.A.M., C.N.O., E.L.S., T.S., and S.Y. contributed equally to this work.

  • ↵3Present address: Department of Biology, University of Tampa, Tampa, FL 33606.

  • Author contributions: D.J.C. and J.R.R. designed research; D.J.C., J.C., H.F., N.T.H., J.L., T.A.M., C.N.O., E.L.S., T.S., S.Y., and J.R.R. performed research; D.J.C. and J.R.R. analyzed data; and D.J.C. and J.R.R. wrote the paper.

  • The authors declare no conflict of interest.

  • This article is a PNAS Direct Submission.

  • See Commentary on page 8523.

  • This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1506279112/-/DCSupplemental.

View Full Text
PreviousNext
Back to top
Article Alerts
Email Article

Thank you for your interest in spreading the word on PNAS.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Biodiversity inhibits parasites: Broad evidence for the dilution effect
(Your Name) has sent you a message from PNAS
(Your Name) thought you would like to see the PNAS web site.
Citation Tools
Broad evidence for the dilution effect hypothesis
David J. Civitello, Jeremy Cohen, Hiba Fatima, Neal T. Halstead, Josue Liriano, Taegan A. McMahon, C. Nicole Ortega, Erin Louise Sauer, Tanya Sehgal, Suzanne Young, Jason R. Rohr
Proceedings of the National Academy of Sciences Jul 2015, 112 (28) 8667-8671; DOI: 10.1073/pnas.1506279112

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Request Permissions
Share
Broad evidence for the dilution effect hypothesis
David J. Civitello, Jeremy Cohen, Hiba Fatima, Neal T. Halstead, Josue Liriano, Taegan A. McMahon, C. Nicole Ortega, Erin Louise Sauer, Tanya Sehgal, Suzanne Young, Jason R. Rohr
Proceedings of the National Academy of Sciences Jul 2015, 112 (28) 8667-8671; DOI: 10.1073/pnas.1506279112
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Mendeley logo Mendeley
Proceedings of the National Academy of Sciences: 116 (49)
Current Issue

Submit

Sign up for Article Alerts

Article Classifications

  • Biological Sciences
  • Ecology

Jump to section

  • Article
    • Abstract
    • Results and Discussion
    • Materials and Methods
    • Acknowledgments
    • Footnotes
    • References
  • Figures & SI
  • Info & Metrics
  • PDF

You May Also be Interested in

Modulating the body's networks could become mainstream therapy for many health issues. Image credit: The Feinstein Institutes for Medicine Research.
Core Concept: The rise of bioelectric medicine sparks interest among researchers, patients, and industry
Modulating the body's networks could become mainstream therapy for many health issues.
Image credit: The Feinstein Institutes for Medicine Research.
Adaptations in heart structure and function likely enabled endurance and survival in preindustrial humans. Image courtesy of Pixabay/Skeeze.
Human heart evolved for endurance
Adaptations in heart structure and function likely enabled endurance and survival in preindustrial humans.
Image courtesy of Pixabay/Skeeze.
Viscoelastic carrier fluids enhance retention of fire retardants on wildfire-prone vegetation. Image courtesy of Jesse D. Acosta.
Viscoelastic fluids and wildfire prevention
Viscoelastic carrier fluids enhance retention of fire retardants on wildfire-prone vegetation.
Image courtesy of Jesse D. Acosta.
Water requirements may make desert bird declines more likely in a warming climate. Image courtesy of Sean Peterson (photographer).
Climate change and desert bird collapse
Water requirements may make desert bird declines more likely in a warming climate.
Image courtesy of Sean Peterson (photographer).
QnAs with NAS member and plant biologist Sheng Yang He. Image courtesy of Sheng Yang He.
Featured QnAs
QnAs with NAS member and plant biologist Sheng Yang He
Image courtesy of Sheng Yang He.

Similar Articles

Site Logo
Powered by HighWire
  • Submit Manuscript
  • Twitter
  • Facebook
  • RSS Feeds
  • Email Alerts

Articles

  • Current Issue
  • Latest Articles
  • Archive

PNAS Portals

  • Classics
  • Front Matter
  • Teaching Resources
  • Anthropology
  • Chemistry
  • Physics
  • Sustainability Science

Information

  • Authors
  • Editorial Board
  • Reviewers
  • Press
  • Site Map
  • PNAS Updates

Feedback    Privacy/Legal

Copyright © 2019 National Academy of Sciences. Online ISSN 1091-6490