Multilevel Models for the Distribution of Hosts and Symbionts

• Published in: PloS one Vol. 11; no. 11; p. e0165768
• Main Authors: Joseph, Maxwell B, Stutz, William E, Johnson, Pieter T J
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.11.2016; Public Library of Science (PLoS)
• Subjects: Abundance; Algorithms; Amphibia; Amphibians; Amphibians - microbiology; Amphibians - parasitology; Amphibians - physiology; Amphibians - virology; Analysis; Animals; Batrachochytrium dendrobatidis; Biology and Life Sciences; Constraint modelling; Correlation; Disease; Disease transmission; Ecology; Ecology and Environmental Sciences; Ecosystem; Environment models; Environmental factors; Evolution; Evolutionary biology; Fungi; Fungi - physiology; Helminths - physiology; Host-Parasite Interactions; Medicine and Health Sciences; Models, Biological; Multivariate analysis; Parasites; Physical Sciences; Population biology; Population Dynamics; Probability; Ranavirus - physiology; Sampling; Sampling designs; Species; Symbionts; Symbiosis; United States > US; Colorado
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0165768

Symbiont occurrence is influenced by host occurrence and vice versa, which leads to correlations in host-symbiont distributions at multiple levels. Interactions between co-infecting symbionts within host individuals can cause correlations in the abundance of two symbiont species across individual hosts. Similarly, interactions between symbiont transmission and host population dynamics can drive correlations between symbiont and host abundance across habitat patches. If ignored, these interactions can confound estimated responses of hosts and symbionts to other factors. Here, we present a general hierarchical modeling framework for distributions of hosts and symbionts, estimating correlations in host-symbiont distributions at the among-site, within-site, among-species, and among-individual levels. We present an empirical example from a multi-host multi-parasite system involving amphibians and their micro- and macroparasites. Amphibian hosts and their parasites were correlated at multiple levels of organization. Macroparasites often co-infected individual hosts, but rarely co-infected with the amphibian chytrid fungus. Such correlations may result from interactions among parasites and hosts, joint responses to environmental factors, or sampling bias. Joint host-symbiont models account for environmental constraints and species interactions while partitioning variance and dependence in abundance at multiple levels. This framework can be adapted to a wide variety of study systems and sampling designs.