What are the roles of host phylogeny, transmission variables, and host traits in molding parasite metacommunity structure? Find out in the new Early View paper “Relative importance of host environment, transmission potential and host phylogeny to the structure of parasite metacommunities” by Ted Dallas and Steven J Presley. Here’s their own summary of the paper:
Identification of mechanisms that shape parasite community and metacommunity structures have important implications to host health,disease transmission,and the understanding of community assembly in general. In addition, a metacommunity approach can enhance the understanding of parasitological relationships among hosts, which may be reservoirs for emerging diseases or act as vectors that transmit diseases to humans or agriculturally important domestic animals.
A metacommunity is typically defined as a set of ecological communities forming a network in space, such as fish communities from a series of lakes across a landscape. However, Mihaljevic (2012) recently argued that metacommunity theory could be used to better understand parasite ecology. In our study, we considered host species to represent sites, with each host species harboring a distinct community of parasites. Each host species has a unique set of traits that define the environment for the parasites, the likelihood of parasite transmission to other host species, and the co-evolutionary relationships between hosts and their parasites.
Figure 1: Parasite distributions among rodent host species. Parasite group identity is indicated by color of the text in the graphic below the figure (e.g. Coccidians are in green).
We used data on rodent parasites from the Sevilleta Long Term Ecological Research Study to investigate parasite metacommunity structure from two perspectives. First, we used the Elements of Metacommunity Structure (EMS) framework to determine if parasite species distributions among hosts formed coherent structures (Leibold and Mikkelson 2002). Second, we assessed the relative roles of host phylogeny, host traits that can affect parasite transmission (e.g. home range size, diet breadth), and host traits that define the environment (e.g. body size, trophic status, longevity), using a variance partitioning analysis.
Three distinct metacommunity structured occurred, Clementsian, quasi-Clementsian, and random. Despite the variation in structure, host environment explained the largest proportion of the variation in community structure (~30%). This highlights the fact that no a priori relationship exists between particular structuring mechanisms and particular metacommunity structures. This suite of distinct responses from the same host metacommunity highlight the complex and diverse nature of host-parasite systems with respect to how parasites move through the environment, variation in life histories, and level of host specialization they exhibit. Mechanisms that contribute to parasite metacommunity structure may be highly complex, as host metacommunities can exhibit complex responses to local and spatial processes, with responses of hosts to large-scale environmental variation and responses of parasites to variation in host characteristics all contributing to parasite metacommunity dynamics.
Leibold, M. and Mikkelson, G. 2002. Coherence, species turnover, and boundary clumping: elements of meta-community structure. – Oikos 97: 237–250.
Mihaljevic, JR. Linking metacommunity theory and symbiont evolutionary ecology. Trends in Ecology & Evolution.