Sierra Nevada Aquatic Research Laboratory

31 May, 05 PM - 29 Jun, 05 PM

Emerging infectious diseases can have dramatic effects on their host populations. In wildlife species, there are many recent examples of novel pathogens invading naive populations, with different pathogens resulting in very different outcomes on their hosts. In some systems, the pathogen sweeps through the local population causing a single outbreak (?epizootic?), after which the pathogen goes locally extinct as the pool of susceptible hosts is depleted. In other systems, following initial arrival of the pathogen and subsequent host population crash, the host-pathogen system reaches a new ?enzootic? state in which pathogen and host persist, potentially with reduced host population density. In the Sierra Nevada of California, we have documented both of these types of outcomes (epizootics resulting in local extinction of the host and enzootic host-pathogen persistence) in a single host-pathogen system. The pathogen is the amphibian chytrid fungus, Batrachochytrium dendrobatidis (hereafter, ?Bd?), which causes the disease, chytridiomycosis, and is implicated as one of the major causes of amphibian declines world-wide. In the Sierra Nevada, the primary amphibian host is the mountain yellow-legged frog, Rana muscosa, once a common amphibian that has declined precipitously in recent decades. Based on our previous research, invasion of Bd into the remaining uninfected R. muscosa populations appears inevitable within the next few years. Therefore, the best chance for the survival of R. muscosa (and many other similarly-impacted amphibians) is persistence in the presence of Bd. It is critically important, therefore, to understand the factors allowing for host persistence in the enzootic state. In the proposed research, we will parameterize and test a model of the R. muscosa/Bd interaction that includes within-host Bd dynamics and host stage-structure, and we will test four non-mutually exclusive hypotheses that could account for different disease outcomes. These are that population extinction versus persistence is the result of inter-population differences in (1) density-dependent disease dynamics, (2) Bd virulence, (3) frog susceptibility, and/or (4) environmental conditions. Results from this research will have important implications for the management of wildlife populations in a world in which the emergence of novel diseases is increasingly common.

Visit #14488 @Sierra Nevada Aquatic Research Laboratory

Approved

Under Project # 9518 | Research

Factors allowing amphibian persistence following disease outbreaks

research_scientist - University of California, Santa Barbara

Reservation Members(s)

Group of 3 Research Assistant (non-student/faculty/postdoc) May 31 - Sep 14, 2008 (107 days)
Roland Knapp May 31 - Sep 14, 2008 (107 days)
Roland Knapp May 31, 2008 - Jun 29, 2009 (395 days)

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Q1 5 May 31 - Sep 14, 2008