Spatial and temporal variation in Ambystoma tigrinum virus (ATV) infection prevalence in a persisting Ambystoma tigrinum population on the Kaibab Plateau, AZ.
Greer, Amy*,1, Collins, James1, 1 Arizona State University, Tempe, AZ
ABSTRACT- Disease is thought to play an important role in amphibian declines. Observations across a broad range of biological systems suggest that the interaction between amphibian hosts and their pathogens is complex with prevalence influenced by characteristics of the host, pathogen, and environment. Ranaviruses (including ATV) are directly transmitted and associated with epidemics, but do not appear to be linked to long term population declines or extinctions. Field surveys of Ambystoma tigrinum were conducted on the Kaibab Plateau, AZ, within a single host-pathogen system where ATV and its salamander host have persisted for many years. We examined the variation in disease prevalence over time and across the landscape. Tissue samples collected in the field were analysed for the presence of ATV using polymerase chain reaction (PCR). Disease prevalence within a pond varied significantly between years (p=0.002) from as high as 44% (2004) to as low as 4% (2005) in the same pond. Variation in infection prevalence between years is likely related to differences in water availability. During wet seasons (2005), ponds flooded for the entire growing season, which decreased larval density, reduced the contact rate of individuals, and decreased disease transmission. This would account for the change in infection prevalence observed between 2004, a dry year, and 2005 when it was wet. Experimental work is underway to test this hypothesis. Evaluating the complex interactions between hosts and their pathogens will allow us to better understand the mechanisms driving amphibian persistence and extinction.
Key words: Ambystoma tigrinum, disease ecology, amphibian decline
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