全球变化知识资源中心

The Yosemite Toad (Anaxyrus canorus) has experienced declines in distribution and abundance in recent decades. The declines in this species have been anecdotally attributed to infectious disease and increased frequency and intensity of drought, but neither of these factors have been formally tested. We investigated the combined effects of reduced water availability and susceptibility to the disease chytridiomycosis across A. canorus life stages. Specifically, we reared A. canorus tadpoles under drying conditions and exposed metamorphosed toadlets to Batrachochytrium dendrobatidis (Bd), the pathogenic fungus that causes the lethal disease chytridiomycosis. We examined (1) the time to and size at metamorphosis of A. canorus tadpoles reared under drying conditions, (2) the susceptibility of post-metamorphic A. canorus to Bd, and (3) the synergistic effects of drying conditions and disease on post-metamorphic toadlet survival. We found that recently metamorphosed A. canorus toadlets are highly susceptible to lethal Bd infection. Although we did not detect an effect of reduced water availability on disease risk, we suggest follow-up experiments in both the laboratory and the field to better understand the direct and indirect roles that drought and disease play in A. canorus population declines.