Gut passage of epigeous ectomycorrhizal fungi by two opportunistic mycophagous rodents

Mycophagists can influence fungal diversity within their home ranges by ensuring the continued and effective dis- persal of spores from one site to another. However, the passage of spores through the digestive tract of vertebrates can affect the activity and viability of the spores ingested. This phenomenon has been rarely documented in opportunistic mycophagists con- suming epigeous fungi. Using laboratory experiments, we investigated the activity and viability of spores of two epigeous ecto- mycorrhizal fungal species (Laccaria trichodermophora and Suillus tomentosus) after passage through the digestive tract of two opportunistic mycophagous small rodents, the volcano mouse Peromyscus alstoni and the deer mouse P. maniculatus. We found that passage through the gut of either species of rodent had a significant effect on spore activity and viability for both fungal species. The proportion of active spores (0.37-0.40) of L. trichodermophora in the feces of both species of rodents was less than that recorded for the control (0.82). However, the proportion of active spores (0.64-0.73) of S. tomentosus in the feces of each species of rodent was higher than in the control (0.40). On the other hand, the viability of spores was lower (0.26-0.30 in L. trichodermophora and 0.60-0.69 in S. tomentosus) for both fungi when consumed by either rodent relative to the controls (0.90 in L. trichodermophora and 0.82 in S. tomentosus). These findings suggest that these rodent species may be effective dispersers of both epigeous fungi (Current Zoology 57 (3): 293-299, 2011).