Contrasting patterns of activity in fungal and bacterial communities along a natural environmental gradient

Background/Question/Methods

Dormancy is thought to promote biodiversity within microbial communities, and could be important for survival of taxa in the face of climate change, but little is known about how active and dormant communities respond to changing environmental conditions. Using targeted sequencing of ribosomal markers, we examined patterns of dormancy in bacterial and fungal communities colonizing decomposing litter along a natural environmental gradient of maple forests spanning 415 km.

Results/Conclusions

For both the fungi and bacteria, the composition of active and dormant communities was distinct, but both were composed of phylogenetically clustered groups. Opposing patterns of phylogenetic clustering were found for the fungi and bacteria; for fungi, phylogenetic clustering was significantly higher in the dormant community compared to the active community, but the opposite pattern was found for the bacteria. Across the environmental gradient, the degree of phylogenetic clustering in the active bacterial communities declined with increasing pH and decreasing carbon to nitrogen ratio, but communities were always significantly more clustered than predicted from the null model. No significant correlations were found for the fungal community. Our results suggest that dormancy structures bacterial and fungal communities in different ways, and that community assembly of active bacterial communities is strongly affected by environmental conditions, even over relatively short gradients.