Abstract

As primary determinants of microbial community dynamics, viruses play a central role in key ecological processes, including respiration, organic and inorganic nutrient cycling, and greenhouse gas production and sequestration. However, the majority of studies of viruses in natural environments are from oceans, where the size and complexity of ecological communities pose major challenges for studying detailed mechanisms and gaining a full picture of host-virus networks. We characterize viruses in 16 metagenomes from carnivorous pitcher plant natural microcosms, which are an emerging model system for studying community ecology and ecosystem function. We find that pitcher plant microcosms possess a relatively high proportion of lysogenic viruses compared to other freshwater systems. In addition, viruses from pitcher plant microcosms appear to possess auxiliary metabolic genes for chitin degradation, an important ecological function in pitcher plants where the primary energy source is the plant's insect prey. The reduced size and complexity of pitcher plant natural microcosms, as well as their well-defined ecological function, position them as an excellent model system for characterizing whole host-virus networks and understanding the mechanisms through which viruses alter microbial diversity and function.