Dangerfield, C. R. | Search bioRxiv

bioRxiv2019

Succession of bacterial communities on carrion is independent of vertebrate scavengers

The decomposition of carrion is carried out by a suite of macro- and micro-organisms who interact with each other in a variety of ecological contexts. The ultimate result of carrion decomposition is the recycling of carbon and nutrients from the carrion back into the ecosystem. Exploring these ecological interactions among animals and microbes is a critical aspect of understanding the nutrient cycling of an ecosystem. Here we investigate the potential impacts that vertebrate scavenging may have on the microbial community of carrion. In this study, we placed seven juvenile domestic cow carcasses in the Grassy Mountain region of Utah, USA and collected tissue samples at periodic intervals. Using high-depth environmental sequencing of the 16S rRNA gene and camera trap data, we documented the microbial community shifts associated with decomposition and with vertebrate scavenger visitation. The remarkable scarcity of animals at our study site enabled us to examine natural carrion decomposition in the near absence of animal scavengers. Our results indicate that the microbial communities of carcasses that experienced large amounts of scavenging activity were not significantly different than those carcasses that observed very little scavenging activity. Rather, the microbial community shifts reflected changes in the stage of decomposition similar to other studies documenting the successional changes of carrion microbial communities. Our study suggests that microbial community succession on carrion follows consistent patterns that are largely unaffected by scavenging.

microbiology↗

bioRxiv2016

Bacterial communities affected by experimental disturbances to canopy soils of a temperate rainforest

Trees of temperate rainforests host a large biomass of epiphytes, living plants associated with soils formed in the forest canopy. This study provides the first characterization of bacterial communities in canopy soils enabled by high-depth environmental sequencing of 16S rRNA genes. Canopy soil included many of the same major taxonomic groups of Bacteria that are also found in ground soil, but canopy bacterial communities were lower in diversity and contained different species-level operational taxonomic units. A field experiment was conducted to document changes in the bacterial communities of soils associated with epiphytic material that falls to the forest floor. Bacterial diversity and composition of canopy soil was highly similar, but not identical, to adjacent ground soil two years after transfer to the forest floor, indicating that canopy bacteria are almost, but not completely, replaced by ground soil bacteria. Furthermore, soil associated with epiphytic material on branches that were severed from the host tree and suspended in the canopy contained altered bacterial communities that were distinct from those in canopy material moved to the forest floor. Therefore, connection to the living tree is an important factor in the ecology of canopy soil bacteria. These results represent an initial survey of bacterial diversity of the canopy and provide a foundation upon which future studies can more fully investigate the ecological and evolutionary dynamics of these communities.\n\nIMPORTANCETemperate rainforests host large accumulations of epiphytes, plants that live on the branches of trees. This study provides a first look at the unique nature of bacterial communities in soil that is formed by the decomposition of epiphytes in the canopy of a temperate rainforest. Falling of epiphytic material results in the transfer of significant amounts of carbon and nutrients from the canopy to the forest floor. This study also experimentally documented how soil bacterial communities are affected by their movement from the canopy to the forest floor. The bacterial composition of canopy soil was altered by the severing of the epiphytic material from the living tree, even when the epiphytes remained in the canopy. Therefore, the unique nature of canopy soil bacteria is determined in part by the living host tree and not only by the physical environmental conditions associated with the canopy.

microbiology↗