All organic life, by virtue of having ever been alive, is fated to end. Life and death represent opposing binary states: an organism is either alive and its biological processes functioning, or dead, with those processes halting entirely. Of the phenomena that only carbon-based life can lay claim to, the decomposition that accompanies death stands out as the most ubiquitous. The connotation of decomposition often betrays its nature as a complex, multivariate process that is mediated by far more than just the carcass enabling it. Among the decomposers responsible for nutrient cycling in carrion systems, bacteria and blow flies (Diptera: Calliphoridae) stand out as the most effectual. The objective of this study was to examine how the microbiota of carcasses, blow fly larvae, and larval masses developed as decomposition advanced. The intent to monitor bacterial community succession with repeated measures was motivated by growing interest among researchers to properly identify and characterize core contributors of the ecological networks supported by carrion, otherwise known as the “necrobiome.” To account for abiotic factors that we suspected play a role in moderating these ecosystems, we evaluated the role seasonal weather dynamics play in influencing microbiome assemblage. We predicted that postmortem microbiome composition, diversity, and succession would be drastically dissimilar between seasons by seasonal weather conditions. It was additionally hypothesized that colonization of carcasses by blow flies would significantly impact carcass bacterial community composition. Parallel predictions were made that season would, similarly, influence larval microbiome assemblage as well as the microbiota of larval masses formed by those larvae. Ultimately, we found both season and larval presence jointly influenced postmortem microbiome succession, and that postmortem microbiome diversity was significantly greater in the summer than the fall or spring, but that no significant difference existed between the fall and spring seasons themselves. Bacterial community composition differed significantly by season regardless of pairwise comparison. Blow fly colonization significantly influenced bacterial community composition in facilitating the introduction and subsequent dominance of insect-associated bacterial taxa like Ignatzschineria. Season made the most significant contributions to microbiome dissimilarity driven by humidity. These decomposition studies demonstrated the interconnectedness of life encompassed by the necrobiome and, in doing so, strengthened pretense to better evaluate inter-kingdom interactions observed in decomposition settings.
Read
