JEN PECHAL, PHD
Carrion Ecology
Life does not end after death. Numerous organisms have evolved to use decomposing organic matter to complete their life cycle. The dynamics of the microbes and insects during the decomposition process is a key focus of our work. Our work is interested in determining the successional changes of microbial communities associated with insects (aquatic and terrestrial) based on functional and structural profiles. Specifically, delving into these interactions using basic ecological and next generation sequencing (NGS) approaches.
Microbial Communities
Microbial communities are commonly found in concert with decomposing heterotrophic biomass (e.g., carrion, dung,). Yet, there remains a paucity of knowledge about microbial community dynamics associated with decomposition. Given the rapid advancements in technology, identification of microbial taxa and their function using next-generation sequencing approaches is easier and more cost-effective than in the past.
Our work has shown significant microbial community (16S) structure differences in taxon richness and relative abundance patterns through the decomposition process of carrion. Further, we have documented microbial presence and successional patterns during decomposition across host species (e.g., humans, pigs, salmon) and geographic locations (e.g., Texas, Michigan, Indiana, Alaska). This work advances our knowledge of how microbes change during decomposition, and their applicability in forensic science.
Insect Communities
Many insects use decomposing organic material (e.g., carcasses, dung, plants) during their life cycle. Yet, the mechanisms governing attraction, consumption, and nutrient transformation of decaying ephemeral resources are only beginning to be thoroughly investigated. The introduction carrion into a terrestrial system has been reported to facilitate a localized succession of insect colonizers, such as blow flies and beetles. These insects play an functional role during the decomposition process.
Our work experimentally tests how necrophagous insect communities assembly, and how these biotic consortia impact the decomposition process in natural habitats. We have previously demonstrated that delayed insect access to carrion (insects excluded for five days) results in marked shifts in necrophagous insect community structure, turnover rates, and assembly with overall effects on carrion decomposition. his work improves our understanding of the biodiversity and dynamics of insect populations associated with carrion. Further, this work is important in a forensic context by determining when insects arrive to a body, which can be informative in estimating minimum periods of insect activity that often correspond to time since death.
Necrobiome Interactions
Decomposition is not an isolated event in time or space. Rather, this important ecosystem process driven by interacting communities of organisms ranging from microbes (bacteria, fungi) to insects (blow flies) to scavengers (vultures) across space and time. All organisms associated with decomposing organic material (plants and animals) are part of the necrobiome. The role of necrobiome was recognized even in the late 19th century: “there are two things after death: putrefaction, the work of microbes, and disappearance, the work of insects.” -Yovanovitch (1888)
Our work, as previously described, is focused on conducting empirical studies for testing hypotheses and ecological theory of insect-microbe interactions across complex and dynamic habitats. The resulting frameworks, protocols, models, and theories will be informative to improving knowledge in basic decomposition ecology. Further, these data have potential to become a powerful tool in applications, such as forensics, when law enforcement agencies are investigating the circumstances of death.