Doctoral Dissertations

Date of Award

12-2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Plant, Soil and Environmental Sciences

Major Professor

Jennifer DeBruyn

Committee Members

Michael Essington, Ernest C. Bernard, Dawnie Steadman

Abstract

The effects of vertebrate decomposition are wide-ranging across multiple foodwebs, and have been shown to persist in the environment, however there is a lack of systematic assessment of these changes over long periods of time or in sufficiently high resolution as to resolve seasonal flux patterns. The ultimate aim of this body of research was to explore nematode systematics in decomposition environments, culminating in a pair of long-term human decomposition seasonal trials, in high resolution, with the specific intent of integrating the fields of soil chemistry, microbial ecology, and nematology in order to assess the relationships of cross-disciplinary impacts. Of these three fields, soil chemistry has the largest body of literature dedicated to its study. Microbial ecology, for forensic purposes, is still an emerging field, and primarily focuses on bacterial successional characteristics in the early phases of decomposition. Nematology as a forensic tool has had very little study dedicated to it, however initial results are promising. Therefore, prior to performing a fully integrated study, further examination of nematode community systematics was required in order to ascertain the nature of their responses to the decomposition environment. Our body of work consisted of three objectives: (1) evaluation of nematode communities in a multi-individual grave, (2) evaluation of longitudinal patterns in nematode diversity in an animal model system, and (3) evaluation of seasonal differences in decomposition patterns across the disciplines of soil chemistry, microbial ecology, and nematology, in high resolution and long-term. Overall, nematode communities were shown to exhibit persistent modification after four years in a grave, and successional patterns in a vertebrate surface-decomposition model system. The human seasonal study demonstrated that soil chemistry and fungal beta diversity were inextricably interlinked, as were nematode abundances and thermal effects, and that seasonal rates of change in decomposition progression are mirrored across all three disciplines. This suite of simultaneous changes is sufficiently compelling for us to recommend that it is absolutely crucial to broaden decomposition soil research into an interdisciplinary study in order to fully and accurately contextualize these processes in future work.

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