Dissertation/Thesis Abstract

The Role of Scale in Ecological Inference: Implications for Interpreting Hominin Paleoecology
by Du, Andrew, Ph.D., The George Washington University, 2017, 221; 10252703
Abstract (Summary)

Modern and fossil ecological data exist at very different taxonomic, spatial, and temporal scales. For modern ecology, data are typically collected at the species-level, cover square meter quadrats to the entire globe, and span days to decades at most. For fossil assemblages, spatial scale might be comparable to that studied by modern ecologists, but fossil data are taxonomically and temporally much coarser (respectively, order-, family-, genus-level at best, and 104-108 years). Recent research has shown that ecological patterns and the processes affecting them change across scale. Therefore, using modern ecological theory and methods to study fossil data is an incommensurate exercise and potentially produces spurious results. Moreover, scale varies by orders of magnitude even among fossil assemblages, so comparing fossil sites without an appreciation of scale may also lead to ambiguous conclusions.

I argue that a disregard of scale within paleoanthropology has contributed to its inability to synthesize seemingly disparate paleoecological results into a coherent, unified framework. As a result, paleoanthropology has remained relatively stagnant regarding its understanding of how paleoecological processes drove hominin evolution. With this in mind, I adopt scale as a central theme in my dissertation and attempt to understand how ecological pattern and process change across modern and fossil scales in East African large mammal communities, and if these scale differences can be analytically reconciled.

The results from my three research chapters show ecological patterns (and the relevant processes driving them) fundamentally change across modern and fossil scales. Thus, modern and paleoecological theory and data are each incomplete: modern ecologists need to analyze fossil data if they want to study ecology at large time scales, and paleoecologists need to examine modern data and theory in order to understand smaller-scale processes; simple extrapolation and interpolation will not do. For paleoanthropologists, that means it is less than straightforward to infer smaller-scale ecological processes (e.g., paleoenvironmental reconstruction, interspecific interactions) from fossil assemblages, and caution should be exercised when attempting to do so. I by no means offer a panacea for this scale issue, but hopefully my research will make paleoanthropologists more cognizant of scale and encourage future research on this topic. Only then can we finally begin to understand what exactly were the important ecological drivers affecting hominin behavior and evolution.

Indexing (document details)
Advisor: Behrensmeyer, Anna K., Wood, Bernard A.
Commitee: Bobe, Rene, Lyons, Sara K., McGill, Brian J.
School: The George Washington University
Department: Hominid Paleobiology
School Location: United States -- District of Columbia
Source: DAI-B 78/06(E), Dissertation Abstracts International
Subjects: Physical anthropology, Macroecology, Paleoecology
Keywords: Core-transient paradigm, Species pool, Species turnover, Species-time-area relationship
Publication Number: 10252703
ISBN: 978-1-369-53027-8
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