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Interpreting Beta Diversity Over Time: An Assessment of Local- and Broad-Scale Patterns in Arthropod Communities

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Title: Interpreting Beta Diversity Over Time: An Assessment of Local- and Broad-Scale Patterns in Arthropod Communities
Author: D'Souza, Michelle
Department: Department of Integrative Biology
Program: Integrative Biology
Advisor: Hebert, Paul
Abstract: Beta diversity, the component of regional diversity that reflects compositional heterogeneity among biological communities, is used to refer to numerous phenomena and is often misinterpreted and misapplied. Past studies have examined beta diversity from a spatial perspective but relatively little is known about beta diversity over time. This gap needs to be addressed because understanding of beta diversity can provide valuable insights into the processes that promote and sustain regional diversity. In this thesis, I explore the evolution of the beta diversity concept, evaluate the state of prior studies, and contribute novel data to address the gap in temporal analyses. First, with evidence from the tropical arthropod literature, I argue that confusion of the beta diversity concept, along with a lack of standardized methods of species identification and data accessibility, impede our capacity to discern broad-scale patterns. Recent theoretical and mathematical treatments of the beta diversity concept, along with DNA-based approaches for species identification and data preservation, provide new tools to tackle impediments in the detection of patterns. I demonstrate their utility through the spatio-temporal analyses of arthropod communities on a local scale in a tropical montane forest in Honduras, and on a broad scale at 20 sites spanning a 100° latitudinal gradient. Results indicate that while spatial gradients underlie high beta diversity in tropical arthropod communities, change in temporal turnover fluctuates, affecting beta diversity detected at the local scale. But patterns suggest that the baseline level of turnover is stable and that arthropod taxa partition into two groups by their temporal occupancy in the community, differing in their contribution to that stability over time. Broad-scale patterns further highlight the importance of considering time as increase in the non-random distribution of species over a year at high latitudes obscured the latitudinal gradient in beta diversity over time. This gradient was associated with latitudinal differences in the species abundance distribution suggesting similar underlying community assembly mechanisms. This thesis has advanced understanding of beta diversity by highlighting limitations in current data on arthropod communities and by demonstrating the importance of including its temporal dimension in considerations of both local- and broad-scale patterns.
URI: http://hdl.handle.net/10214/12945
Date: 2018-04
Rights: Attribution-NonCommercial-NoDerivs 2.5 Canada
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