Dissertation/Thesis Abstract

Ecological, Taphonomic, and Paleoecological Dynamics of an Ostracode Metacommunity
by Michelson, Andrew V., Ph.D., The University of Akron, 2012, 503; 10631180
Abstract (Summary)

The modern synthesis of paleontology with evolutionary biology has successfully integrated population ecology into the study of the fossil record. While it may prove impossible to measure and account for the important processes that structure communities through time, the integration of community ecology into paleoecology remains to be done to further the modern synthesis. This dissertation attempts to integrate community ecology into the study of a lacustrine ostracode metacommunity across space today and through the mid Holocene on San Salvador Island, Bahamas.

Patterns of community change across space today are investigated by comparing the live/dead agreement in taxonomic composition and rank-abundance of species in seven lakes. This taphonomic study establishes that live/dead agreement of ostracode assemblages is high in all lakes save one. Therefore, sampling of death assemblages, as is common in many paleolimnolgical studies, can be used to investigate changes in alpha and beta diversity of assemblages across time and space.

Death assemblages were then sampled from thirty-two lakes on San Salvador to investigate the metacommunity dynamics that explain patterns of beta diversity of communities. I found that beta diversity was most strongly controlled by the local environment in which communities live with the change in communities most strongly correlated with changes in a complex hydrological gradient of: conductivity, dissolved oxygen, and alkalinity.

After establishing that the metacommunity dynamics conformed to a species sorting model, I exploited the association between ostracode assemblages and conductivity to create a statistical model that used changes in ostracode assemblages to predict changes in conductivity within individual lakes on San Salvador. This model was then applied to archives of ostracode assemblages from the mid-Holocene to today to create a record of changing conductivity through time in three lakes. The model reveals large, high-frequency fluctuations in conductivity controlled by regional changes in precipitation/evaporation ratios, controlled by similarly high frequency climate oscillations.

Finally, I use the metacommunity concept of community ecology as a theoretical tool to explain how changes in communities through time are related to ecosystem dynamics. Ostracodes, as easily-dispersed organisms who respond to changes in their local environment through habitat-tracking, prove to be consistently useful proxies of environmental changes. In this way, neontological principles are successfully applied to the paleoecological record demonstrating the seamless application of community ecology to the fossil record.

Indexing (document details)
Advisor: Park, Lisa E.
Commitee: Moore, Francisco B.-G., Pan, Jean J., Senko, John M., Smith, Alison J.
School: The University of Akron
Department: Integrated Bioscience
School Location: United States -- Ohio
Source: DAI-B 78/11(E), Dissertation Abstracts International
Subjects: Paleoecology
Keywords: Bahamas, ENSO, Metacommunity, Ostracode, San Salvador Island, Taphonomy, Transfer function
Publication Number: 10631180
ISBN: 9780355014617