EVOLUTIONARY TRENDS OF THE CARBONIFEROUS OSTRACOD VELATOMORPHA ALTILIS, JOGGINS FOSSIL CLIFFS, UNESCO WORLD HERITAGE SITE by Regan Maloney Thesis submitted in partial fulfillment of the requirements for the Degree of Bachelor of Science with Honours in Biology Acadia University April, 2016 © Copyright by Regan Maloney, 2016 This thesis by Regan Maloney is accepted in its present form by the Department of Biology as satisfying the thesis requirements for the degree of Bachelor of Science with Honours Approved by the Thesis Supervisor __________________________ ____________________ Peir Pufahl Date Approved by the Head of the Department __________________________ ____________________ Brian Wilson Date Approved by the Honours Committee __________________________ ____________________ Anna Redden Date ii I, Regan Maloney, grant permission to the University Librarian at Acadia University to reproduce, loan or distribute copies of my thesis in microform, paper or electronic formats on a non-profit basis. I, however, retain the copyright in my thesis. _________________________________ Regan Maloney _________________________________ Date iii Acknowledgements I received a lot of support while writing this thesis. Neil Tibert was instrumental to this project. He guided me with enthusiasm in the early stages. His passing is a loss well beyond his research. He always had time for my questions and his excitement about ostracods and life was infectious. Melissa Grey and Peir Pufahl were always encouraging along way and helped me a great deal. This project was made possible with a NSERC USRA grant. iv Table of Contents Acknowledgements ......................................................................................................................... iv List of Tables .................................................................................................................................. vi List of Figures ................................................................................................................................ vii Abstract ......................................................................................................................................... viii 1. Introduction .......................................................................................................................... 1 1.1 Study site .......................................................................................................................... 1 1.2 Facies Associations .......................................................................................................... 2 1.3 Limestone Lithofacies ...................................................................................................... 3 1.4 Ostracods ......................................................................................................................... 7 1.5 Evolutionary Modes ......................................................................................................... 9 1.6 Purpose ........................................................................................................................... 11 2. Materials and Methods ........................................................................................................... 12 2.1 Extraction ....................................................................................................................... 12 2.2 Measurement .................................................................................................................. 15 2.3 Multivariate Analysis ..................................................................................................... 17 2.4 Evolutionary Mode ........................................................................................................ 17 2.5 Abundance and population structure.............................................................................. 18 3. Results .................................................................................................................................... 20 3.1 Multivariate analysis ...................................................................................................... 20 2.2 Evolutionary Mode .............................................................................................................. 23 3.3 Thin Sections ....................................................................................................................... 24 4. Discussion .................................................................................................................................. 29 4.1 Evolutionary Mode ........................................................................................................ 29 4.2 Population Structure and Environmental Interpretations ............................................... 33 5. Conclusions ................................................................................................................................ 35 References ...................................................................................................................................... 36 Appendix ........................................................................................................................................ 39 v List of Tables Table 1. Location of limestones used for ostracod sampling and thin sectionanalysis…………19 Table 2. Confusion matrix derived from the CVA……………………………………………… 22 Table 3. Results of Hunt’s (2008) “fit 3 models” tests.................................................................. 24 Table 4. Results of thin section analysis. ...................................................................................... 25 Table 5. Akaike and AICC of Hunt’s (2008) “fit 3 models”.......................................................... 39 vi List of Figures Figure 1. Dark, organic rich limestone beach outcrop at the Joggins Fossil Cliffs site (Aziz, 2010).Figure 1 .................................................................................................................................. 5 Figure 2. Wave rippled limestone outcrop on beach at the Joggins Fossil Cliffs site (Aziz, 2010).Figure 2 .................................................................................................................................. 6 Figure 3. Location of the Joggins Fossil Cliffs UNESCO World Heritage Site on the Bay of Fundy, in the Cumberland Basin (blue star).Figure 3 .................................................................... 13 Figure 4. Stratigraphic column of formations at the Joggins Fossil Cliffs ................................... 14 Figure 5. Example of V.altilis in left lateral view. ........................................................................ 16 Figure 6. Example of V.altilis in dorsal view. .............................................................................. 16 Figure 7. Principal component analysis results ............................................................................. 20 Figure 8. Canonical variate analysis results .................................................................................. 21 Figure 9. Example of a thin section from Boss Point 2 ................................................................ 26 Figure 10. Joggins Formation thin section (Joggins 4t) ................................................................ 27 Figure 11. Thin section from the Joggins 5T (Table 1) limestone ................................................ 28 vii Abstract The ostracod Velatomorpha altilis thrived in brackish coastal environments of the Carboniferous. Especially well preserved examples occur in strata exposed at the Joggins Fossil Cliffs World Heritage Site, Cumberland Basin, Nova Scotia, providing an opportunity to investigate the link between evolutionary mode and temporal changes in depositional environment. The relationship between the evolutionary mode of V. altilis and its environment is especially important because few other studies have examined the evolutionary mode of organisms living in marginal environments. The evolutionary mode of V. altilis was analyzed by measuring the length, height, width, area, and perimeter of valves from 332 specimens from limestone at five stratigraphic levels in the Boss Point and overlying Joggins formations. Interpretations of depositional environment in this study were based in part on ostracod population structure with no statistical treatment of the data. After quantitative model-based analysis, an unbiased random walk was supported as the evolutionary mode when ostracods from all five stratigraphic levels were included. Stasis was the suggested evolutionary mode only when ostracods from each formation were considered separately. This is consistent with previous research on V. altilis from the Joggins Formation. Stasis is expected in fluctuating, stressed environments, such as the brackish coastal paleoenvironments of the Boss Point and Joggins formations. This is because organisms that inhabit those environments are usually tolerant to changing conditions. It is possible that between the formations an environmental threshold was reached that triggered rapid change in shell size. Ostracod population structure analysis supports this interpretation and suggests shell size may record a difference in hydrologic regime of limestone between the Boss Point and viii Joggins formations. This represents a classic example of punctuated equilibrium model of evolutionary