The Pennsylvania State University The Graduate School MORPHOLOGICAL CHANGE IN RESPONSE TO MASS EXTINCTION: A CASE STUDY OF STROPHOMENIDA (BRACHIOPODA) AT THE LATE ORDOVICIAN A Dissertation in Geosciences by Judith A. Sclafani Ó 2019 Judith A. Sclafani Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy December 2019 The dissertation of Judith A. Sclafani was reviewed and approved* by the following: Mark E. Patzkowsky Professor of Geosciences Associate Department Head of Graduate Programs Dissertation Advisor Chair of Committee Peter Wilf Professor of Geosciences Timothy J. Bralower Professor of Geosciences David P. Hughes Associate Professor of Entomology and Biology *Signatures are on file in the Graduate School iii ABSTRACT There have been five mass extinctions throughout the Phanerozoic, all of which were caused by catastrophic disruptions to the earth system and resulted in significant biotic upheaval. Anthropogenic climate change, combined with other human activities, is pushing Earth towards a possible sixth mass extinction. The fossil record of extinctions contains clues about what might happen to Earth’s biota in the near future. I focus on the Late Ordovician mass extinction, which is the first of the “big 5” mass extinctions and the second largest. It was caused by a rapid climate event that resulted in the growth of continental glaciers and a drop in sea level. The ecological effect of this extinction is less than might be expected given the amount of taxonomic loss. Studying the nuances of this pattern from an evolutionary and ecological perspective might yield insight into some of the more complex metrics of quantifying changing biodiversity. To achieve this, I quantify morphology of the brachiopod order Strophomenida. Morphology is a product of evolution and ecology, allowing for the analysis of both. Results indicate a morphologic bottleneck at the Late Ordovician mass extinction event. This observed restriction in morphologic variability occurs within one clade that originates during the Silurian recovery interval. Further exploration of the data indicates no clear ecological signature to the bottleneck. The complex relationship between ecology and evolutionary history highlights the need to employ both approaches to develop a more complete understanding of intervals of biotic change. iv TABLE OF CONTENTS LIST OF FIGURES ...................................................................................................................... vi LIST OF TABLES ........................................................................................................................ ix ACKNOWLEDGEMENTS ........................................................................................................... x INTRODUCTION .......................................................................................................................... 1 THE LATE ORDOVICIAN MASS EXTINCTION ................................................................... 2 SUMMARY OF MAJOR FINDINGS ...................................................................................... 4 Chapter 1 ................................................................................................................................... 4 Chapter 2 ................................................................................................................................... 5 Chapter 3 ................................................................................................................................... 6 CHAPTER 1 EFFECTS OF MASS EXTINCTION AND RECOVERY DYNAMICS ON LONG-TERM EVOLUTIONARY TRENDS: A MORPHOLOGICAL STUDY OF STROPHOMENIDA (BRACHIOPODA) ACROSS THE LATE ORDOVICIAN MASS EXTINCTION ................................................................................................................................ 8 ABSTRACT ....................................................................................................................... 9 INTRODUCTION .............................................................................................................. 10 BACKGROUND ............................................................................................................... 12 Late Ordovician mass extinction and recovery ...................................................................... 12 Strophomenida ........................................................................................................................ 15 Models for morphological change in the extinction and recovery ......................................... 16 METHODS ...................................................................................................................... 17 Ancestral state reconstruction ................................................................................................. 17 Morphospace ........................................................................................................................... 19 Potential sampling and biogeographic biases ......................................................................... 21 Bootstrap analysis of extinction and recovery ........................................................................ 22 RESULTS ........................................................................................................................ 23 Morphospace occupation through time .................................................................................. 23 Are extinction and origination random? ................................................................................. 26 DISCUSSION ................................................................................................................... 28 Impact of the Late Ordovician mass extinction ...................................................................... 28 The importance of the Silurian recovery ................................................................................ 30 The effect on long-term clade trajectory ................................................................................ 31 CONCLUSION ................................................................................................................. 33 ACKNOWLEDGMENTS .................................................................................................... 34 LITERATURE CITED ....................................................................................................... 34 CHAPTER 2 HOW SIMILAR ARE SISTERS? THE RELATIONSHIP BETWEEN MORPHOLOGY, ECOLOGY, AND EVOLUTIONARY HISTORY ................................... 50 ABSTRACT ..................................................................................................................... 51 INTRODUCTION .............................................................................................................. 52 BACKGROUND ............................................................................................................... 54 The phylogenetic distance/ecological difference hypothesis ................................................. 54 Community Assembly ............................................................................................................ 56 Expectations for the fossil record ........................................................................................... 58 Expectations for Strophomenida ............................................................................................. 60 METHODS ...................................................................................................................... 61 v Phylogenetic data .................................................................................................................... 61 Morphological data ................................................................................................................. 62 Ecological data ........................................................................................................................ 63 RESULTS ........................................................................................................................ 65 Environmental affinities ......................................................................................................... 65 PDED in the order-scale phylogeny ....................................................................................... 67 PDED in the recovery clade phylogeny .................................................................................. 67 DISCUSSION ................................................................................................................... 68 The evolution of ecologies during radiations ......................................................................... 70 Metacommunity theory and hierarchical scaling in paleoecology ......................................... 71 CONCLUSIONS ............................................................................................................... 73 REFERENCES .................................................................................................................. 74 CHAPTER 3 ECOLOGICAL SELECTIVITY OF STROPHOMENIDA (BRACHIOPODA) DURING AND AFTER THE LATE ORDOVICIAN MASS EXTINCTION .............................................................................................................................. 93 ABSTRACT ....................................................................................................................