SPECIES ASSEMBLAGE STRUCTURE AND ECOMORPHOLOGICAL CONVERGENCE IN PERCIFORM FISHES (CICHLIDAE AND CENTRARCHIDAE) IN TROPICAL AND TEMPERATE FLOODPLAIN RIVERS A Dissertation by CARMEN GRAVIELA MONTAÑA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Chair of Committee, Kirk O. Winemiller Committee Members, Gil G. Rosenthal Stephen E. Davis Luis Hurtado Head of Department, Michael Masser December 2012 Major Subject: Wildlife and Fisheries Sciences Copyright 2012 Carmen Graviela Montaña ABSTRACT In this study, I used two independent perciform lineages (Neotropical Cichlidae and Nearctic Centrarchidae) to examine patterns of species richness and species coexistence at two spatial scales (e.g., macrohabitat and mesohabitat) and to examine inter-faunal patterns of ecomorphological convergence. The study was conducted during the low-water periods in four lowland rivers: the Cinaruco in Venezuela, the Tambopata in Peru, and the Neches and the Brazos rivers in Texas (USA). These rivers were chosen because of their similar characteristics, in terms of geomorphology, sediments, and water quality. The Cinaruco River and the Neches River have clear slightly-stained waters, whereas the Tambopata and the Brazos River have turbid waters with high loads of suspended sediments. I used morphological approaches as a surrogate to investigate patterns of species distribution in niche space, and predict patterns of species richness at different spatial scales. Despite high variation in the number of species in these two perciform assemblages, morphological analysis based on the means and standard deviations of nearest neighbor distance (NND) and mean distance to centroid (CD) revealed similar trends of morphological similarity in relation to species richness. Comparison of observed versus randomized data mesohabitat scale for all four rivers generally supported the niche expansion model of response to increase in species richness. At the scale of mesohabitats within rivers, most species assemblages appear to be organized by competitive interactions in accordance with the niche expansion model. The tropical species-rich Cinaruco River revealed particularly strong support for the ii niche expansion model. Intercontinental comparison of functional morphology and diets based on analysis of stomach contents and stable isotope ratios indicated broad morphological and dietary overlap between cichlid and centrarchid assemblages. For the most part, morphological ordinations showed that the two groups have diversified in a parallel manner within the confines of ram-suction modes of prey ingestion. This study concludes that even though differences are observed in historical and stochastic factors structuring fish assemblages in different geographic regions, consistent patterns of convergence at the species and assemblage levels results from natural selection under similar environmental conditions. iii DEDICATION To my family To Donald Charles Taphorn iv ACKNOWLEDGEMENTS During my time as a graduate student, many individuals and organizations have provided inspirational, logistic, or personal support in order to aid my research progress and completion. Funding for the cichlid project was provided through a NSF grant to Kirk O. Winemiller, Hernán López-Fernández, and Rodney Honeycutt (DEB 0516831), and the American Cichlid Association (Loiselle Conservation Grant). Funding for the centrarchids project was provided by Carolyn Wierichs Kelso and George Kelso via the International Sportfish Fund and by the Clark Hubbs Student Award. I was supported as a Tom Slick Graduate Research Fellowship at Texas A&M University during the last year of my dissertation. I owe my thanks to my supervisor Dr. Kirk O. Winemiller for letting me come to his lab, to share with me his scientific guidance and the passion for science and fishes. Thanks for being an excellent supervisor! Not only for constructive criticisms to my manuscripts, but also for being patient during my graduate student process. Thanks much Kirk for including me in expeditions to Cambodia and Guyana! These were incredible experiences that will keep in my memories forever. I cannot imagine all this time as a graduate student without Don Taphorn’s friendship and guidance. Thank you Don for being part of this experience, for opening the door to study fishes, for giving me the opportunity to work with you, also for having time to listen to, and discuss with me ideas about fishes. Thanks much for always being there as a good father! v I thank my dissertation committee: Drs. Luis Hurtado, Steve Davis, and Gil Rosenthal for their time and individual attention when I needed it. Thanks to Dr. Kevin Conway for his friendship, his comments on fishes, and for the fish drawings. I am especially grateful to my colleague and friend Craig Layman. Craig started it all when I worked with him in the museum in Guanare and then in the Cinaruco River. Working with him was a tremendous opportunity that turned into research, publications, and getting involved with the Winemiller lab. I benefited enormously from the time I spent working with Craig in Venezuela and later at Yale University and Florida International University. I recognize the friendship, intellectual contribution, and field assistance of my lab mates: Katie Roach, Andrew Jackson, Chouly Ou, Liz Carrera, Chevaun McCray, Crystal Watkins, Dan Fitzgerald, Bibiana Correa, the former lab mates Allison Pease and Nathan Lujan. Each aided me in one way or another during my life as a graduate student. I also thank undergrads from WFSC, Matthew Acre and Zach Peterson for their tremendous help in the field during the summer 2009 and 2010, and Jill Sechelski and Monika Libson for the great work dissecting sunfishes. I also thank my friends from Wildlife and Fisheries who provided emotional support and advise when needed. In particular I would like to thank the Fitzgerald lab (Christopher M. Schalk, Nicole Smolensky, Dan Leavitt, and Mike Treglia) and Mateos and Hurtado lab (Maura Palacios, Eun Lee, Shuang Liu). My research in Venezuela was carried out thanks to amazing people and lab technician in the Museo de Ciencias Naturales Guanare. I would like to thank the vi valuable help I received in the field from Alexis Medina, Pablo Medina, Wilson Garcia, Jose Garcia, Nola Garcia and Yarisma Garcia. Fishing permits in Venezuela were granted by the Instituto Nacional Autonomo de Pesca and Acuicultura. Finally, I want to especially thank those people who in one way or another assisted me in this journey. Christopher M. Schalk has lot of patience and motivation and provided me with companionship. Chris provided consistent advice and support during the final year of my dissertation. My parents, brothers, and sisters managed to stay close despite the great distance. I thank Elina Pérez, Crispulo Marrero, and Maria Alejandra Pérez for their friendship and having treated me like family. Thanks much! vii TABLE OF CONTENTS Page ABSTRACT .............................................................................................................. ii DEDICATION .......................................................................................................... iv ACKNOWLEDGEMENTS ...................................................................................... v TABLE OF CONTENTS .......................................................................................... viii LIST OF FIGURES ................................................................................................... x LIST OF TABLES .................................................................................................... xii CHAPTER I INTRODUCTION: MORPHOLOGICAL AND ECOLOGICAL CONVERGENCE IN NEOTROPICAL CICHLIDS AND NEARCTIC CENTRARCHIDS .................................................................................................... 1 CHAPTER II LOCAL-SPECIES DIVERSITY IN NEOTROPICAL AND TEMPERATE FLOODPLAIN RIVERS: A MORPHOLOGICAL APPROACH... 6 Introduction ....................................................................................... 6 Material and Methods ........................................................................ 11 Results ............................................................................................... 20 Discussion ......................................................................................... 36 CHAPTER III ECOMORPHOLOGICAL CONVERGENCE IN NEOTROPICAL CICHLIDS AND NEARCTIC CENTRARCHIDS: EVIDENCE FROM MORPHOLOGY, DIET AND STABLE ISOTOPE ANALYSIS……. ...... 43 Introduction ...................................................................................... 43 Materials and Methods .................................................................... 47 Results ............................................................................................. 57 Discussion ....................................................................................... 73 CHAPTER IV CONCLUSIONS ............................................................................. 80 General Conclusions ......................................................................... 80 viii Page LITERATURE CITED ............................................................................................. 84 APPENDIX A ........................................................................................................... 102 APPENDIX B ..........................................................................................................