Is Diet Correlated with Feeding Morphology in Neotropical Suckermouth Armoured Catfishes (Siluriformes: Loricariidae)? by Stéphanie L. Lefebvre A thesis submitted in conformity with the requirements for the degree of Masters of Science Ecology and Evolutionary Biology University of Toronto © Copyright by Stephanie L. Lefebvre 2014 Is Diet Correlated with Feeding Morphology in Neotropical Suckermouth Armoured Catfishes (Siluriformes: Loricariidae)? Stéphanie L. Lefebvre Masters of Science Ecology and Evolutionary Biology University of Toronto 2014 Abstract The suckermouth armoured catfishes (Siluriformes: Loricariidae) are a diverse group of predominantly detritivorous fishes inhabiting rivers of South and Central America. Their distinct jaws are specialized for scraping a wide range of substrate. Though it is hypothesized that specialization of loricariid feeding morphology may have played a role in their diversification, little is known about the ecological and evolutionary processes involved. The present study quantifies variation in jaw functional traits and body morphology in a phylogenetic context. Morphological variation was compared to species’ relative position in assemblage isotope space (for both δ13C and δ15N) to test for correlations between diet and feeding morphology. Results show that although jaw functional traits are decoupled from body morphology, both are correlated with δ13C values. Partitioning of terrestrial and aquatic resources can be explained by both jaw functional traits and body morphology, however further partitioning of diet is only attributed to the former. ii Acknowledgements I would like to thank Nathan K. Lujan for providing isotope and jaw data, along with a wealth of information about loricariids, and for organizing the provision of specimens from both the Auburn University Museum Fish Collection (AUM) and the Academy of Natural Sciences of Philadelphia (ANSP). I am deeply grateful to my supervisors, Hernán López-Fernández and Nathan Lovejoy, for guidance, insight, and funding. My supervisory committee members, Jason Weir and Don Jackson, for helpful discussion and guidance. The curators of the fish collections at their respective institutions for allowing me to dissect their specimens – Jon Armbruster (AUM), Mark Sabaj Pérez (ANSP), and Hernán López-Fernández (ROM). I am indebted to Sarah Steele for being a great sounding board to my crazy ideas, for providing the outline to Figure 4 (Methods, section 1.2.6), and for always being there for support. Finally, I’d like to thank the López-Fernández lab members for all the discussions, insight, R code help, and laughs along the way. You guys are awesome. iii Table of Contents Acknowledgements ........................................................................................................................ iii Table of Contents ........................................................................................................................... iv List of Tables ................................................................................................................................. vi List of Figures ............................................................................................................................... vii List of Appendices ....................................................................................................................... viii 1.1 Introduction ......................................................................................................................... 1 1.2 Methods ............................................................................................................................... 4 1.2.1 Samples ................................................................................................................... 4 1.2.2 Jaw Dissection and Preparation .............................................................................. 4 1.2.3 Imaging ................................................................................................................... 5 1.2.4 Jaw Parameters ........................................................................................................ 6 1.2.5 Jaw Functional Traits .............................................................................................. 7 1.2.6 Body Morphology ................................................................................................... 8 1.2.7 Phylogenetic Corrections ...................................................................................... 10 1.2.8 Diet Information .................................................................................................... 12 1.2.8.1 Diet Categories ....................................................................................... 12 1.2.8.2 Stable Isotope Analysis .......................................................................... 13 1.3 Results ............................................................................................................................... 14 1.3.1 Significant Principal Components Test ................................................................ 14 1.3.2 Jaw Functional Traits Analyses ............................................................................ 15 1.3.3 Body Morphology Analysis .................................................................................. 18 1.3.4 Diet-Morphology Correlations .............................................................................. 21 iv 1.4 Discussion ......................................................................................................................... 23 1.4.1 Jaw Functional Traits Analyses ............................................................................ 23 1.4.2 Body Morphology Analysis .................................................................................. 24 1.4.3 Diet Groups ........................................................................................................... 24 1.4.3.1 Algae Scrapers (Gray) ............................................................................ 24 1.4.3.2 Wood-Eaters (Purple) ............................................................................. 25 1.4.3.3 Insect and Mollusk Eaters (Pink) ........................................................... 26 1.4.3.4 Aufwuch Eaters (Yellow) ....................................................................... 27 1.4.4 Habitat Use ............................................................................................................ 28 1.4.5 Diet-Morphology Correlations .............................................................................. 29 13 1.4.5.1 Relationship Between δ C and Jaw Functional Traits .......................... 29 13 1.4.5.2 Relationship Between δ C and Body Morphology ............................... 30 1.4.5.3 Implications of Diet-Morphology Correlations in Loricariids ............... 30 1.5 Conclusions ....................................................................................................................... 31 References ..................................................................................................................................... 33 Appendix A ................................................................................................................................... 39 Appendix B ................................................................................................................................... 45 v List of Tables Table 1. Parameters quantifying morphological variation in loricariid mandibles ........................ 6 Table 2. Morphological variables used to quantify aspects of body size and shape in loricariids. 9 Table 3. Diet information identified for a subset of loricariids in this study, based on references to diet in literature. ........................................................................................................................ 12 Table 4. Species abbreviations used in all analyses.. .................................................................... 15 Table 5. Principal components analysis eigenvectors for jaw functional traits and body morphology.. ................................................................................................................................. 16 Table 6. Results of PGLS regressions using centroid deviations of δ13C and δ15N against residuals of the first two principal components of the jaw functional traits (f) and body morphology (b) . ........................................................................................................................... 21 vi List of Figures Figure 1. Representative sample of lower jaws from Loricariidae examined in this study showcasing morphological diversity in the family. ........................................................................ 2 Figure 2. Orientation of lower jaw ramus of Hypostomus hemiurus.. ............................................ 5 Figure 3. Mandible of Hypostomus macushi illustrating parameters used in this study, as defined in Table 1. .................................................................................................................................... 7 Figure 4. Visual representation of body measurements used to evaluate size and shape differences in the present study.. ................................................................................................... 10 Figure 5. Multi-locus molecular phylogeny of a subset