Western University Scholarship@Western Electronic Thesis and Dissertation Repository 12-13-2013 12:00 AM Foraging ecology, sexual selection, and divergence in sunfish (Lepomis spp.) Scott F. Colborne The University of Western Ontario Supervisor Bryan Neff The University of Western Ontario Graduate Program in Biology A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Scott F. Colborne 2013 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Biology Commons Recommended Citation Colborne, Scott F., "Foraging ecology, sexual selection, and divergence in sunfish (Lepomis spp.)" (2013). Electronic Thesis and Dissertation Repository. 1764. https://ir.lib.uwo.ca/etd/1764 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. FORAGING ECOLOGY, SEXUAL SELECTION AND DIVERGENCE IN SUNFISH (LEPOMIS SPP.) (Thesis format: Integrated Article) by Scott Fitzgerald Colborne Graduate Program in Biology A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy The School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario, Canada © Scott Fitzgerald Colborne 2013 Abstract The origins of novel traits and their contribution to biodiversity have long been of interest to biologists. My research focused on the links between foraging ecology and both natural and sexual selection, and how these mechanisms interact to shape the phenotypic diversification of natural populations. Using bluegill (Lepomis macrochirus) and pumpkinseed sunfish (L. gibbosus), I examined three major questions: 1) how are diet and morphological variation related to alternative reproductive tactics in bluegill; 2) are sexual selection and disruptive selection driving divergence between foraging ecomorphs in pumpkinseed; and 3) how are human-induced changes to prey communities affecting foraging ecology of pumpkinseed. By examining the alternative reproductive tactics of bluegill, I found that the deeper bodied parental males and females consumed more zooplankton as compared to the littoral diets of the more streamlined sneakers, satellites, and juveniles, the opposite relationship from what is typically observed in fish. However, the morphological and swim performance variation among reproductive groups may increase mating success, indicating that sexual selection may be an important factor in the phenotypic diversification of bluegill. I next examined the relationship between stable isotopes (δ13C and δ15N) in different female tissues (white muscle, liver, and eggs), and found that from pre-fertilization to the day of hatch eggs could be used as a proxy for female diet. By collecting nest guarding males and eggs from their nests it is possible to estimate assortative mating based on foraging tactic. Applying this technique to a wild population of pumpkinseed, I found evidence of phenotypic divergence and assortative mating between foraging tactics. However, there was no evidence of neutral genetic divergence, possibly related to strength of disruptive selection, gen flow by ii cuckolders, or selection on functional loci. Finally, I found that native pumpkinseed sunfish in three populations have undergone substantial shifts in diet following the invasion of zebra mussels (Dreissena polymorpha), consuming considerably more zebra mussels and fewer benthic invertebrates than before the invasion. These results contribute to a growing body of evidence that foraging ecology and its relationships with both disruptive natural and sexual selection play a key role in the evolution and diversification of natural populations. Keywords Assortative mating, disruptive selection, ecomorphology, evolution, foraging ecology, invasive species, morphology, sexual selection, stable isotopes, sunfish, swim performance, sympatric speciation iii Co-Authorship Statement A version of Chapter 2 was published in the Canadian Journal of Fisheries and Aquatic Sciences (68: 1802-1810, 2011) with Marie-Christine Bellemare, Pedro Peres-Neto, and Bryan Neff as co-authors (see Appendix E for permission to reproduce material). Funding for this project was received from both B.D. Neff and P.R. Peres-Neto. M.C. Bellemare contributed to fish collections and swim performance measurements. All co-authors contributed to experimental design, sampling, and contributed editorial comments to the manuscript. S.F. Colborne was responsible for sampling protocol, fish collection, data analysis and served as the primary author of this publication. A version of Chapter 3 was published in the journal Behavioral Ecology (24:1339-1347, 2013) with Pedro Peres-Neto, Fred Longstaffe, and Bryan Neff as co-authors (see Appendix E for permission to reproduce material). Funding for the project was received by grants to B.D. Neff, P.R. Peres-Neto, F.J. Longstaffe, and S.F. Colborne (see chapter acknowledgements for details of funding sources to each individual). B.D. Neff and P.R. Peres-Neto contributed to the experimental design and editorial comments. F.J. Longstaffe contributed to sample analysis as part of a collaboration with the Laboratory for Stable Isotope Science (LSIS) at The University of Western Ontario, as well as data analysis, and provided editorial comments. S.F. Colborne was the individual primarily responsible for experimental design, sample collection, analysis, and preparation of written materials. A version of Chapter 4 was submitted to the Canadian Journal of Fisheries and Aquatic Sciences (under review) with T.J.A. Hain, F.J. Longstaffe, and B.D. Neff as co-authors. Funding for this project was received through grants to B.D. Neff, P.R., Peres-Neto, and S.F. Colborne (see chapter for funding source details). T.J.A. Hain contributed to the iv experimental design, experimental crossing of fish, and editorial comments on the manuscript. F.J. Longstaffe contributed to data analysis and provided editorial comments as part of a collaborative project with the LSIS research group (see chapter 3 above). B.D. Neff contributed to the experimental design and editorial comments of the manuscript. Chapter 5 was completed in collaboration with S.R. Garner, F.J. Longstaffe, and B.D. Neff as co-authors and is currently under review at the journal Evolution. Funding for this project was received through grants to B.D. Neff, F.J. Longstaffe, and S.F. Colborne (see chapter for details). S.R. Garner contributed to the laboratory work and genetic analysis components of this manuscript, as well as providing editorial comments to the chapter. F.J. Longstaffe contributed to the data analysis and provided editorial comments on the chapter. B.D. Neff contributed to the experimental design, statistical analysis, and provided editorial comments on the chapter. A version of Chapter 6 has been submitted to the journal Freshwater Biology for publication and was co-authored with A.M. Clapp, F.J. Longstaffe, and B.D. Neff. Funding for this research was provided to B.D. Neff, F.J. Longstaffe, and S.F. Colborne (see chapter for funding source details). A.M. Clapp completed an undergraduate thesis research project (The University of Western Ontario) which contributed to the data included in this chapter and initial analyses of stomach contents and fish isotopic composition. F.J. Longstaffe contributed to the data analysis and provided editorial comments on this chapter. B.D. Neff contributed to the study design and editorial comments on this chapter. v Acknowledgments First, I would like to thank Bryan Neff, who welcomed me into his lab in May 2009 and has taught me about the scientific process and who I would like to become as a researcher. I have also received guidance from many other faculty members at Western. Fred Longstaffe started as a member of my advisory committee and then welcomed me as a member of the interdisciplinary Laboratory for Stable Isotope Science (LSIS) research group. Chris Guglielmo has provided valuable feedback about my research since my first committee meeting and frequently since that time. I also thank Pedro Peres-Neto, who made my first inter-institutional collaboration a success and who helped me develop the morphological analysis skills used multiple times in my research. I spent almost six months of my Ph.D. studies at the Queen’s University Biological Station (QUBS), a world-class facility for ecology research. Many people contributed to my field work, including Chandra Rodgers, Marie-Christine Bellemare, Tim Hain, Michael Roubakha, Ainsley Furlonger, Adrianna Clapp, Adrienne Berchtold, Malcolm Lau, Aimee Houde, and many students at QUBS who just wanted to come out and learn more about my research. In the lab, I am especially thankful for the help and guidance of Kim Law who taught me more about the technical aspects of isotope analysis then I ever expected. With Kim’s help I never could have run approximately 2000 isotope samples over three years. The past and present members of the Neff lab – Ross Breckels, Melissa Evans, Shawn Garner, Kayla Gradil, Tim Hain, Adam Henkel, Aimee Houde, Malcolm Lau, John Loggie, Nico Muñoz, Charlyn Partridge, Chandra Rodgers, and Jessica Van Zwol – are a special group of people that have made me proud to be a “Neff-ster”. A special thanks to Shawn vi Garner and Charlyn Partridge who provided thorough feedback