Washington University in St. Louis Washington University Open Scholarship Arts & Sciences Electronic Theses and Dissertations Arts & Sciences Summer 8-15-2016 Population Structure and Mating Dynamics in the Social Amoeba Dictyostelium discoideum Tracy Edwards Douglas Washington University in St. Louis Follow this and additional works at: https://openscholarship.wustl.edu/art_sci_etds Recommended Citation Douglas, Tracy Edwards, "Population Structure and Mating Dynamics in the Social Amoeba Dictyostelium discoideum" (2016). Arts & Sciences Electronic Theses and Dissertations. 843. https://openscholarship.wustl.edu/art_sci_etds/843 This Dissertation is brought to you for free and open access by the Arts & Sciences at Washington University Open Scholarship. It has been accepted for inclusion in Arts & Sciences Electronic Theses and Dissertations by an authorized administrator of Washington University Open Scholarship. For more information, please contact [email protected]. WASHINGTON UNIVERSITY IN ST. LOUIS Division of Biology & Biomedical Sciences Evolution, Ecology & Population Biology Dissertation Examination Committee: Joan Strassmann, Chair David Queller, Chair Scott Mangan Ken Olsen James Umen Population Structure and Mating Dynamics in the Social Amoeba Dictyostelium discoideum by Tracy Edwards Douglas A dissertation presented to the Graduate School of Arts and Sciences of Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy August 2016 St. Louis, Missouri © Copyright 2016 by Tracy Edwards Douglas. TABLE OF CONTENTS List of Figures ............................................................................................................................... iv List of Tables ..................................................................................................................................v Acknowledgments ........................................................................................................................ vi Abstract of the Dissertation ........................................................................................................ ix Chapter 1: Introduction to the Dissertation ................................................................................1 Background ...................................................................................................................................2 Study System ................................................................................................................................4 Dissertation Overview ..................................................................................................................7 Literature Cited .............................................................................................................................9 Chapter 2: Genetic diversity in the social amoeba Dictyostelium discoideum: population differentiation and cryptic species .............................................................................................15 Abstract ......................................................................................................................................16 Introduction ................................................................................................................................17 Materials and Methods ...............................................................................................................20 Results ........................................................................................................................................23 Discussion ..................................................................................................................................27 Literature Cited ..........................................................................................................................32 Chapter 3: Sex ratio and gamete size across eastern North America in Dictyostelium discoideum, a social amoeba with three sexes ...........................................................................42 Abstract ......................................................................................................................................43 Introduction ................................................................................................................................44 Materials and Methods ...............................................................................................................48 Results ........................................................................................................................................52 Discussion ..................................................................................................................................54 Literature Cited ..........................................................................................................................58 Chapter 4: Social amoebae mating types do not invest unequally in sexual offspring..........68 Abstract ......................................................................................................................................69 Introduction ................................................................................................................................70 Materials and Methods ...............................................................................................................73 Results ........................................................................................................................................77 Discussion ..................................................................................................................................80 Literature Cited ..........................................................................................................................86 ii Chapter 5: Conclusion to the Dissertation.................................................................................96 Literature Cited ........................................................................................................................101 Appendix 1: Supplementary Tables for Chapter 2 .................................................................104 Appendix 2: Supplementary Tables for Chapter 3 .................................................................109 Appendix 3: Supplementary Figures and Tables for Chapter 4 ...........................................117 iii List of Figures Figure 1.1: Dictyostelium discoideum sexual life cycle. ..............................................................14 Figure 2.1: Geographic locations of Dictyostelium discoideum clones used in Chapter 1 ...........39 Figure 2.2: Bayesian phylogenetic trees created from (a) mitochondrial and (b) ribosomal DNA sequence data, with Bayesian posterior probablilities and cooresponding neighbor-joining bootstrap values.. ...........................................................................................................................40 Figure 2.3: Bayesian phylogenetic tree created from combined mitochondrial and ribosomal DNA sequence data, with Bayesian posterior probabilities and cooresponding neighbor-joining bootstrap values. ............................................................................................................................41 Figure 3.1: Gametes are larger in Virginia, but are the same across mating types. ......................66 Figure 3.2: Mating type proportions vary by population. .............................................................67 Figure 4.1: Differential macrocyst production in Dictyostelium discoideum. ..............................91 Figure 4.2: An example of a diffusion chamber between NC4 and V12 with the combinations of clones to be tested and the expected outcomes for each combination. ..........................................92 Figure 4.3: Predicted outcomes of different hypotheses...............................................................93 Figure 4.4: Type I WS205 induces macrocyst production in Type II IR1, and Type II V12 induces macrocyst production in Type I NC4. ..............................................................................94 Figure 4.5: Fewer macrocysts are formed when either mating type in a pairing is very rare. ....95 iv List of Tables Table 2.1: Pairwise Fst values between populations of Dictyostelium discoideum with sample sizes greater than 7 individuals ......................................................................................................38 Table 3.1: FST and G’ST values show differentiation in mating type frequencies and microsatellite allele frequencies between populations of Dictyostelium discoideum ....................65 v Acknowledgments First, I thank my advisors Joan Strassmann and Dave Queller. When I started as an undergraduate researcher, I had no idea how long my journey in their lab would be. For the past decade, they have provided me with academic guidance and support. They encouraged me to love what I do, ask bigger questions, defend my research goals, and find a healthy and satisfying work-life balance. I would not be the scientist I am today were it not for them. I am forever grateful. I thank the rest of my dissertation committee members, Ken Olsen, Jim Umen, and Scott Mangan, for helpful comments, encouragement, and thought-provoking discussions of my dissertation research. I also thank original members of my dissertation committee