Victor Aaron Shegelski
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Mountain pine beetle dispersal: morphology, genetics, and range expansion by Victor Aaron Shegelski A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Systematics and Evolution Department of Biological Sciences University of Alberta © Victor Aaron Shegelski, 2020 Abstract Dispersal by flight is a complex life history phase in many insects that is essential to gene flow and range expansion. Many elements contribute to realized dispersal, including biotic and abiotic environmental conditions, as well as intrinsic factors such as morphology, physiology and behavior. Dispersal is often associated with economic consequences in pest species, and understanding its correlates can inform control efforts. In this thesis I investigate dispersal from a micro to macro scale using the mountain pine beetle (Dendroctonus ponderosae) as a study system. I begin by testing relationships between empirically observable flight morphology and dispersal capacity, as measured using computer-linked flight mills. I also relate dispersal capacity to genetic variation using RNA-seq and a targeted association study to identify genes and genetic markers associated with a dispersal phenotype. I then shift focus to identify large scale patterns of dispersal across the landscape, using genomic single nucleotide polymorphisms (SNPs). In this research I found several flight-related traits and genes. Morphologically, variation in dispersal capacity is related to wing size and body weight. These traits, however, only explained approximately 20% of the variation, indicating that other factors, such as genetic variation, also contribute to a “dispersal phenotype”. Analysis of gene expression by comparing beetles with strong and weak dispersal capacity revealed over 2,700 differentially expressed genes and 4 genetic markers associated with flight performance. Many of these genes related to physiology, hormonal control, behavior, and detoxification, which may have implications for landscape-scale dispersal success. By investigating dispersal dynamics of mountain pine beetle across central Alberta, I identified the sources of current outbreaks at leading-edge populations and found evidence for long-range dispersal and high rates of gene flow between populations. ii This work represents a synthesis of different approaches to dispersal-related research in which I investigated morphological, physiological and behavioral traits, as well as landscape-scale patterns of dispersal, using empirical measurements, genetics, and flight mill-measured dispersal capacity. I present a methodological approach to studying dispersal on several scales and contribute to our understanding of the many factors associated with insect dispersal by flight. iii Preface A version of Chapter 2 has been published as Shegelski VA, Evenden ML, Sperling FAH (2019) “Morphological variation associated with dispersal capacity in a tree-killing bark beetle Dendroctonus ponderosae Hopkins”, Agriculture and Forest Entomology volume 21, pages 79- 97. VAS performed the analysis and drafted the manuscript. Flight mills in the lab of MLE were used to acquire flight data. All authors contributed to the study design and manuscript revisions. A version of Chapter 4 has been submitted for publication, authored by Shegelski VA, Campbell EO, Thompson KM, Whitehouse CM, and Sperling FAH. Structure analysis was performed by EOC, and all other aspects of the analysis, as well as drafting of the manuscript, were performed by VAS. Many samples were supplied by CMW or KMT. All authors contributed to study design and manuscript revisions. iv Acknowledgements To get to this point, I have been supported by a veritable army, but I would like to start by thanking my supervisor, who took a chance on an ex-military wildcard. Thank you, Felix. You have been the ideal supervisor. You provided a perfect blend of direction and creative freedom. I can understand that a student like me could not always have been easy; we have butted heads on several occasions, but, like a true “Bayesian” intellectual, you were flexible in your thinking, and you certainly taught me to do the same. Thank you, Maya and Dezene, for being on my committee and supporting me through these trials. Maya, you gave me the chance to be a part of your field research (chainsaw and shotgun training was a blast… no pun intended), and you had some serious patience in helping me get my first paper published. Dezene, you have provided some great theoretical insight, and your encouragement has been invaluable. I would also like to thank the “army” that helped with this research through sample collection, advice and great discussion: Stephane Bordeleau, Jackson Lai, Dylan Sjolie, Caroline Whitehouse, Bryan Brunet, Phil Batista, Sebastian Lackey, Corey Davis, Devin Letourneau, Melodie Kunegel-Lion, Stephen Trevoy, Nils Koch, Nathan Marculis, John Haley, Tiago Simões, Oksana Vernygora, Andrew Sperling, William Sperling, Janet Sperling, Neil Thompson, Jennifer McCormmack, Fraser McKee, Asha Wijerathna, and the crew down at the MBSU (Troy and Sophie). Also, Julian Dupuis, Ronald Batallas, members of the Sperling Lab, and, of course, the wonderous “Core Four”, Tyler, Brittany, and Erin. We had some doggone good times. Thank you, Mom, Dad, Adam, Mandy, Trevor and Lianne, for your support, and for forging who I am today. Thank you, Kyla, my wife, for you unwavering support through the last v few years. It has been an adventure having children as we simultaneously faced the constant challenge of clawing out our respective professional niches. Regardless, with your support I have overcome insurmountable difficulties. I love you, and I am capable of anything when I have you by my side. Isaac, you have been amazingly patient with ‘Dah-dee’ and have made life infinitely richer. And Hazel, welcome to the world! Thank you for being patient enough to wait until after I wrote this thesis. Thank you to all my in-laws. Many cringe at the thought of having one set of in-laws, but I have two, and I love you all. In this, I know I have won the lottery. Shannon, Thank you for your weekly help with caring for Isaac. I would not have been able to complete my work in time if not for you. I also thank my late wife, Michelle Shegelski (née Ernst) for setting me on this path. Without your guidance, I never would have discovered my love of teaching and the academic world. This research was supported by: (1) a grant to Dr. Maya Evenden and Dr. Felix Sperling from the Natural Science and Engineering Research Council of Canada to the TRIA Network, with contributions from Alberta Agriculture and Forestry, fRI Research, Manitoba Conservation and Water Stewardship, Natural Resources Canada - Canadian Forest Service, Northwest Territories Environment and Natural Resources, Ontario Ministry of Natural Resources and Forestry, Saskatchewan Ministry of Environment, West Fraser and Weyerhaeuser; (2) an NSERC Discovery Grant to F. Sperling; and (3) the Government of Alberta. vi Table of Contents Abstract ..................................................................................................................................... ii Preface ....................................................................................................................................... iv Acknowledgements ................................................................................................................... v List of Figures ............................................................................................................................ x List of Tables ............................................................................................................................ xi List of Abbreviations ............................................................................................................. xii List of Appendices ................................................................................................................. xiii Introduction ............................................................................................................................... 1 1.1 Insect dispersal .................................................................................................................. 1 1.2 Investigating the correlates of dispersal ............................................................................ 2 1.3 Systematics, life history and impact of the mountain pine beetle ..................................... 4 1.4 Morphological and genetic correlates of flight in mountain pine beetle ........................... 8 1.5 Population dynamics of mountain pine beetle ................................................................ 10 1.6 Thesis Objectives ............................................................................................................ 11 Morphological variation associated with dispersal capacity in a tree-killing bark beetle Dendroctonus ponderosae Hopkins ........................................................................................ 13 2.1 Summary ......................................................................................................................... 13 2.2 Introduction ..................................................................................................................... 14 2.3 Methods ........................................................................................................................... 17 2.3.1 Beetle data collection