Mountain pine beetle dispersal: morphology, genetics, and range expansion

  • Author / Creator
    Shegelski, Victor A
  • 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.
    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.

  • Subjects / Keywords
  • Graduation date
    Fall 2020
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
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