Systematics of the Great Spangled Fritillary butterfly (Speyeria cybele)

• Author / Creator

  Jackson, Leah G

• The taxonomic rank of species remains a fundamental unit in the study of biodiversity. However, speciation processes are diverse, making it challenging to delimit species. This difficulty is conflated by methodological issues including the use of too few characters, low sample sizes, and prior name changes unsupported by empirical data. To operationalize species taxonomy, numerous species concepts have been proposed to communicate morphological and evolutionary uniqueness, with some also considering biological processes.
  The Great Spangled Fritillary butterfly, Speyeria cybele, provides a challenging case study in species delimitation as its species identity has remained uncertain since its original description. This North American butterfly is well known for its large size, swift flight, and sexually dimorphic wing size and colour pattern. The uncertainty about S. cybele’s species status is largely based on differences between populations east of the Rocky Mountains and those to the west of the Rocky Mountains. Some authors have treated S. cybele as a single variable species with transitions in colour pattern where populations contact. Others recognize western and eastern populations as two distinct species, with western populations being split off as Speyeria leto, which may be sympatric with S. cybele in some regions. However, prior taxonomic and phylogenetic studies of this butterfly have used too few characters or limited sampling of populations, and have not sufficiently quantified morphological differences.
  My study used whole-genome single nucleotide polymorphisms (SNPs), mitochondrial DNA sequences, and wing colour-pattern and size data to assess the population structure of S. cybele. SNPs revealed four major genetic groups that admix to varying extents when populations are in contact. Mitochondrial DNA showed two major haplogroups. The first was restricted to western North America and the second haplotype was geographically unconstrained. Wing morphometrics showed clear sexual dimorphism across North America, and other characters were usually clinal with no sharp boundaries between genetic groupings. By applying the genomic integrity species concept, which distills several other concepts in an effort to provide an objective calibration for species delimitation, I recommend recognition of S. cybele as a single species across North America.

• Subjects / Keywords

  • systematics
  • bioinformatics
  • entomology
  • evolution
  • taxonomy
  • next generation sequencing
  • species delimitation
  • Speyeria
  • ddRAD
  • mtDNA

• Graduation date

  Fall 2024

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-p609-9t50

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.