Phenotypic and genetic variation in Rocky Mountain bighorn sheep (Ovis canadensis canadensis)

• Author / Creator

  Deakin, Samuel

• Genetic variation is a ubiquitous feature of natural populations and underpins much phenotypic variation. Genetic variance can be partitioned and examined at various hierarchical levels of organization to address fundamental questions in ecology and evolution. Patterns of genetic variance among populations reveals population structure or potential local adaptation, whereas we need to examine genetic variation among individuals within populations to study the genetic architecture underlying phenotypic variation. My thesis examined genetic and phenotypic variance in Rocky Mountain bighorn sheep (Ovis canadensis canadensis) across these scales of organization. I examined population level variation in bighorn sheep across the northern portion of their range in Alberta using microsatellite genetic markers and found that their spatial genetic structure was delineated by inter-river valley regions and showed a strong pattern of isolation-by-distance. Additionally, I identified patterns of spatial genetic structure which indicated gene flow occurred equally between the sexes up to 100km. I also identified declines in genetic diversity moving northwards, which suggests the post-glacial recolonization of the northern Rocky Mountains by bighorn sheep was sourced from the Southern refugium. Within the Ram Mountain population, I then examined the fitness consequences of phenotypic variation at the individual level. I found that longer horned females reproduced and successfully raised offspring earlier in life, and therefore produced more lambs over their lifetime. This highlighted how presumed vestiges of strong sexual selection on males can indicate individual fitness in females, similar to their male counterparts. To investigate the genetic basis of phenotypic variance, I developed a high-density species-specific SNP assay to genotype Rocky Mountain bighorn sheep at 50,000 loci. Using genotypes from this assay and phenotypic data from 305 individuals at the Ram Mountain population, I investigated the genetic basis of eight traits: male and female body mass, male and female horn length, female age at primiparity, female age at first weaning success, female lifetime reproductive success, and female longevity. I identified 278 loci associated with these traits and further characterised eight focal loci. Of these eight loci, I identified one associated with male horn length that showed temporal patterns consistent with an evolutionary response to selection by trophy hunting in the Ram Mountain population.

• Subjects / Keywords

  • population genetics
  • population genomics
  • bighorn sheep
  • genomics
  • selective harvest
  • genetics
  • ungulate
  • ecology

• Graduation date

  Fall 2023

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-k7zd-x653

• License

  This thesis is made available by the University of Alberta Libraries 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.