The adaptive diversity of Arctic charr (Salvelinus alpinus) in Scotland

Fenton, Sam (2024) The adaptive diversity of Arctic charr (Salvelinus alpinus) in Scotland. PhD thesis, University of Glasgow.

Abstract

Intraspecific, within-species, diversity is critical to the continued existence of populations, species, and entire ecosystems and so the conservation of intraspecific diversity is increasingly valued in conservation policy. The Arctic charr (Salvelinus alpinus) represents one of the most highly diverse species in the world with high levels of phenotypic and genetic variation seen across its Holarctic range including the appearance of distinct trophic specialist populations. The emergence of such a vast range of phenotypes and genotypes makes the Arctic charr a key study system for exploring the process behind the emergence of biodiversity. The high diversity seen gives the species high conservation and scientific value but also makes defining important units of conservation to protect that diversity challenging, with questions about whether Arctic charr should even be considered a single species. Defining these units of conservation and understanding the factors underlying patterns of genetic diversity and differentiation requires large-scale genetic studies, currently lacking in the British Isles.

In this thesis, I investigated patterns of genetic differentiation and structuring across Scotland and the rest of the British Isles to define important units of conservation in Arctic charr. I highlighted instances of trophic specialist populations, known as ecotypes, as high priority for conservation action while questioning an existing taxonomy of endemic species which were delineated based on phenotypic characteristics. I investigated the factors the underlie the emergence of diversity highlighting ecosystem size as important in the extent of phenotypic and genetic diversity seen but also for underlying instances of trophic specialisation. Analysis of the colonisation history of Arctic charr revealed that the British Isles were colonised by multiple distinct ancestral sub-lineages and that glacial history had a major role in shaping patterns of genetic differentiation and diversity with regions still covered by ice during the colonisation period of the species. Finally, I investigated the genomics of key phenotypes that underlie repeated instances of trophic specialisation finding that only small numbers of SNPs were shared across replicates indicating the use of different genomic pathways to achieve similar phenotypes. This thesis represents an important body of work both for the conservation of Arctic char but more broadly our understanding of the emergence of diversity and the repeatability of evolution.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QH Natural history > QH426 Genetics
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Supervisor's Name: Adams, Professor Colin, Bean, Professor Colin and Elmer, Professor Kathryn
• Date of Award: 2024
• Depositing User: Theses Team
• Unique ID: glathesis:2024-84449
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 05 Jul 2024 15:22
• Last Modified: 01 Sep 2026 14:59
• Thesis DOI: 10.5525/gla.thesis.84449
• URI: https://theses.gla.ac.uk/id/eprint/84449

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