The Genomic Consistency of the Loss of Anadromy in an Arctic Fish (Salvelinus alpinus)

Sarah Salisbury, Gregory R. McCracken, Robert Perry, Donald Keefe, Kara K. S. Layton, Tony Kess, Cameron M. Nugent, Jong S. Leong, Ian R. Bradbury, Ben F. Koop, Moira M. Ferguson, Daniel E. Ruzzante

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Abstract

The potentially significant genetic consequences associated with the loss of migratory capacity of diadromous fishes that have become landlocked in freshwater are poorly understood. Consistent selective pressures associated with freshwater residency may drive repeated differentiation both between allopatric landlocked and anadromous populations and within landlocked populations (resulting in sympatric morphs). Alternatively, the strong genetic drift anticipated in isolated landlocked populations could hinder consistent adaptation, limiting genetic parallelism. Understanding the degree of genetic parallelism underlying differentiation has implications for both the predictability of evolution and management practices. We employed an 87k single-nucleotide polymorphism (SNP) array to examine the genetic characteristics of landlocked and anadromous Arctic char (Salvelinus alpinus) populations from five drain-ages within Labrador, Canada. One gene was detected as an outlier between sympatric, size-differentiated morphs in each of two landlocked lakes. While no single locus differentiated all replicate pairs of landlocked and anadromous populations, several SNPs, genes, and paralogs were consistently detected as outliers in at least 70% of these pairwise comparisons. A significant C-score suggested that the amount of shared outlier SNPs across all paired landlocked and anadromous populations was greater than expected by chance. Our results indicate that despite their isolation, selection due to the loss of diadromy may drive consistent genetic responses in landlocked populations.

Original languageEnglish
Pages (from-to)617-635
Number of pages19
JournalThe American Naturalist
Volume199
Issue number5
Early online date31 Mar 2022
DOIs
Publication statusPublished - 1 May 2022

Keywords

  • SNPs
  • allopatry
  • anadromy
  • incipient speciation
  • landlocked
  • parallelism
  • PARALLEL EVOLUTION
  • GENE DIVERSITY ANALYSIS
  • CHARR
  • POPULATION-STRUCTURE
  • R PACKAGE
  • LABRADOR
  • SELECTION
  • EXPRESSION
  • ECOLOGICAL GENOMICS
  • INSIGHTS

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