Functional colour genes and signals of selection in colour polymorphic salamanders

James D. Burgon, David R. Vieites, Arne Jacobs, Stefan K. Weidt, Helen M. Gunter, Sebastian Steinfartz, Karl Burgess, Barbara K. Mable, Kathryn R. Elmer

Research output: Contribution to journalArticlepeer-review

Abstract

Colouration has been associated with multiple biologically relevant traits that drive adaptation and diversification in many taxa. However, despite the great diversity of colour patterns present in amphibians the underlying molecular basis is largely unknown. Here, we leverage insight from a highly colour‐variable lineage of the European fire salamander (Salamandra salamandra bernardezi) to identify functional associations with striking variation in colour morph and pattern. The three focal colour morphs—ancestral black‐yellow striped, fully yellow, and fully brown—differed in pattern, visible colouration, and cellular composition. From population genomic analyses of up to 4,702 loci, we found no correlations of neutral population genetic structure with colour morph. However we identified 21 loci with genotype‐phenotype associations, several of which relate to known colour genes. Further, we inferred response to selection at up to 142 loci between the colour morphs, again including several that relate to colouration genes. By transcriptomic analysis across all different combinations, we found 196 differentially expressed genes between yellow, brown, and black skin, 63 of which are candidate genes involved in animal colouration. The concordance across different statistical approaches and ‘omic datasets provide several lines of evidence for loci linked to functional differences between colour morphs, including TYR, CAMK1, and PMEL. We found little association between colour morph and the metabolomic profile of its toxic compounds from the skin secretions. Our research suggests that current ecological and evolutionary hypotheses for the origins and maintenance of these striking colour morphs may need to be revisited.
Original languageEnglish
Pages (from-to)1284-1299
JournalMolecular Ecology
DOIs
Publication statusPublished - 11 Mar 2020

Keywords

  • amphibian
  • colouration
  • genetic architecture
  • gene expression
  • genomic association
  • response to selection
  • population genomics
  • toxicity
  • colour candidate genes

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