The Genetic Basis of Colour Polymorphisms in the South American Poison Frog Dendrobates tinctorius

Abstract

Colour and its evolution have been of great interest to biologists for centuries. In particular, aposematic colouration, whereby animals stand out from their background to warn predators of a harmful defence strategy, deterring attack, has been the subject of much research. Based on principles of natural selection, we would expect to observe convergence of aposematic phenotypes, which would enhance the aposematic signal’s effect, similar to Müllerian mimicry; however, in reality, aposematic species often display a striking diversity of aposematic colour morphs. One of the most famous examples of this can be found in the neotropical poison frogs of the family Dendrobatidae. The aposematic colouration of these frogs has been studied for decades, but until recent years, genetic technologies had not advanced far enough for the molecular basis of colour to be studied in this group. Over the past few years, several studies have begun to investigate this, finding evidence for a key role of differential gene expression in generating these colour polymorphisms. Here, I investigate the genetic basis of colour polymorphisms in Dendrobates tinctorius and compare this to the findings of previous studies into poison frog colour genetics. In my first chapter, I review the existing literature surrounding genetics of colour in animals, with a particular focus on amphibians. As part of this review I produced a list of genes which have been highlighted in other studies of vertebrates as potentially having an impact on colouration. My second chapter focuses on the transcriptome of Dendorbates tinctorius. As this species has not had its genome or transcriptome annotated previously, I compare multiple different annotation methods for this transcriptome, finding that DIAMOND in combination with a Xenopus laevis reference genome produced the most complete annotation. In my third chapter, I compared gene expression levels between the “Azureus” and “Powder Blue” morphs of this species, as well as between “Azureus” adults and tadpoles, finding significant levels of differential gene expression in both comparisons. Combining this analysis with the annotated transcriptome and list of potential colour genes produced in the previous chapters, I was able to identify specific differentially expressed colour genes, many of which had been found in previous studies of poison frog colour genetics in other species. This provides a useful foundation for further research into the evolution of aposematic colour polymorphisms, but highlights the lack of genomic resources for amphibians, and the need for more work in this area.

Date of Award	24 Jun 2026
Original language	English
Awarding Institution	Bangor University
Supervisor	Aaron Comeault (Supervisor) & Alexander Papadopulos (Supervisor)