Genetics of adaptation in colourful poison frogs
General Genetics and Functional Genome Biology
Final Report Abstract
Animal coloration is an adaptive attribute, subject to strong local selection pressures and therefore often diversified among species or populations. The visually conspicuous strawberry poison frog Oophaga pumilio shows broad array of color morphs across its distribution in the rain forests in Central America. While the ecological factors contributing to this impressive phenotypic color divergence have been extensively investigated, the contribution of molecular processes has been neglected so far. We collected skin samples from on the mainland and the islands of the Bocas del Toro archipelago differing in coloration. RNA was extracted from 15 samples and subsequently sequenced (RNA-Seq). Based on sequence information we applied biostatistical analyses (RNA-Seq gene expression analysis) in order to identify candidate genes involved in coloration divergences among red, blue and green colored frogs. First we assembled de novo a reference transcriptome containing 20494 coding transcripts and used it to estimate the differences in gene expression between color morphs. Differential expression (DE) was quantified and statistically tested using three methods (limma, edgeR, and DESeq2). A set 735 coding transcripts were identified as DE by the three detection methods applied. Approximately 8% of these transcripts represented genes previously linked to pigment production pathways, including carotenoid A metabolism, pteridine production, melanin synthesis, purine metabolism and genes in the Cytochrome P450 family. Further analyses (gene set enrichment) indicated that genes in the pteridine pathway were upregulated in red relative to blue color frogs. This result fits our expectation since pteridines are red pigments. Genes in the melanin synthesis pathway were upregulated in green relative to blue frogs. Melanin is a pigment that contributes to dark coloration. Expression patterns of several of these genes are analyzed and their potential role in color variation inferred based on published studies on model organisms. Overall our results identify multiple candidate genes associated to color phenotypes which will open new avenues for future studies of color variation in frogs and other organisms.
Publications
- Red versus blue versus green: Molecular aspects of color polytypy in a poison frog. GTÖ meeting, Paris 2018
Pröhl H, Rodriguez A, Mundy N
