Variation in pigmentation gene expression is associated with distinct aposematic color morphs in the poison frog, Dendrobates auratus

Abstract

13Color and pattern phenotypes have clear implications for survival and reproduction in many species. 14 However, the mechanisms that produce this coloration are still poorly characterized, especially at the genomic level. 15Here we have taken a transcriptomics-based approach to elucidate the underlying genetic mechanisms affecting 16 color and pattern in a highly polytypic poison frog. We sequenced RNA from the skin from four different color 17 morphs during the final stage of metamorphosis and assembled a de novo transcriptome. We then investigated 18 differential gene expression, with an emphasis on examining candidate color genes from other taxa. Overall, we 19 found differential expression of a suite of genes that control melanogenesis, melanocyte differentiation, and 20 melanocyte proliferation (e. g., tyrp1, lef1, leo1, and mitf) as well as several differentially expressed genes involved in 21 purine synthesis and iridophore development (e.g., arfgap1, arfgap2, airc, and gairt). Our results provide evidence 22 that several gene networks known to affect color and pattern in vertebrates play a role in color and pattern variation 23 in this species of poison frog. 24 25 Introduction: 26

RETRACTED: The genomics of mimicry: Gene expression throughout development provides insights into convergent and divergent phenotypes in a Müllerian mimicry system

“…Black and brown coloration is produced by melanophores and the melanin pigments found within the chromatophores (Bagnara et al, 1968; Duellman & Trueb, 1986. These data are corroborated by new genomic data that seem to highlight the importance of pigment production and modification genes such as those in the melanin synthesis pathway (Stuckert et al, 2019; Posso‐Terranova & Andrés, 2017), pteridine synthesis pathway (Rodríguez et al, 2020; Stuckert et al, 2019) and carotenoid processing pathways (Twomey, Johnson, et al, 2020) for their roles in producing different colour morphs in poison frogs.…”

“…We also found differential expression of a number of genes that are known to impact guanine or purine synthesis throughout development ( adsl , gart , gas1 , fh , qdpr ) and between colour morphs ( atic , psat1 , qdpr ). A number of these genes ( adsl , dct , dock7 , gart , fh , qdpr , psat1 , rabggta ) have been implicated in previous work in dendrobatids (Rodríguez et al, 2020; Stuckert et al, 2019) and in other taxa. The genes that have been implicated in previous studies are clearly good candidates for future study.…”

“…auratus and O . pumilio (Rodríguez et al, 2020; Stuckert et al, 2019). Experimental inhibition of xdh causes a reduction in the quantity of pterins, resulting in an atypical black appearance in axolotls (Frost, 1978; Frost & Bagnara, 1979; Thorsteinsdottir & Frost, 1986).…”

“…Unfortunately, our understanding of how these genes affect the development of iridophores is limited, and thus more targeted examinations of iridophore production and pigment production are needed. Notably, a number of epidermis‐structuring genes (such as those in the krt family) have been implicated in the production of structural colours (e.g., krt1 , krt2 ), although more evidence is needed to verify their role in coloration (Burgon et al, 2020; Cui et al, 2016; McGowan et al, 2006; Stuckert et al, 2019). We identified a number of these that are differentially expressed between colour morphs (e.g., krt1 , krt2 , krt10 , krt14 , krt5 ).…”

“…Furthermore, despite the arrival of new genomic data that provide critical insights into the mechanisms of colour production in amphibians in general (Burgon et al, 2020), and poison frogs in particular (Rodríguez et al, 2020; Stuckert et al, 2019; Twomey et al, 2020), our knowledge of amphibian genomics is critically behind that of other tetrapods, both in terms of genomic resources as well as in our ability to make inferences from these resources. This is largely due to the challenging nature of these genomes, most of which are extremely large (frog genomes range from 1 to 11 Gbp, with an interquartile range of 3–5 Gbp; Funk et al, 2018) and rich with repeat elements that have proliferated throughout the genome (Rogers et al, 2018).…”