Selection on Visual Opsin Genes in Diurnal Neotropical Frogs and Loss of the SWS2 Opsin in Poison Frogs

Yin Chen Wan, María José Navarrete Méndez, Lauren A. O’Connell, Lawrence H. Uricchio, Alexandre Benoit Roland, Martine E. Maan, Santiago R. Ron, Mileidy Betancourth-Cundar, Marcio R. Pie, Kimberly A. Howell, Corinne L. Richards-Zawacki, Molly E. Cummings, David C. Cannatella, Juan C. Santos, Rebecca D. Tarvin

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Amphibians are ideal for studying visual system evolution because their biphasic (aquatic and terrestrial) life history and ecological diversity expose them to a broad range of visual conditions. Here, we evaluate signatures of selection on visual opsin genes across Neotropical anurans and focus on three diurnal clades that are well-known for the concurrence of conspicuous colors and chemical defense (i.e., aposematism): poison frogs (Dendrobatidae), Harlequin toads (Bufonidae: Atelopus), and pumpkin toadlets (Brachycephalidae: Brachycephalus). We found evidence of positive selection on 44 amino acid sites in LWS, SWS1, SWS2, and RH1 opsin genes, of which one in LWS and two in RH1 have been previously identified as spectral tuning sites in other vertebrates. Given that anurans have mostly nocturnal habits, the patterns of selection revealed new sites that might be important in spectral tuning for frogs, potentially for adaptation to diurnal habits and for color-based intraspecific communication. Furthermore, we provide evidence that SWS2, normally expressed in rod cells in frogs and some salamanders, has likely been lost in the ancestor of Dendrobatidae, suggesting that under low-light levels, dendrobatids have inferior wavelength discrimination compared to other frogs. This loss might follow the origin of diurnal activity in dendrobatids and could have implications for their behavior. Our analyses show that assessments of opsin diversification in across taxa could expand our understanding of the role of sensory system evolution in ecological adaptation.

Original languageEnglish
Article numbermsad206
JournalMolecular Biology and Evolution
Issue number10
StatePublished - 1 Oct 2023

Bibliographical note

Publisher Copyright:
© The Author(s) 2023. Published by Oxford University Press on behalf of Society for Molecular Biology and Evolution.


  • Atelopus
  • Brachycephalus
  • Dendrobatidae
  • blue-sensitive opsin
  • gene loss
  • spectral tuning


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