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Mechanisms for color convergence in a mimetic radiation of poison frogs

Citation

Twomey, Evan et al. (2019), Mechanisms for color convergence in a mimetic radiation of poison frogs, Dryad, Dataset, https://doi.org/10.5061/dryad.z34tmpg8f

Abstract

In animals, bright colors often evolve to mimic other species when a resemblance is selectively favored. Understanding the proximate mechanisms underlying such color mimicry can give insights into how mimicry evolves, for example, whether color convergence evolves from a shared set of mechanisms or through the evolution of novel color production mechanisms. We studied color production mechanisms in poison frogs (Dendrobatidae), focusing on the mimicry complex of Ranitomeya imitator. Using reflectance spectrometry, skin pigment analysis, electron microscopy, and color modeling, we found that the bright colors of these frogs, both within and outside the mimicry complex, are largely structural and produced by iridophores, but that color production depends crucially on interactions with pigments. Color variation and mimicry is regulated predominantly by iridophore platelet thickness and, to a lesser extent, concentration of the red pteridine pigment drosopterin. Compared to each of the four morphs of model species which it resembles, R. imitator displays greater variation in both structural and pigmentary mechanisms, which may have facilitated phenotypic divergence in this species. Analyses of non-mimetic dendrobatids in other genera demonstrate that these mechanisms are widespread within the family, and that poison frogs share a complex physiological “color palette” that can produce diverse and highly reflective colors.

Methods

see manuscript

Usage Notes

see README document

A description of how to use these scripts is available in "top_level_text.R"

In order to properly use these scripts, read all of the documentation until the heading "code"

Note: The structural color production model presented here relies on methods (matrix transfer function "multilayer_adj" in "functions.R") previously developed by: Maia, R., Caetano, J. V. O., Bao, S. N., & Macedo, R. H. (2009). Iridescent structural colour production in male blue-black grassquit feather barbules: the role of keratin and melanin. Journal of the Royal Society Interface, 6(suppl_2), S203-S211.

See link to projects github repository below

https://github.com/morgankain/Twomey_et_al_color_mimicry