References for Table 2 1. Martin, M. D., & Mendelson, T. C. (2012). Signal divergence is correlated with genetic distance and not environmental differences in darters (Percidae: Etheostoma). Evol. Biol., 39(2), 231-241. 2. Gumm, J. M., & Mendelson, T. C. (2011). The evolution of multi-component visual signals in darters (genus Etheostoma). Curr. Zool., 57(2), 125-139. 3. Williams, T. H., & Mendelson, T. C. (2011). Female preference for male coloration may explain behavioural isolation in sympatric darters. Anim. Behav., 82(4), 683-689. 4. Mendelson, T. C. (2003). Sexual isolation evolves faster than hybrid inviability in a diverse and sexually dimorphic genus of fish (Percidae: Etheostoma). Evolution, 57(2), 317-327. 5. Claridge, M. F., & Morgan, J. C. (1993). Geographical variation in acoustic signals of the planthopper, Nilaparvata bakeri (Muir), in Asia: species recognition and sexual selection. Biol. J. Linn. Soc., 48(3), 267-281. 6. Amézquita, A., Lima, A. P., Jehle, R., Castellanos, L., Ramos, O., Crawford, A. J., & Hoedl, W. (2009). Calls, colours, shape, and genes: a multi‐trait approach to the study of geographic variation in the Amazonian frog Allobates femoralis. Biol. J. Linn. Soc., 98(4), 826-838. 7. Amézquita, A., Hödl, W., Lima, A. P., Castellanos, L., Erdtmann, L., & Araújo, M. C. (2006). Masking interference and the evolution of the acoustic communication system in the Amazonian dendrobatid frog Allobates femoralis. Evolution, 60(9), 1874-1887. 8. Campbell, P., Pasch, B., Pino, J. L., Crino, O. L., Phillips, M., & Phelps, S. M. (2010). Geographic variation in the songs of neotropical singing mice: testing the relative importance of drift and local adaptation. Evolution, 64(7), 1955-1972. 9. Rudh, A., Rogell, B., & Höglund, J. (2007). Non‐gradual variation in colour morphs of the strawberry poison frog Dendrobates pumilio: genetic and geographical isolation suggest a role for selection in maintaining polymorphism. Mol. Ecol., 16(20), 42844294. 10. Summers, K., Cronin, T. W., & Kennedy, T. (2003). Variation in spectral reflectance among populations of Dendrobates pumilio, the strawberry poison frog, in the Bocas del Toro Archipelago, Panama. J. Biogeog., 30(1), 35-53. 11. Summers, K., Symula, R., Clough, M., & Cronin, T. (1999). Visual mate choice in poison frogs. Proc. Roy. Soc. B, 266(1434), 2141-2145. 12. Reynolds, R. G., & Fitzpatrick, B. M. (2007). Assortative mating in poison-dart frogs based on an ecologically important trait. Evolution, 61(9), 2253-2259. 13. Crothers, L., Gering, E., & Cummings, M. (2011). Aposematic signal variation predicts male–male interactions in a polymorphic poison frog. Evolution, 65(2), 599605. 14. Summers, K., Cronin, T. W., & Kennedy, T. (2004). Cross-breeding of distinct color morphs of the strawberry poison frog (Dendrobates pumilio) from the Bocas del Toro Archipelago, Panama. J. Herpetol., 38(1), 1-8. 15. Richards-Zawacki, C. L., Yeager, J., & Bart, H. P. (2013). No evidence for differential survival or predation between sympatric color morphs of an aposematic poison frog. Evol. Ecol., 27(4), 783-795. 16. Hegna, R. H., Saporito, R. A., & Donnelly, M. A. (2012). Not all colors are equal: predation and color polytypism in the aposematic poison frog Oophaga pumilio. Evol.Ecol., 1-15. 17. Jouventin, P., Cuthbert, R. J., & Ottvall, R. (2006). Genetic isolation and divergence in sexual traits: evidence for the northern rockhopper penguin Eudyptes moseleyi being a sibling species. Mol. Ecol., 15(11), 3413-3423. 18. Ritchie, M. G., & Gleason, J. M. (1995). Rapid evolution of courtship song pattern in Drosophila willistoni sibling species. J. Evolution. Biol., 8(4), 463-479. 19. Gleason, J. M., & Ritchie, M. G. (1998). Evolution of courtship song and reproductive isolation in the Drosophila willistoni species complex: Do sexual signals diverge the most quickly? Evolution, 52(5), 1493-1500. 20. Seddon, N., & Tobias, J. A. (2007). Song divergence at the edge of Amazonia: an empirical test of the peripatric speciation model. Biol. J. Linn. Soc., 90(1), 173-188. 21. Elias, D. O., Hebets, E. A., & Hoy, R. R. (2006). Female preference for complex/novel signals in a spider. Behav. Ecol., 17(5), 765-771.