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Fig. 1 | BMC Evolutionary Biology

Fig. 1

From: A pleiotropic interaction between vision loss and hypermelanism in Astyanax mexicanus cave x surface hybrids

Fig. 1

Hypermelanic cave x surface hybrid fish are significantly darker than wild type surface-dwelling fish. A representative hypermelanic individual from a cave x surface F2 pedigree (a), a DD surface fish maintained under a 24 h dark cycle (b) and a LD surface fish reared under a normal 12 h light: 12 h dark photic cycle (c) were imaged to illustrate differences in melanophore numbers and morphology (7.8× magnification). Mean pigmentation darkness (d) was measured from extracted melanin isolated from fin tissue via a greyscale analysis in ImageJ (0 = White, 255 = Black). Hypermelanic fish were significantly darker than DD and LD surface fish, as well as albino Pachón cavefish (**p = 0.0022; ***p < 0.0001; Bonferroni corrected p-value for significance = 0.0083). A mean coloration analysis (e) of the extracted fin tissue in Adobe Photoshop revealed no significant differences between hypermelanic individuals and DD reared surface fish across cyan, magenta, yellow and keyed (black) color channels, however, there were significant differences noted across color channels when comparing hypermelanic and surface DD fish to both surface LD and Pachón cavefish (**p = 0.006; ***p < 0.0001; Bonferroni corrected p-value for significance = 0.0083). Comparing hypermelanic fish (HM), Surface DD and Surface LD, significant differences in greyscale were noted for the following: HM ≠ DD, LD, and Pachón; DD and LD ≠ Pachón (d). Comparing all groups, significant differences in coloration were noted for the following color channels: Magenta: DD ≠ LD; Keyed: DD ≠ LD. Note that Pachón cavefish differed from all groups in all four coloration channels (e)

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