Coloration is perhaps one of the most prominent adaptations for survival and reproduction of many taxa. Coloration is of particular importance for aposematic species, which rely on their coloring and patterning acting as a warning signal to deter predators. Most research has focused on the evolution of warning coloration by natural selection. However, little information is available for color mutants of aposematic species, particularly at the genomic level. Here, I compare the transcriptomes of albino mutant caterpillars of the aposematic wood tiger moth (Arctia plantaginis) to those of their full sibs having their distinctive orange-black warning coloration. The results showed >290 differentially expressed genes genome-wide. Genes involved in the immune system, structural constituents of cuticular, and immunity were mostly downregulated in the albino caterpillars. Surprisingly, higher expression was observed in core melanin genes from albino caterpillars, suggesting that melanin synthesis may be disrupted in terminal ends of the pathway during its final conversion. Taken together, these results suggest that caterpillar albinism may not be due to a depletion of melanin precursor genes. In contrast, the albino condition may result from the combination of faulty melanin conversion late in its synthesis and structural deficiencies in the cuticular preventing its deposition. The results are discussed in the context of how albinism may impact individuals of aposematic species in the wild.

中文翻译：

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白化病和警告色毛虫的比较转录组学

着色可能是许多分类群生存和繁殖的最突出的适应之一。着色对于隐性物种尤其重要，它们依赖于它们的着色和图案作为威慑掠食者的警告信号。大多数研究都集中在自然选择对警告颜色的演变上。然而，关于隐性物种的颜色突变体的信息很少，特别是在基因组水平上。在这里，我比较了 aposematic 木虎蛾 ( Arctia plantaginis )的白化突变毛虫的转录组) 到那些具有独特的橙黑色警告色的完整同胞。结果显示 > 290 个差异表达的基因全基因组。参与免疫系统、表皮结构成分和免疫的基因在白化毛虫中大多被下调。令人惊讶的是，在来自白化病毛虫的核心黑色素基因中观察到更高的表达，这表明黑色素合成在其最终转化过程中可能在该途径的末端被破坏。总之，这些结果表明毛毛虫白化病可能不是由于黑色素前体基因的消耗。相比之下，白化病可能是由于黑色素合成后期的错误转化和角质层中阻止其沉积的结构缺陷的组合造成的。