The Mesoamerican cichlids display a spectacular diversity of pigment patterns, which serve a variety of functions and serve as a strong selective trait for this lineage. The development and variation of coloration in the Mesoamerican cichlids have been detailed by several groups. In particular, Říčan, Musilová, Muška, and Novák (2005) and Říčan, Piálek, Dragová, and Novák (2016) determined homology of pattern and revealed four alternative types of coloration and their ontogeny. In this work, this group posed an “ontogenetic timing hypothesis” proposing heterochronic shifts underlying major transitions in the evolution of the Mesoamerican cichlids. Here, we experimentally test this hypothesis by experimentally altering timing of pigment pattern formation in the convict cichlid Amatitlania nigrofasciata, a member of the Mesoamerican cichlids, via manipulations of thyroid hormone (TH) function. The response of different pigment cell lineages to TH‐perturbations revealed that the transition from larval to juvenile coloration in the convict cichlid is under the control of TH‐signaling. Importantly, hormonally induced changes in the timing of pigment cell lineages’ development resulted in shifts of coloration ontogeny type observed between lineages and led to the appearance of phenotypes mimicking those in phylogenetically close and distant species. Thus, our findings support the hypothesis that simple changes in ontogenetic timing underlies species specific patterns in pigmentation and provide new perspectives for studying the role of endocrine signaling in the evolution of cichlids.

中文翻译：

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异时性在中美洲丽鱼科鱼色素图案演变中的作用的实验证据。

中美洲丽鱼科鱼具有多种多样的色素图案，这些色素可以发挥多种功能，并具有很强的选择性。中美洲丽鱼科鱼的着色的发展和变化已由多个小组详细介绍。特别是，Říčan，Musilová，Muška和Novák（2005）和Říčan，Piálek，Dragová和Novák（2016）确定了图案的同源性，并揭示了四种可供选择的颜色及其本体。在这项工作中，该小组提出了一个“本体发生时间假说”，提出了中美洲丽鱼科鱼进化过程中主要转变的异时性转变。在这里，我们通过实验改变定罪丽鱼科鱼中色素图案形成的时间来实验性地检验这一假设中美洲丽鱼科鱼的成员Amatitlania nigrofasciata通过甲状腺激素（TH）功能的操纵。不同色素细胞谱系对TH扰动的反应表明，在定罪的丽鱼科鱼中，从幼虫到幼稚的过渡是在TH信号的控制下进行的。重要的是，激素诱导的色素细胞谱系发育时间的变化导致了在谱系之间​​观察到的显色本体类型的变化，并导致出现了与系统发育近缘和远缘物种相似的表型。因此，我们的发现支持以下假设：个体发生时间的简单变化是色素沉着中物种特定模式的基础，并为研究内分泌信号在丽鱼科鱼的进化中的作用提供了新的视角。