Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätstrasse 10, 78457, Konstanz, Germany.
Mol Ecol. 2013 Sep;22(17):4516-31. doi: 10.1111/mec.12417. Epub 2013 Aug 19.
Adaptive phenotypic plasticity, the ability of an organism to change its phenotype to match local environments, is increasingly recognized for its contribution to evolution. However, few empirical studies have explored the molecular basis of plastic traits. The East African cichlid fish Astatoreochromis alluaudi displays adaptive phenotypic plasticity in its pharyngeal jaw apparatus, a structure that is widely seen as an evolutionary key innovation that has contributed to the remarkable diversity of cichlid fishes. It has previously been shown that in response to different diets, the pharyngeal jaws change their size, shape and dentition: hard diets induce an adaptive robust molariform tooth phenotype with short jaws and strong internal bone structures, while soft diets induce a gracile papilliform tooth phenotype with elongated jaws and slender internal bone structures. To gain insight into the molecular underpinnings of these adaptations and enable future investigations of the role that phenotypic plasticity plays during the formation of adaptive radiations, the transcriptomes of the two divergent jaw phenotypes were examined. Our study identified a total of 187 genes whose expression differs in response to hard and soft diets, including immediate early genes, extracellular matrix genes and inflammatory factors. Transcriptome results are interpreted in light of expression of candidate genes-markers for tooth size and shape, bone cells and mechanically sensitive pathways. This study opens up new avenues of research at new levels of biological organization into the roles of phenotypic plasticity during speciation and radiation of cichlid fishes.
适应性表型可塑性，即生物体改变其表型以适应局部环境的能力，其对进化的贡献正日益得到认可。然而，很少有实证研究探索可塑性特征的分子基础。东非慈鲷鱼 Astatoreochromis alluaudi 在其咽颚器官中表现出适应性表型可塑性，咽颚器官是一种被广泛认为是进化关键创新的结构，为慈鲷鱼类的显著多样性做出了贡献。此前的研究表明，在不同的饮食条件下，咽颚会改变其大小、形状和齿列：硬食会诱导出适应性的强壮臼齿状牙齿表型，具有短颚和强壮的内部骨骼结构，而软食则会诱导出纤细的乳突状牙齿表型，具有长颚和细长的内部骨骼结构。为了深入了解这些适应性的分子基础，并为未来研究表型可塑性在适应性辐射形成过程中的作用提供参考，研究人员对两种不同的颚部表型的转录组进行了研究。我们的研究共鉴定出了 187 个基因，这些基因的表达因硬食和软食而不同，包括即时早期基因、细胞外基质基因和炎症因子。转录组结果与候选基因——牙齿大小和形状、骨细胞和机械敏感途径的表达进行了解释。这项研究为在慈鲷鱼类的物种形成和辐射过程中，研究表型可塑性的作用开辟了新的研究途径，并深入到了新的生物学组织层次。
