A sensory deficit both at the individual and at the species level can be compensated by increased acuity in other senses. The loss of vision in blind cavefish, Astyanax mexicanus, appears to be partially counterbalanced by enhanced chemosensory perception. Whether such improvement also involves adaptive changes in chemosensory receptor repertoires was unknown. The typical bitter taste receptor repertoire of teleost fish is reported as 3-5 genes, much smaller than that of many terrestrial species. Interestingly, several fish species, for example, mudskipper, have evolved a terrestrial lifestyle, but again it was unknown, whether this change in habitat is reflected in the size of gustatory receptor repertoires. We have searched the genomes of 15 fish species and performed a thorough phylogenetic analysis to delineate their bitter taste receptor repertoires. We report no adaptation for 4 mudskipper species, which exhibit 3-4 bitter taste receptor genes, and thus a typical teleost repertoire, shaped by few gene losses and minor gene duplications from an ancestral repertoire of 4 genes. However, and in sharp contrast to all other teleost fish species analyzed, blind cavefish possess more than 20 intact bitter taste receptors and several pseudogenes, rivaling the complexity of the human bitter taste receptor repertoire. The gene duplications giving rise to the current cavefish bitter taste receptor repertoire appear to have occurred well before the loss of vision, consistent with this increase in repertoire size constituting a preadaptive trait that conceivably could compensate to some extent for the lack of visual cues.

中文翻译：

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盲孔鱼中苦味受体的大规模扩展。

其他意义上的敏锐度可以弥补个体和物种的感官缺陷。盲目石斑鱼Astyanax mexicanus的视力丧失似乎可以通过增强的化学感觉感知来部分抵消。这种改善是否还涉及化学感觉受体组成的适应性改变尚不清楚。据报道，硬骨鱼的典型苦味受体库为3-5个基因，远小于许多陆生物种的苦味受体库。有趣的是，几种鱼类（例如，sk鱼）已经进化成陆地上的生活方式，但是再次未知的是，栖息地的这种变化是否反映在味觉受体库的大小上。我们已经搜索了15种鱼类的基因组，并进行了彻底的系统发育分析，以描述其苦味受体的组成。我们报告没有适应适应4个mud鱼物种，这些物种表现出3-4个苦味受体基因，因此是典型的硬骨鱼目，几乎没有基因损失，而祖先的4个基因则有少量基因重复。然而，与分析的所有其他硬骨鱼种类形成鲜明对比的是，盲目的洞穴鱼拥有20多种完整的苦味受体和几种假基因，可与人类苦味受体库的复杂性相媲美。造成当前洞穴鱼苦味受体库的基因重复似乎早在视力丧失之前就已发生，