PDF(Pubmed)
Abstract：
Intense environmental pressures can yield both regressive and constructive traits through complex evolutionary mechanisms. Although regression is well-studied, the biological bases of constructive features are less well understood. Cave-dwelling Astyanax fish harbor prolific extraoral taste buds on their heads, which are absent in conspecific surface-dwellers. Here, we present novel ontogenetic data demonstrating extraoral taste buds appear gradually and late in life history. This appearance is similar but non-identical in different cavefish populations, where patterning has evolved to permit taste bud re-specification across the endoderm-ectoderm germ layer boundary. Quantitative genetic analyses revealed that spatially distinct taste buds on the head are primarily mediated by two different cave-dominant loci. While the precise function of this late expansion on to the head is unknown, the appearance of extraoral taste buds coincides with a dietary shift from live-foods to bat guano, suggesting an adaptive mechanism to detect nutrition in food-starved caves. This work provides fundamental insight to a constructive evolutionary feature, arising late in life history, promising a new window into unresolved features of vertebrate sensory organ development.
摘要：
强烈的环境压力可以通过复杂的进化机制产生回归和建设性特征。虽然回归研究得很好，构造特征的生物学基础不太清楚。居住在洞穴中的Astyanax鱼头上有丰富的口外味蕾，在同种表面居民中不存在。这里,我们提供了新的个体发育数据，表明口外味蕾在生活史上逐渐和晚期出现。在不同的洞穴鱼种群中，这种外观相似但不相同，图案已经演变为允许在内胚层-外胚层胚层边界上重新指定味蕾。定量遗传分析显示，头部空间上不同的味蕾主要由两个不同的洞穴优势基因座介导。虽然这种晚期扩展到头部的确切功能是未知的，口外味蕾的出现与从活食到蝙蝠鸟粪的饮食转变相吻合，提出了一种适应性机制来检测食物匮乏的洞穴中的营养。这项工作为建设性的进化特征提供了基本的见解，出现在生活史的后期，有望为脊椎动物感觉器官发育的未解决特征提供新窗口。
