一個給定物種中具有相同基因組的植物或動物卻能發(fā)育成相差迥異的形式，它取決于環(huán)境條件,，這個現(xiàn)象被稱為“發(fā)育彈性”，該現(xiàn)象在自然界很普遍,，但卻很少從基因和分子角度對其進行描述。
圖片來源： M. Herrmann
對線蟲Pristionchus pacificus的一種新的捕食性特征（即嘴中額外的牙齒狀結構的形成使得它們能夠以真菌為食以及在種群密度過大時以其他線蟲為食）所做的一項研究表明,，它是由控制第四期幼蟲（dauer larva）形成的同一內分泌體系調控的,。（第四期幼蟲狀態(tài)相當于線蟲的休眠期。）源自關鍵信號作用通道這種性狀功能變化（稱之為“co-options”或“exaptations”）的“彈性”可能有助于形態(tài)新穎性的形成,。（生物谷Bioon.com）
生物谷推薦原文出處：
Nature doi:10.1038/nature09164
Co-option of the hormone-signalling module dafachronic acid–DAF-12 in nematode evolution
Gilberto Bento,Akira Ogawa& Ralf J. Sommer
Morphological novelties are lineage-specific traits that serve new functions1, 2. Developmental polyphenisms have been proposed to be facilitators of phenotypic evolution, but little is known about the interplay between the associated genetic and environmental factors3, 4, 5, 6, 7, 8, 9, 10, 11. Here, we study two alternative morphologies in the mouth of the nematode Pristionchus pacificus and the formation of teeth-like structures that are associated with bacteriovorous feeding and predatory behaviour on fungi and other worms12, 13, 14, 15, 16. These teeth-like denticles represent an evolutionary novelty, which is restricted to some members of the nematode family Diplogastridae but is absent from Caenorhabditis elegans and related nematodes14. We show that the mouth dimorphism is a polyphenism that is controlled by starvation and the co-option of an endocrine switch mechanism. Mutations in the nuclear hormone receptor DAF-12 and application of its ligand, the sterol hormone dafachronic acid, strongly influence this switch mechanism. The dafachronic acid–DAF-12 module has been shown to control the formation of arrested dauer larvae in both C. elegans and P. pacificus, as well as related life-history decisions in distantly related nematodes17, 18, 19, 20. The comparison of dauer formation and mouth morphology switch reveals that different thresholds of dafachronic acid signalling provide specificity. This study shows how hormonal signalling acts by coupling environmental change and genetic regulation and identifies dafachronic acid as a key hormone in nematode evolution.
