Diaz Raul E, Anderson Christopher V, Baumann Diana P, Kupronis Richard, Jewell David, Piraquive Christina, Kupronis Jill, Winter Kristy, Bertocchini Federica, Trainor Paul A
Department of Biology, La Sierra University, Riverside, California 92515; Natural History Museum of Los Angeles County, Los Angeles, California 90007;
Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912;
Cold Spring Harb Protoc. 2015 Aug 26;2015(10):889-94. doi: 10.1101/pdb.emo087700.
Vertebrate model organisms have facilitated the discovery and exploration of morphogenetic events and developmental pathways that underpin normal and pathological embryological events. In contrast to amniotes such as Mus musculus (Mammalia) and Gallus gallus (Aves), our understanding of early patterning and developmental events in reptiles (particularly nonavians) remains weak. Squamate reptiles (lizards, snakes, and amphisbaenians) comprise approximately one-third of all living amniotes. But studies of early squamate development have been limited because, in most members of this lineage, embryo development at the time of oviposition is very advanced (limb bud stages and older). In many cases, squamates give birth to fully developed offspring. However, in the veiled chameleon (Chamaeleo calyptratus), embryos have progressed only to a primitive pregastrula stage at the time of oviposition. Furthermore, the body plan of the veiled chameleon is highly specialized for climbing in an arboreal environment. It possesses an entire suite of skeletal and soft anatomical modifications, including cranioskeletal ornamentation, lingual anatomy and biomechanics for projection, autopodial clefting for grasping, adaptations for rapid integumental color changes, a prehensile tail with a lack of caudal autotomy, the loss of the tympanum in the middle ear, and the acquisition of turreted eyes. Thus, C. calyptratus is an important model organism for studying the role of ecological niche specialization, as well as genetic and morphological evolution within an adaptive framework. More importantly, this species is easily bred in captivity, with only a small colony (<10 individuals) needed to obtain hundreds of embryos every year.
脊椎动物模式生物有助于发现和探索形态发生事件以及发育途径，这些事件和途径是正常和病理性胚胎学事件的基础。与小家鼠（哺乳纲）和原鸡（鸟纲）等羊膜动物不同，我们对爬行动物（尤其是非鸟类）早期模式形成和发育事件的了解仍然很少。有鳞目爬行动物（蜥蜴、蛇和蚓蜥）约占所有现存羊膜动物的三分之一。但是早期有鳞目动物发育的研究一直很有限，因为在这个谱系的大多数成员中，产卵时胚胎发育已经非常 advanced（肢体芽阶段及更后期）。在许多情况下，有鳞目动物会产出发育完全的后代。然而，在也门变色龙（Chamaeleo calyptratus）中，产卵时胚胎仅发育到原始原肠胚前期阶段。此外，也门变色龙的身体结构高度特化，适合在树栖环境中攀爬。它具有一整套骨骼和软组织的解剖学改变，包括颅骨骨骼装饰、用于投射的舌部解剖结构和生物力学、用于抓握的手足裂、适应快速的体表颜色变化、具有缺乏尾自切功能的可抓握尾巴、中耳鼓膜的缺失以及具炮塔状眼睛的获得。因此，也门变色龙是研究生态位特化作用以及适应性框架内遗传和形态进化的重要模式生物。更重要的是，这种物种很容易在圈养条件下繁殖，每年只需一个小种群（<10 只个体）就能获得数百个胚胎。
