Development and Evolution of Caecilians (Amphibia: Gymnophiona)

进化生物学中的一个普遍假设是，发育模式的改变可能与生殖模式的改变有关。对单系两栖动物裸子目骨骼的发育以及肌肉和神经系统的一些元素的分析，将检验生殖和发育模式相关的一般假设。将分析代表三个科的三个焦点种的发育情况。一个物种代表一个基础科，具有卵生，自由生活的幼虫生活史，其他两个是胎生的（依靠母体营养生活）。一种胎生物种是陆生的，另一种是穴居的，它们的发育模式，因此，成年形态有很大的不同。因此，系统发展史、生活史、栖息地、发育和功能之间的相互作用可以被探讨和分析。将对颅骨的比较发育进行检查，以确定结构元素同源性的基础，以及发育变化与上述因素相关的程度。牙齿发育的微观结构将被检查，以了解胎生形式的独特胎儿牙列的发育和进化。我们将研究椎骨的发育，以验证再分割是发育的基本特征这一假设，并确定其发生的过程。将研究与骨骼个体发育相关的特定神经和肌肉元素的发育，如颌骨肌肉组织和舌下神经。将采用多种技术：免疫组织化学、扫描和透射电子显微镜、清除和染色等。将建立一个在圈养环境中繁殖幼崽的计划，以便：(1)提供检查谱系中生殖模式多样性的手段；(2)为研究提供关键发育阶段的胚胎；(3)确保在其自然栖息地保护受到威胁的物种。这是一项综合性研究，应该会在探索生殖、发育和进化之间的关系方面取得重大进展

9527681 Wake A general hypothesis in evolutionary biology is that modification of a developmental pattern may be correlated with a change in reproductive mode. Analysis of development of the skeleton, and some elements of the muscular and nervous systems, in a monophyletic lineage, the amphibian Order Gymnophiona, will test the general hypothesis of correlation of reproductive and developmental patterns. Development in three focal species representing three families will be analyzed. One species represents a basal family with an oviparous, free-living larval life history, the other two are viviparous (live-bearing with maternal nutrition). One viviparous species is terrestrial, the other fossorial, and their developmental patterns and, consequently, adult morphologies differ significantly. Consequently, interactions of phylogenetic history, life history, habitat, development and function can be approached and analyzed. Comparative development of the skull will be examined to ascertain the basis of homology of structural elements, and the degree to which modification of development is correlated with the factors mentioned above. The microstructure of tooth development will be examined to understand the development and evolution of the unique fetal dentition of viviparous forms. The development of the vertebrae will be studied to test the hypothesis that resegmentation is a fundamental property of development, and to determine the process by which it occurs. The development of specific neural and muscular elements associated with the skeletal ontogeny, such as the jaw musculature and the hypoglossal nerve, will be studied. A diversity of techniques will be employed: immunohistochemistry, scanning and transmission electron microscopy, clearing and staining, and others. A program t o breed caecilians in captivity will be established in order to: (1) provide means of examining the diversity of reproductive modes in the lineage; (2) provide embryos at crucial developmental stages for study; and (3) assure the maintenance of species threatened in their natural habitats. This is an integrative study that should lead to significant advancement in the search to understand the relationship between reproduction, development and evolution