Development and Evolution of Caecilians (Amphibia: Gymnophiona)

9527681觉醒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。分析骨骼的发育，以及肌肉和神经系统的一些元素，在一个单系谱系，两栖动物目Gymnophiona，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物种的发育情况。一个物种代表一个基本的家庭，具有卵生的、自由生活的幼虫生活史，另外两个物种是胎生的(在母体营养的情况下存活)。一个胎生物种是陆生的，另一个是化石的，它们的发育模式和成虫的形态有很大的不同。因此，可以探讨和分析系统发育史、生活史、栖息地、发育和功能之间的相互作用。将检查头骨的比较发育，以确定结构元素的同源性基础，以及发育的修改程度与上述因素相关的程度。我们将研究牙齿发育的微观结构，以了解胎生形式独特的胎儿牙列的发育和进化。将研究椎骨的发育，以检验重新分割是发育的基本属性的假设，并确定其发生的过程。与骨骼个体发育相关的特定神经和肌肉成分的发育，如颌骨肌肉系统和舌下神经，将被研究。将使用多种技术：免疫组织化学、扫描和透射电子显微镜、透明和染色等。将建立一项圈养饲养线虫的计划，以：(1)提供检查世系繁殖模式多样性的手段；(2)提供关键发育阶段的胚胎用于研究；以及(3)确保在其自然栖息地受到威胁的物种的维持。这是一项综合性的研究，应该会在理解生殖、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