Segment formation in Annelids: patterns, processes and evolution
Segment formation in Annelids: patterns, processes and evolution
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DOI：
10.1387/ijdb.140148gb
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发表时间：
2014-01-01
影响因子：
0.7
通讯作者：
Balavoine, Guillaume
中科院分区：
文献类型：
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作者：
Balavoine, Guillaume
关于体节起源的争论是后生动物体平面进化研究中的一个中心问题。环节动物是最明显的同色异谱动物，因为躯干的大部分是由相同的解剖单位组成的。在本文中，我总结了各种模式的进化环节动物的同色异谱的身体计划，显示了显着的可进化性，这一特点，也是在节肢动物中发现的。然后，我回顾环节动物树的不同模式的节形成，考虑到这些动物的生活史中发生的各种过程，包括胚胎发生，胚胎后发育，再生和无性繁殖。作为一个例子，发生在环节动物节形成的细胞和遗传水平的变化，我讨论的过程中的关键组的环节动物树的端细胞生长或后添加。我提出了一个全面的定义，端细胞，干细胞，负责顺序段添加。环节动物根据其种类、发育时间和生活史过程产生节段的机制多种多样。未来的一个主要目标将是在整个进化枝的祖先中重建一个祖先过程（或几个祖先过程）。这反过来将提供关键的见解，在目前的辩论祖先两侧分割。
The debate on the origin of segmentation is a central question in the study of body plan evolution in metazoans. Annelids are the most conspicuously metameric animals as most of the trunk is formed of identical anatomical units. In this paper, I summarize the various patterns of evolution of the metameric body plan in annelids, showing the remarkable evolvability of this trait, similar to what is also found in arthropods. I then review the different modes of segment formation in the annelid tree, taking into account the various processes taking place in the life histories of these animals, including embryogenesis, post-embryonic development, regeneration and asexual reproduction. As an example of the variations that occur at the cellular and genetic level in annelid segment formation, I discuss the processes of teloblastic growth or posterior addition in key groups in the annelid tree. I propose a comprehensive definition for the teloblasts, stem cells that are responsible for sequential segment addition. There are a diversity of different mechanisms used in annelids to produce segments depending on the species, the developmental time and also the life history processes of the worm. A major goal for the future will be to reconstitute an ancestral process (or several ancestral processes) in the ancestor of the whole clade. This in turn will provide key insights in the current debate on ancestral bilaterian segmentation.