Collaborative Research: Segment development in select trilobite species - glimpses into the evolution of body organization in an early arthropod clade

合作研究：特定三叶虫物种的节段发育——一窥早期节肢动物进化枝的身体组织进化

• 批准号: 0616574
• 负责人: Nigel Hughes
• 金额: $ 17.8万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0616574&HistoricalAwards=false
• 关键词: Collaborative; Research; Segment; development; select

Collaborative Research: Segment development in select trilobite species"glimpses into the evolution of body organization in an early arthropod cladeNigel C. Hughes, U. California Riverside, EAR-0616574H. David Sheets, Canisius College, EAR-0616726ABSTRACTRecent advances in development genetics and cell biology are revolutionizing understanding of the developmental basis of animal form. The mechanisms by which body segments, the modules from which arthropod bodies are constructed, are specified and differentiated are becoming known across members of the crown group Euarthropoda, which contains all living arthropod groups. The extinct clade Trilobita also belonged to the Euarthropoda but with respect to the control of its body patterning did not depart markedly from what was apparently the ancestral euarthropod condition. Hence the exceptionally well-preserved record of trilobite ontogeny and phylogeny recorded in early Paleozoic rocks assumes special significance as a chronicle of early euarthropod experiments in body patterning. The Silurian aulacopleurid trilobite Aulacopleura konincki has proved to be an exceptional model system for exploring how trilobites controlled the number of segments assigned to the trunk region and the controls on their allocation of trunk segments to the thorax or to the pygidium - the terminal shield consisting of conjoined segments. Aulacopleura konincki shows unusual variation in the number of thoracic segments during the mature, segment-invariant growth phase. Previous work by the PI Hughes has tested hypotheses concerning control of the mature segment number, with results favoring the Early Determination Hypothesis (EDH), in which the ultimate number of segments was determined early in ontogeny. This suggests highly regulated developmental control among early arthropods, even those apparently plastic in aspects of body construction. However, determining the controls of development in a species 435 million years old presents a severe challenge. This project will explore ontogenetic trajectories of sclerite shape change to provide additional tests of the EDH, based primarily on the pattern of shape change in the cephalic (head) region that is independent of trunk segmentation. The paleoenvironmental context of changes in segmentation will also be explored through a geochemical proxy approach. The project will involve graduate student training and extensive collaboration with scientists in the Czech Republic, Italy, and Canada, and will involve the development of new statistical software that will be made freely available to the scientific community.

合作研究：精选三叶虫物种的节段发育“对早期节肢动物分支的身体组织进化一瞥奈杰尔·C.休斯，加州大学河滨分校，EAR-0616574H。发育遗传学和细胞生物学的最新进展正在彻底改变人们对动物形态发育基础的理解。在包含所有活的节肢动物类群的冠类群Euararpoda的成员中，身体节段(构成节肢动物身体的模块)被指定和区分的机制正在变得已知。已灭绝的三叶虫也属于真节肢动物，但就其身体的控制而言，花纹并没有明显偏离其祖先的真节肢动物的状况。因此，在早古生代岩石中记录的保存异常完好的三叶虫个体发育和系统发育记录，作为早期真节肢动物身体模式实验的编年史，具有特殊的意义。志留纪的三叶虫Aulaco pleura konincki已被证明是一个特殊的模式系统，可以用来研究三叶虫如何控制分配给躯干区域的节段的数量，以及控制它们将主干节段分配到胸腔或肘部--由连接的节段组成的终端盾牌。在成熟的、节段不变的生长阶段，Aulaco pleura konincki在胸节的数量上表现出异常的变化。Pi Hughes夫妇之前的工作已经测试了与成熟片段数量控制有关的假说，结果支持早期确定假说(EDH)，即最终片段数量是在个体发育早期确定的。这表明早期节肢动物的发育受到高度调控，即使是那些在身体结构方面明显可塑的节肢动物也是如此。然而，确定一个4.35亿年前物种的发育控制是一个严峻的挑战。该项目将探索硬骨形状变化的个体发生轨迹，以提供额外的EDH测试，主要基于独立于躯干分段的头部(头部)区域的形状变化模式。还将通过地球化学替代方法探索分段变化的古环境背景。该项目将涉及研究生培训以及与捷克共和国、意大利和加拿大科学家的广泛合作，并将涉及开发新的统计软件，供科学界免费使用。