Research on evolution of larval skeleton in sea urchin: Echinometridae

为了了解棘尾科幼虫骨骼的形态多样性，进行了详细的比较研究，其中包括定量形态测量。为了提取骨骼特征是稳定的四臂pluteus阶段，我们比较骨骼特征的两天龄的幼虫（喂养前）和喂养了几天的幼虫。通过这种方法，我们发现五种骨骼特征的身体骨骼是稳定的四臂pluteus。本文将棘胸姬蜂科各种的形态差异归纳为棘、腹后横杆数目的差异和体骨形状的差异，并发现根据这些特征可以从幼虫骨骼上进行种的鉴别。骨骼性状之间存在显著的相关性，如下半身长与棘数之间、上半身长与后腹横竿长之间等。我们还进行了分子系统发育分析的15种Echinometridae，连同一些实验功能方面的幼虫形态。

To understand the morphological variety of larval skeletons within the Echinometridae, a detailed comparative study was performed, which included quantitative morphometry. In order to extract skeletal characters which are stable in four-armed pluteus stage, we compare skeletal characters of two-day-old larvae (prior to feeding) with those of larvae fed for a few days. By this way, we found five skeletal characters of body-skeleton are stable four-armed pluteus. Morphological variations among the Echinometridae species were summarized as the difference in the number of spine and posteroventral transverse rod, and those in the shape of body-skeleton, and we found that based on these characters species can be identified from larval skeleton. Significant correlation can be detected between skeletal characters, such as between lower body length and number of spines, and between upper body length and posteroventral transverse rod length. We have also performed molecular phylogenetic analyses for 15 species of Echinometridae, together with some experiments on functional aspects of larval morphology.