菲律宾海盆线虫群落结构与生物多样性特征

Nematode is the most abundant metazoan on earth, accounting for more than 90% in deep-sea habitats, and plays an important role in deep-sea benthic ecosystem. It is very difficult for taxonomy of deep-sea nematodes because of its small body size and low density in deep-sea sediments. Thus, the study of deep-sea nematodes is very insufficient. Molecular biology is a forceful tool to make up for the shortcomings in traditional morphological taxonomy and has been applied in several studies of deep-sea nematodes. The Philippine Basin is close to China seas and is the strategic choice for deep-sea research of China. At present, a large number of scientific researches have been carried out in this area, but its benthos biodiversity has not yet been studied, despite that its complex environment may raise a high degree of biodiversity. The author found that the Philippine Basin has high species diversity of nematodes at the local scale (a single station), close to that in the Yellow Sea, slightly lower than that in the East China Sea. Accordingly, we propose two main scientific problems in this study: whether the high diversity of nematodes at the local scale in Philippine Basin has the same patterns at the regional scale? What are the main factors driving the species diversity and distribution of nematodes in Philippine Basin? In this project, we will use the traditional morphological and molecular biology techniques to analyze the nematode communities in the Philippine basin, to unmask the community structure and biodiversity of nematodes, to discover new species and hidden species, to reveal its biodiversity characteristics based on the species diversity data and molecular diversity data. This project will provide a reliable background data for the study of deep-sea biodiversity in the Western Pacific Ocean and is expected to lay a foundation for further research on the biogeography and evolution of deep-sea nematodes.

线虫是地球上数量最多的后生动物，在深海底栖环境中占后生动物数量的90%以上。深海线虫由于个体小、丰度低，因此分类鉴定十分困难，对其物种多样性构成无论是在局域还是区域尺度上都知之甚少。菲律宾海盆是我国开展深海研究的战略优选区域，海底具有多样化的生境，但有关线虫的多样性仍然未知。申请人前期研究发现，菲律宾海盆的线虫在局域上具有高物种多样性，与黄海的相近，仅略低于东海陆架海域。由此，本研究提出的主要科学问题是：菲律宾海盆线虫局域上的高多样性是否在区域尺度上有同样的模式？驱动该海域线虫物种多样性及分布的主要因素是什么？本项目拟利用传统形态学和分子生物学技术，解析菲律宾海盆的底栖线虫群落结构组成和分布特点，发现新物种和隐存种，通过物种组成和分子多样性两个层次揭示其多样性特点及其主要驱动因素。本项目将为西太平洋深海生物多样性和分布研究提供翔实可靠的本底资料，为深入研究深海线虫的生物地理学奠定基础。

线虫在深海底栖环境中占后生动物数量的90%以上，但由于深海线虫个体小、丰度低，其分类鉴定十分困难，对其物种多样性构成无论是在局域还是区域尺度上都知之甚少。菲律宾海盆是我国开展深海研究的战略优选区域，但有关线虫的多样性仍然未知。项目按照研究计划执行，包括对菲律宾海盆及邻近海域多个生境的小型底栖生物样品采集、分类鉴定和群落结构分析；对线虫DNA序列提取和扩增，对重要类群进行系统发育研究；对深海沉积物的总DNA进行了提取和高通量测序分析。项目揭示了菲律宾海盆深海小型底栖生物和线虫的群落结构和生物多样性特点，发现西太平洋小型底栖生物平均丰度为（147±93）ind/10 cm2，其中线虫是最优势类群，占比极高（93.56%）；比较不同海区小型底栖生物研究发现，小型底栖生物丰度随着深度的增大呈现降低趋势。对海槽、深海平原、海沟和海山等不同生境的深海沉积物样品进行了高通量测序分析，获得了小型底栖生物的分子多样性数据，发现小型底栖生物和线虫的分布与距离相关。对分选出的线虫进行了分类鉴定，获得了深海线虫物种组成，发现并报道了线虫新物种：Actinonema falciforme Shi & Xu, 2018, Paramphimonhystrella longispicula Shi & Xu, 2017, P. eurystoma Shi & Xu, 2017, Africanema multipapillatum Shi & Xu, 2018。项目发表研究论文5篇，其中SCI收录论文3篇。通过本项目，获得了西太平洋深海小型底栖生物的群落结构和线虫的物种组成情况，为西太平洋深海线虫多样性研究提供一份翔实可靠的本底资料，为未来深入研究深海线虫生物地理格局奠定基础。