基于三种分子标记的外伶仃岛石珊瑚系统进化关系研究

以广东省珠海市外伶仃岛地区常见的4属5种石珊瑚为研究对象,对线粒体COI、16S rRNA和ITS三种基因片段数据进行分析,并计算了种间遗传距离。序列分析结果表明5种石珊瑚的COI、16S rRNA基因片段碱基AT含量大于GC含量,而ITS序列碱基AT含量小于GC含量;5种石珊瑚种间的三种基因平均遗传距离分别为0.043、0.134和0.763,所得遗传距离结果存在一定差异。将三种基因串联起来并利用邻位连接法(NJ)、最大似然法(ML)和最小进化法(ME)分别构建了分子系统树。在系统发育树中,科一级的系统进化关系与形态学分类一致,但蜂巢珊瑚科内的分子系统分类结果与形态学分类阐述的遗传进化关系略有差别,说明石珊瑚传统分类可能受骨骼可塑性的影响。研究结果为外伶仃岛石珊瑚的亲缘关系研究提供相关基础数据,并为该地区石珊瑚资源保护奠定理论基础。

Study of phylogenetic relationships of scleractinian from Wailingding Island based on three standard molecular markers

The mitochondrial cytochrome oxidase subunit I (CO I), 16S rRNA, and nuclear ITS genes have been routinely used as standard molecular markers. A total of five species pertaining to four genera of scleractinian, collected from Wailingding Island, Zhuhai City, Guangdong Province, were analyzed by partial sequences, and the genetic distances of these three genes were calculated. The results indicated that the average AT contents of CO I and 16S rRNA gene fragments were obviously higher than the GC contents. However, the average AT content of ITS fragments was obviously less than the GC content. The average genetic distances of the three genes were 0.043, 0.134, and 0.763 from the five species, respectively. The neighbor-joining, maximum-likelihood, and minimum-evolution trees of combined partial sequences of these three genes revealed that the phylogenetic relationships were consistent with the morphological classification in the families. However, the phylogenetic relationships were slightly different from the morphological classification in Faviidae. This result suggested that morphological classification may be limited by coral skeleton plasticity. These findings provide basic data for studying the genetic relationship of Wailingding Island corals and a theoretical basis for resource protection of stone corals in this area.