文昌鱼秦皇岛、青岛和厦门地理种群形态特征的分化

Divergence in Qinhuangdao, Qingdao and Xiamen Geographical Populations of Amphioxus (Branchiostoma belcheri Gray) Based on Morphological Characters Analysis

把分别采自秦皇岛、青岛和厦门(各25尾)的文昌鱼种群的形态特征分为计数性状8个和计量性状10个,然后对18个形态特征进行ANOVA、聚类和主成分分析。结果表明:3地种群全长、体高和背腹鳍条数等18个形态特征的平均值均存在显著差异(P<0·05),且种群间的变异大于种群内。进一步比较秦皇岛和青岛种群,除在口笠触须、背鳍条数、腹鳍条数和肌节总数4个特征较为相似外,其余14个特征均存在显著差异(P<0·05);而青岛和厦门种群在全长、体高、腹孔肛门间肌节数、生殖腺数、吻鳍高、背鳍高、上尾鳍高等7个特征上更为相似(P>0·05);此外,秦皇岛和厦门种群在腹鳍高、上尾鳍长和高、下尾鳍长和高等5个特征上存在相似性(P>0·05)。聚类分析结果表明,75个样本明显分成两个类群:第二类群主要由厦门样本构成,而第一类群则主要由秦皇岛和青岛样本构成。由前3个主成分分析结果表明,所有样本可大致分为3个类群:秦皇岛、青岛和厦门类群。其中来自厦门的个体聚成一个明显的独立类群,而来自秦皇岛和青岛的样本在主成分分析图上则存在一定的交叉和重叠。总之,厦门地理种群分化最为明显,而秦皇岛和青岛种群在总体分化的趋势下,个体间形态特征仍存在相似性。

The multivariate variance analysis, cluster analysis and principal component analysis (PCA) were conducted based on 18 morphological characters that including 8 numerical characters and 10 metric characters in amphioxus populations from Qinhuangdao (QHD), Qingdao (QD) and Xiamen (XM) with 25 samples, respectively. The results showed that significant difference (P<0.05) in means of 18 morphological characters such as length of body, height of body, number of dorsal/ventral septa etc., existed among 3 different amphioxus populations, and there were great variance among populations than within population. Multiple comparisons of the LSD of morphological characters of 3 amphioxus populations showed that QHD and QD populations existed significant difference (P<0.05) in 14 morphological characters, expected in number of buccal cirri, number of dorsal septa, number of ventral septa and number of total myotomes. QD and XM populations were no significant difference (P>0.05) in 7 morphological characters such as length of body, height of body, number of myotomes in middle, number of gonads, height of rostral fin, height of dorsal fin and height of supra-caudal fin. QHD and XM populations were similar (P>0.05) in 5 morphological characters, e.g. height of ventral fin, length and height of supra-caudal fin, length and height of sub-caudal fin. In the results of cluster analysis suggested that all of the 75 samples were divided into two clusters clearly. ClusterⅡ were mainly maded of 21 samples from XM population, while QHD samples and QD samples were pooled into clusterⅠ. The result of the first three principal components from PCA showed that there were about 3 groups gathered by the all samples, QHD, QD and XM groups. All samples from XM population were pooled into one independent group; QHD and QD groups were pooled with some individual swarmed and crossed each other showed from the graph of PCA. It is inferred that XM geographical population had been great genetic differentiation in morphological characters, and amphioxus populations from QHD and QD also had genetic divergence on the whole while similar in some morphological characters.