嵊泗列岛海域三种贻贝贝体框架特征的差异

VARIATIONS IN SHELL FRAME CHARACTERISTIC AMONG THREE SPECIES OF MYTILUS IN SHENGSI WATERS OF THE EAST CHINA SEA

以壳长SL、壳宽SW、壳高SH(BD)、OA(壳顶至韧带末端的直线距离)、OB(壳顶至壳背面最高点的直线距离)、OC(壳顶至壳后端最远点的直线距离)、OD(壳顶至壳高性状在腹缘的落点的直线距离)、AB(韧带末端至壳背缘最高点的直线距离)、BC(壳背缘最高点至壳后端最远点的直线距离)、CD(壳后端最远点至壳高性状在腹缘的落点的直线距离)为贝体框架变量,采用多元分析方法系统比较了嵊泗列岛海域厚壳贻贝、紫贻贝和"杂交贻贝"贝体框架特征的差异,结果表明:(1)在所涉9项贝体框架特征指标中,紫贻贝与厚壳贻贝间无显著差异的指标仅为L5(OC/SL)和L7(AB/SL)(P>0.05),而"杂交贻贝"各项指标则均与厚壳贻贝和紫贻贝具显著差异(P<0.05),厚壳贻贝和紫贻贝变异系数大于10%的指标均仅为L7(AB/SL),而"杂交贻贝"则仅为L3(OA/SL);(2)厚壳贻贝与紫贻贝间的欧氏距离最短(P<0.05),仅为0.160;厚壳贻贝与"杂交贻贝"间和紫贻贝与"杂交贻贝"间的欧氏距离相近(P>0.05),分别为0.452和0.418;(3)经主成分分析,提取到的3个特征值均大于1的主成分,累计贡献率达82.928%,其中第一主成分、第二主成分、第三主成分可依次归为与滤食功能区水平剖面占比相关的贝体框架因子,与消化功能区水平剖面占比相关的贝体框架因子,和与消化功能区垂直剖面占比相关的贝体框架因子,通过第一主成分仅能较清晰地区分厚壳贻贝和"杂交贻贝";(4)采用逐步判别法,以判别贡献率较大的L1(SW/SL)、L3(OA/SL)、L4(OB/SL)、L5(OC/SL)、L6(OD/SL)和L7(AB/SL)为自变量,所建Fisher分类函数方程组可较清晰区分厚壳贻贝、紫贻贝和"杂交贻贝",三者的判别准确率依次为94.6%、94.6%和100%,综合判别准确率为96.4%。

We set nine morphological indexes as framework variables, including shell length(SL), shell height(SH), straight-line distance from umbo to ligament-end(OA), straight-line distance from umbo to the rear-most point in posterior(OC), straight-line distance from umbo to the foothold of SH in ventral margin, straight-line distance from ligament-end to the top of dorsal margin(AB), straight-line distance from the top of dorsal margin to rear-most point in posterior(BC), and rear-most point in posterior to the foothold of SH in ventral margin(CD), with which multivariate analysis was performed to compare difference in frame characteristics among M. coruscus, M. edulis, and the cross-bred mussel. The results indicate that:(1) among the nine indexes, only indexes L5(OC/SL) and L7(AB/SL) showed no significant difference between M. coruscus and M. edulis. However, all involving indexes of the cross-bred mussel showed significant difference from those of M. coruscus and M. edulis. Only the variable coefficient of index L7 of M. coruscus and M. edulis, and L3(OA/SL) of the cross-bred were greater than 10%;(2) the Euclidean distance between M. coruscus and M. edulis was 0.160, the shortest, whereas those between M. coruscus and the cross-bred, M. edulis and the cross-bred were 0.452 and 0.418, respectively, very close;(3) the three principal component whose eigenvalue was over 1 was obtained, and the maximum accumulative contribution rate reached 82.928%. The first, second, and third principal components were ascribed as the factors related to the proportion of horizontal section of filter-feeding function zone, the proportion of horizontal section, and the vertical section of digestive function zone, respectively. M. coruscus and the cross-bred mussel can be distinguished by the first principal component;(4) with the Fisher classification function that built by stepwise method, we selected L1(SW/SL), L3(OA/SL), L4(OB/SL), L5, L6(OD/SL), and L7 as variables, with which we could identify M. coruscus, M. edulis, and the cross-bred mussel successfully in rate of 94.6%, 94.6%, and 100%, respectively, or the overall rate at 96.4%.