利用贝壳颜色标记分析皱纹盘鲍苗种繁育中的无意识选择

Unintentional selection during seed culture in the Pacific abalone,Haliotis discus hannai Ino

利用皱纹盘鲍(Haliotis discus hannai)贝壳颜色与摄食饵料相关且贝壳生成后色调不再改变等特点,以幼鲍贝壳顶部摄食底栖硅藻期间形成的褐红色部位的壳长指示它剥离时的壳长,将贝壳颜色用作形态标记,首次在皱纹盘鲍苗种繁育中观察到无意识选择。在投喂人工配合饵料后的第3天与第30天,分别从遗传背景不同的8组样本中取样测量每个幼鲍的褐红色部位壳长,分析每组幼鲍摄食配合饵料后不同时间所测褐红色部位壳长的平均值差异及相关统计学参数。结果表明,其中的7组在第30天时所测剥离时壳长平均值显著或极显著大于同组幼鲍在第3天时的数值;同时,6组样本在30 d时的剥离壳长方差、极差小于3 d时同组样本的数值,所有组合30 d剥离时壳长变异系数等于或小于3 d时同组样本的数值。上述结果提示,在投喂人工配合饵料后的第3天至第30天期间,剥离规格小的幼鲍淘汰率高于剥离规格大者,表明现行皱纹盘鲍育苗工艺对幼鲍在剥离前食用硅藻期间的生长速度进行了一次较高强度的选择,这是苗种管理中无意识选择行为导致的结果。

Selective breeding is one kind of artificial selection which is carried out intentionally. There also exists unintentional process during intentional selective breeding. The aim of this study was to determine if there existed unintentional selection on Original Shell Length （OSL, as indicated by brown shell color） during subsequent seed culture in the Pacific abalone （Haliotis discus hannai Ino）. As the Pacific abalone juveniles produce brown shells during their early stage when they feed on benthic diatom right after metamorphism but their shell color changes to green when fed with artificial diets during subsequent seed culture stage, we compared the average OSL on the 3rd （the beginning shell length, BSL） and 30th （the final shell length, FSL） day after feeding with the artificial diets. In 7 out of 8 groups of Pacific abalone with identical genetic origin, the average FSL was significantly larger than average BSL. Meanwhile, the standard deviation and range of the FSL were smaller than those of the corresponding BSL in six groups. The coefficients of variation of all the eight groups of FSL were smaller than those of BSL. Obviously, more juveniles with small OSL were unintentionally lost during the seed culture stage.