不同地理群体长牡蛎杂交子代的早期生长发育

Larval Growth and Survival of Hybrid Between Different Geographic Populations of Pacific Oyster Crassostrea gigas

本研究以中国、日本、韩国3个地理群体长牡蛎连续选育2代的个体作为亲本,进行了3×3完全双列杂交,建立了3个自交组合和6个杂交组合,分析了各实验组的受精率、孵化率、幼虫阶段的生长和存活、各杂交组子代的杂种优势以及卵源和交配方式对幼虫生长和存活的影响。结果表明,各实验组均有较高的受精与孵化率,除韩国群体♀×韩国群体♂自交组的受精和孵化率明显较低外,其他组之间没有显著差异。在整个幼体阶段,卵源和交配方式对幼虫的生长和存活有显著影响。3个自交组幼虫的生长没有显著差异(P>0.05),6个杂交组幼虫的生长不同程度快于3个自交组,其中中国群体♀×日本群体♂杂交组在整个幼虫阶段生长最快,表现出较大的生长优势,壳高生长的杂种优势率为2.40%～12.53%,其他杂交组也表现不同程度的生长优势。在存活率方面,韩国群体自交组表现出较低的存活率,中国群体♀×日本群体♂和中国群体♀×韩国群体♂2个杂交组的存活率均高于3个自交组,26日龄时的存活率分别为66.63%和61.80%,存活率的杂种优势分别为13.11%～26.52%和40.77%～69.18%,其他杂交组在存活率上没有显示杂种优势。

A 3×3 complete diallel cross was conducted among three populations of Pacific oyster Crassostrea gigas from China（C）,Japan（A）,and Korea（K）,which were successively mass selected for two generation.The fertilization rate,hatching rate,larval survival rate,growth and heterosis at larval stages were compared among the six reciprocal hybrid crosses and three parental crosses,and the effect of both maternal origin and mating strategy on growth and survival was also evaluated.The results indicated that all the nine experimental groups had high fertilization and hatching rates,and did not show significant difference between each other except for parental group KK.Both maternal origin and mating strategy had significant effects on growth and survival throughout the whole larval stage.The growth performances of the larvae of six hybrid crosses were superior to the three parental groups to some extent,showing heterosis in the characteristics of shell height.Especially,the cross CJ had the better heterosis for larval shell height,ranging from 2.40% to 12.53%.The other crosses showed relatively lower heterosis.The larval survival rate of the crosses CJ and CK were higher than that of other hybrid crosses and parental crosses（P0.05）,which reached 66.63% and 61.80% respectively on 26 d.The heterosis of these two hybrid crosses ranged from 13.11% to 26.52% and from 40.77% to 69.18%,respectively.