紫贻贝与厚壳贻贝杂交子代生长和存活比较

Comparison of growth and survival among the hybrid offspring of Mytilus galloprovincialis and M. coruscus from laboratory crosses

利用辽宁大连的紫贻贝(Mytilus galloprovincialis)与福建宁德的厚壳贻贝(M.coruscus)为亲本,采用2×2双列杂交设计,构建了紫贻贝自交组(M.galloprovincialis♀×M.galloprovincialis♂)、正交组(M.gallopro-vincialis♀×M.coruscus♂)、反交组(M.coruscus♀×M.galloprovincialis♂)与厚壳贻贝自交组(M.coruscus♀×M.coruscus♂)4个遗传组合,比较分析了受精率、孵化率、子代的成活率、生长数据等,探讨了紫贻贝与厚壳贻贝种间杂交的可行性,同时为贻贝良种选育提供参考。结果表明,自交组与反交组的受精强度具有不对称性,正交组与自交组受精率无差异,反交组的受精率及孵化率显著低于正交组与自交组(P<0.05),且浮游幼虫不能正常存活;正交组子代具有生长优势,第9、11、13天的浮游幼虫及第78天的稚贝壳长均显著大于自交组(P<0.05);正交组与紫贻贝自交组在整个幼虫阶段存活率无显著差异,在壳顶幼虫期显著高于厚壳贻贝自交组(P<0.05)。

This study was designed to clarify the feasibility of interspecific hybridization between two commercially im-portant mussel species,Mytilus galloprovincialis and M.coruscus,for which a diallel cross was conducted with 3 repli-cates using the broodstock of M.galloprovincialis from Dalian,Liaoning,and M.coruscus from Ningde,Fujian.Two cross groups,i.e.,M.galloprovincialis♀×M.coruscus♂and M.coruscus♀×M.galloprovincialis♂,were established,along with two purebred groups(M.galloprovincialis♀×M.galloprovincialis♂,M.coruscus♀×M.coruscus♂)used as controls.Subsequently,the rates of fertilization,hatching,survival,and growth of all the offspring were monitored and evaluated to compare the development and growth among the four groups.Results demonstrated that the fertilization rate was remarkably asymmetric between the two cross groups.A mean fertilization rate of 88.87%was observed in the cross group M.galloprovincialis♀×M.coruscus♂,which was not significantly different compared with that of the two purebred groups.The fertilization and hatching rates of the cross group M.coruscus♀×M.galloprovincialis♂were sig-nificantly lower than those of all the other groups(P<0.05),ultimately resulting in the lack of offspring.The offspring derived from the cross group M.galloprovincialis♀×M.coruscus♂exhibited a remarkable advantage in growth,as evi-denced by the shell lengths of the planktonic larvae on days 9,11,and 13 and the juvenile on day 78,which were sig-nificantly larger than those of the purebred groups(P<0.05).The survival rate of the cross group M.galloprovincial-is♀×M.coruscus♂showed no significant difference compared with the purebred group M.galloprovincialis♀×M.gal-loprovincialis♂during the planktonic larval stage;however,it was significantly higher than that of the purebred group M.coruscus♀×M.coruscus♂(P<0.05).These results provide valuable information that can be used in mussel breeding programs in the future.