8种鲆鲽鱼种间遗传距离与杂交亲和性的相关性分析

Analysis of correlation between pairwise genetic distance of eight flatfishes and hybrid fitness

2005-2008年,先后进行了褐牙鲆♀×夏牙鲆♂、褐牙鲆♀×石鲽♂、褐牙鲆♀×条斑星鲽♂、褐牙鲆♀×大菱鲆♂、大菱鲆♀×条斑星鲽♂的正反交试验,并收集了文献报道的研究资料,包括条斑星鲽×圆斑星鲽、石鲽×星斑川鲽、夏牙鲆×漠斑牙鲆及褐牙鲆×圆斑星鲽的正反交试验结果,对所涉及的8种鲆鲽鱼远缘杂交亲和性进行分析。根据Russell对杂交亲和性的定义,正反交均可行,杂交适合度为1;正反交单向可行,杂交适合度为0.5,正反交均不可行,杂交适合度为0。同时,根据这8种鲆鲽鱼的16S rDNA和COⅠ基因部分序列的差异,估算其种间遗传距离。对8种鲆鲽鱼的种间遗传距离和杂交适合度作相关性分析,二者呈线性负相关(R2=0.81,P<0.01),即杂交的亲和性随种间遗传距离增大而降低。研究表明,鲆鲽鱼的杂交亲和性与其遗传分化程度具有相关性,可以通过种间遗传距离对鲆鲽鱼远缘杂交的亲和性进行预测。

Reciprocal hybrids of olive flounder ♀ （Paralichthys olivaceus ） × summer flounder ♂ （P. dentatus） , olive flounder ♀ （ P. olivaceus） × barfin flounder ♂ （ Verasper moseri） , olive flounder ♀ （ P. olivaceus） × turbot ♂ （Scophthalmus maximus） were performed by artificial fertilization from 2005 to 2008. And data of hybridization on eight flatfish species in previous reports were also collected including barfin flounder （ V. moseri ） × spotted halibut （ V. variegatus ）, stone flounder （ Kareius bicoloratus ） × starry flounder （Platichthys stellatus ） , summer flounder （ P. dentatus ） × southern flounder （ P. lethostigma ） and olive flounder （ P. olivaceus） × spotted halibut （ V. variegatus）. The hybrid compatibilities of interspecific crosses on these eight flatfish species were analyzed. According to Russell＇ s definition, hybrid fitness was scored 1 when the offspring of reciprocal crosses were both viable. The hybrid fitness was scored 0.5 when one direction of reciprocal crosses was viable, and hybrid fitness was scored 0 when the offspring of reciprocal crosses were both inviable. Meanwhile, the ribosomal RNA 16S （16S rRNA） partial sequences and the mitochondrial cytochrome c oxidase subunit Ⅰ （ CO Ⅰ ） partial sequences of the eight flatfishes were obtained and analyzed. Based on combined sequence data of mtDNA 16S rDNA and CO Ⅰ, intrespecific pairwise distances were calculated and a phyogenetic tree was constructed. The relationship between hybrid fitness of the flatfishes and pairwise genetic distances was evaluated and linear correlation existed between the two（ R^2 = 0.♂1, P 〈0.01 ）. The hybrid compatibilities declined with the interspecific genetic distances. Our results suggested that negetive correlation exists between hybrid compatibility and genetic divergence in flatfishes. The hybrid compatibility between different species of flatfishes could be predicted by analysis of interspecific genetic distance. And these results would be good references for further hybrid breeding study in flatfish.