菲律宾蛤仔福建与广东群体的双列杂交

The diallel cross of Manila clam (Ruditapes philippinarum) populations from Fujian and Guangdong Provinces

2015年9月–12月,以菲律宾蛤仔福建养殖群体和广东野生群体子一代为亲本,开展了双列杂交实验,建立了两个自交组和两个杂交组,研究了杂交子代幼虫和稚贝的生长与存活的杂种优势。结果显示,各实验组均有较高的受精率和孵化率,但无显著差异。总体上,幼虫期的生长受母体效应影响显著,稚贝期的生长杂交效应主要受交配方式影响。相反,幼虫期的存活受配对方式影响最显著,稚贝期的存活受卵源影响显著。在幼虫期,杂交组与自交组在生长和存活方面差异不显著。在稚贝期,生长表现出明显的杂种优势,壳长和壳高在30日龄以后,正反交组的平均生长速率显著快于自交组。在40日龄时,壳高和壳长总杂交优势值达到最大,分别为25.64和27.00。这可能是因为杂种优势的表达具有时期差异性。在幼虫期,福建自交组表现出最高的存活率,为36.45%±1.85%;稚贝期,广东自交组存活率最高,为52.27%±2.13%。在幼虫期和稚贝期的存活率方面,未观测到杂种优势,这可能是由于两个杂交亲本群体与存活相关的基因频率无差异或者检测次数较少所致。

In 2015, from Septemper to December, a diallel cross was conducted using two populations of Manila clam Ruditapes philippenarum from cultured Fujian stock and wild Guangdong stock which was F1 progeny. The growth, survival rate and heterosis at larval and juvenile periods were compared among the two reciprocal hybrid crosses and two parental crosses. The results indicated that all the four experimental groups had high fertilization and hatching rates, and did not show significant difference between each other. Totally, at larval period, maternal origin had significant effect on growth. While mating strategy was the major factor for growth hybrid effect during juvenile. In contrast, at larval period, mating strategy had significant effect on survival, while maternal origin was the major factor for survival during juvenile. This showed that gamete incompatibility and embryonic development disorders did not exist in interspecific hybridization between different geographical populations of R. philippenarum. At larval period, no growth or survival heteiosis was observed between two hybrid crosses and the two parental groups. In contrast, at juvenile period, the growth performances of two hybrid crosses were superior to the two parental groups, showing heteiosis in the characteristics of shell height and shell length after 30 days of age.Especially, at 40 days of age, heterosis values of shell height and shell length reached maximum, which were 25.64 and 27.00, respectively. This perhaps attributed to development difference of expression of heterosis. For survival rate, at larval period, the Fujian parental cross had the best performance which was 36.45%±1.85%. And the juvenile survival rate of the Guangdong parental cross was 52.27%±2.13%, which was higher than other three experimental crosses. In total, survival heterosis was not observed during the study. This was attributed to the fact that survival-related gene frequency of two geographic parental populations had no difference or detection was less often.