凡纳滨对虾(俗称南美白对虾)在许多亚洲国家是重要的对虾养殖种类。本研究的目的是筛选微卫星标记选择生长速度快的凡纳滨对虾养殖种群从而建立选育计划的基础群体。研究材料是由第二代亲虾繁殖产生的虾苗在相同条件下培养5个月的生长期对虾。从研究对象中分别选择90尾幼虾建成生长速度慢、生长速度中等、生长速度快的群体,10个微卫星标记用于研究遗传多样性,并研究选择育种的遗传进展。利用样品中筛选出10个多态性标记位点(M1-M10),其中,M8位点的多态性最高,M7的多态性最低,在快速生长组检测到多态性M5位点。快速生长组和中速生长组的遗传距离最大(0.481),中速生长组和慢速生长组之间遗传距离最短(0.098);因此,中速生长组和慢速生长组之间的遗传一致性最大(0.946),快速生长组和中速生长组之间的遗传一致性最小(0.667)。根据Nei的遗传距离和非加权配对组算术平均(UPGMA)聚类方法,将3个不同生长组聚类为两大类,第一类为中速生长组和慢速生长组,第二类为快速生长组。生长速度的选择反应和现实遗传力为分别增长11.55%和31.26%。因此,这套微卫星标记会在对虾育种方案提供了一个有用的工具。

本研究的目的为评估大菱鲆在低温条件下生长性状的遗传力,并分析体重和体长之间的相关性.试验选取来自25个全同胞和半同胞家系的536尾大菱鲆进行低温生长试验.从大菱鲆233日龄到323日龄,在90天的生长周期中对个体每18天采集一次体重、体长数据.在个体动物模型中利用非求导约束最大似然法(DFREML)估计体重和体长的遗传力和这两个性状之间的相关性.结果表明,在10.5-12 ℃的低温条件下,25个家系的特定生长率为0.75±0.11～1.05±0.14.估计的体重和体长的遗传力分别为0.32±0.04和0.47±0.06.体重表现为中等遗传力(0.2-0.4),体长表现为高等遗传力(> 0.45),这表明以体重和体长作为选育性状是可行的.此外,体重和体长对于大规模的良种选育是很有潜力的.体重和体长之间的遗传相关和表型相关分别为0.95±0.01和0.91±0.01(P< 0.01).体重和体长之间的显著相关表明,在育种规划中通过间接选育可以取得很好效果的.

The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp (Litopenaeus vannamei) for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids, the heterosis ranged from -11.37% (UA1×UA2) to 20.53% (UA3×SIN) with an average of 0.953%. The results showed that more than half of the hybrids (51.85%) have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero (P<0.05). The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.

中国对虾低温耐受性一直备受关注,因为低温耐受性差不仅大大缩短了中国对虾的生长期,而且会影响其越冬的安全性。本研究选用88个半同胞家系首次对中国对虾在低温下生长及耐低温性状的遗传力进行评估,以期为中国对虾良种选育提供数据支持。中国对虾在常温和低温下体重性状均为中等遗传力(分别为0.1580±0.3075和0.1320±0.0269),变异系数约为21%,均表明中国对虾体重性状具有较大的选育潜力。中国对虾耐低温性状的遗传力为0.0192±0.0235,与0无显著差异(P>0.05),为低等遗传力性状。相关分析表明中国对虾耐低温性状与体重性状间的遗传相关微弱。因此,我们需要进一步的研究来获得更为精准的中国对虾耐低温遗传力以及中国对虾各性状间的遗传相关系数,从而推动中国对虾良种选育进程。

The objective of this study was to estimate genetic parameters of body width (BW) to body length (BL) ratio (BW/BL) and of body weight traits (BWT) in turbot, and to elucidate the genetic mechanism of the two traits during ontogeny by dynamic genetic analysis. From 3 to 27 months, BW, BL and BWT of each communally stocked fish were measured every 3 months. The BW/BL ratio was measured at different sampling ages. A two-trait animal model was used for genetic evaluation of traits. The results showed that the heritability values of BW/BL ratio ranged from 0.216 8 to 0.314 8, corresponding to moderate heritability. The BWT heritability values ranged from 0.270 2 to 0.347 9 corresponding to moderate heritability. The heritability of BW/BL ratio was lower than that of BWT, except at 3 months of age. Genetic correlation between BW/BL ratio and BWT decreased throughout the measurement period. Genetic correlations were higher than the phenotypic correlations. The current results for estimating genetic parameters demonstrate that the BW/BL ratio could be used as a phenotypic marker of fast-growing turbot, and the BW/BL ratio and BWT could be improved simultaneously through selective breeding.

Heritability and genetic and phenotypic correlations were estimated for juvenile growth traits of Pacific abalone Haliotis discus hannai Ino.The estimates were calculated from shell length and shell width measurements on progeny resulting from 12 half-sib families and 36 full-sib families obtained using artificial fertilization of mating three females to each male.The measurements were taken at 10, 20 and 30 d after fertilization.It was found that heritability estimates based on sire component ranged from 0.23 to 0.36 for shell length and 0.21 to 0.32 for shell width.Heritability estimates from dam component were larger than those from sire component at three ages, indicating presence of maternal effects, non-additive genetic effects and common environmental effects.Phenotypic correlations were significant at three ages (P<0.05), with values of 0.92, 0.93 and 0.92, respectively.Genetic correlations from the paternal half-sib correlation analysis were highly positive at three ages, with values of 0.50, 0.78 and 0.81, respectively.The results suggest that selective breeding is an effective approach to improving growth traits of Pacific abalone stocks.

The complete diallel cross design was employed to estimate the genetic parameters of the growth of Japanese flounder (Paralichthys olivaceus). A total of 60 full-sib families were cultivated and two growth-related traits, body weight (BW) and body length (BL), were examined at average 2, 3 and 8 months of age respectively, with 1 800 individuals measured in each age group (30 per family). Based on the additive-dominance-maternal-effect genetic analysis model, the restricted maximum likelihood approach was used to estimate various (co)variance components. The results showed that narrow-sense heritability estimates of BW and BL were respectively:0.29±0.01 and 0.22±0.02 at 2 months of age, 0.32±0.02 and 0.30±0.04 at 3 months of age, 0.48±0.04 and 0.40±0.05 at 8 months of age; broad-sense heritability estimates were respectively:0.44±0.02 and 0.54±0.04 at 2 months of age, 0.35±0.01 and 0.36±0.03 at 3 months of age, 0.49±0.03 and 0.45±0.04. All heritabilities were statistically significant (P <0.05). Additive genetic correlations between BW and BL at 2, 3 and 8 months of age were consistently positive and highly significant (P <0.01):0.93±0.02, 0.95±0.03 and 0.92±0.03 respectively. Maternal effect was significant (P <0.05) only at 2 months of age, and was not detected at 3 and 8 months of age. According to the heritability estimates, the mass selection strategy should be efficient for the breeding of Japanese flounder.

利用限制性最大似然方法和贝叶斯方法分别估计大菱鲆养殖群体生长性状的遗传参数。利用39尾亲本进行人工授精育成28个后代家系，采集2462尾17月龄后代的收获体重。动物模型包括固定效应、协方差（孵化后110日龄的家系平均体重）、加性效应和残差。对于贝叶斯分析，根据后验条件分布的平均值和众数来估计遗传力和育种值。结果显示，对于加性效应，贝叶斯的后验均值（9320）是最高的，限制性最大似然方法的估计值（8088）次之，后验众数估计值最小（7849）。相应的三种遗传力估计值呈同样趋势。相应的三种育种值两两之间的皮尔逊相关系数均很高，最高的是后验均值和限制性最大似然方法的估计值（0.9969）。研究结果显示贝叶斯方法和限制性最大似然方法在遗传力和育种值估计方面差异小。本研究为大菱鲆的遗传参数估算提供另一种可行方法。

The aim of this study was to evaluate the genetic parameters of the growth performance of Takifugu rubripes. Heritabilities and genetic correlations were estimated for body weight (BW), body length (BL), total length (TL), chest measurement (CM) and trunk length (TKL) of T. rubripes from measurements of progeny at 6 months and 12 months. The results showed that the heritability was 0.37 for BW6, 0.19 for BL6, 0.35 for TL6, 0.29 for CM6, 0.26 for TKL6, 0.36 for BW12, 0.26 for BL12, 0.25 for TL12, 0.31 for CM12 and 0.15 for TKL12. The range of genetic correlations estimated at 6 months was 0.025–0.725 and −0.002–0.706 at 12 months. The results indicated that genetic improvement for faster growth rate or increased body weight in cultured T. rubripes was effective. Based on selection theory, the selection strategy for traits with medium heritability is flexible. Considering that these growth traits do not reach the high level of heritability, family selection should be expected. Given positive genetic correlations among BW, BL, TL, CM, and TKL at 6 months, the five traits could be improved simultaneously through selective breeding. As there was high genetic correlation only between BW12, BL12 and TL12, and negative correlations between TKL12 and BL12 as well as between CM12 and TL12, and only BW, BL and TL at 12 months could be improved simultaneously.

为了开展大菱鲆耐高温选育工作，对其进行耐高温性状及其相关生长性状的遗传评估是非常必要的。以来源于英国、法国、丹麦和挪威4个国家的不同群体构建大菱鲆选育家系，利用F₁的20个和F₂的22个耐高温选育家系进行耐高温实验，统计耐高温评估指标（UTT）和相应的实验鱼体重（每个家系选取40-50尾实验鱼）。基于Gibbs抽样的贝叶斯方法，采用包含母性效应和不包含母性效应的两种动物模型，对大菱鲆耐高温（UTT）和生长性状的遗传力以及这两个性状间的遗传相关和表型相关进行分析。结果表明，基于不包含母性效应的动物模型估计的体重和耐高温性状的遗传力以及这两个性状之间的表型相关和遗传相关分别为0.239±0.141,0.111±0.080,0.075±0.026和-0.019±0.011。基于包含母性效应的动物模型估计的这4个值分别为0.203±0.115,0.055±0.026,0.047±0.034和-0.024±0.028,体重和耐高温性状的母性效应分别为0.050±0.017和0.013±0.004。母性效应对这两个性状的遗传评估有一定的影响。本文的研究结论为制订合理的大菱鲆耐高温育种规划提供了理论依据。