【作者】 张海滨；

【导师】 张国范；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋生物学， 2005， 博士

【摘要】 海湾扇贝自 1982 年引入我国以来,已成为我国北方海区重要的养殖贝类。其作为雌雄同体型生物,在自然情况下,既能自体受精,也能异体受精。一方面自交可增加纯合基因型的出现频率,从而增加隐性有害基因表现的机会,导致近交衰退;另一方面自交也可以作为品种纯化的有效手段,而在动植物育种中有着广泛的应用。本研究主要从这两方面入手,通过比较不同有效繁殖群体数对子代的影响,研究了作为雌雄同体型动物的海湾扇贝的近交生物学效应。同时,也利用其可自交的特点,选择优良个体进行连续自交培育了 F1、F2、F3代自交系;比较了自交系间的生长、存活等数量性状,并估计了配合力等参数。另外,通过不同遗传背景的养殖群体间的混交,建立了海湾扇贝的育种基础群体,并对其进行选择实验,估计了现实遗传力。还进行了海湾扇贝加拿大群体和墨西哥湾扇贝的杂交实验,分析了 F1的杂种优势及母体效应。主要结果如下:1. 采用不同有效繁殖群体数的海湾扇贝进行繁殖,研究了近交对海湾扇贝 F1、F2 的生长、存活等生物学特性的影响。实验共设置了 6 个梯度,分别采用 1、2、10、30、50 个亲贝进行繁殖,并以常规生产为对照组。在子一代,实验各组第 1 天的 D 形幼虫壳长并没有显著差别(P>0.05)。随着幼虫的不断生长,差别越来越明显,表现为自交组的生长和存活均低于其他各组, 而 Ne=2、10、30、50 及对照组间的差异并不显著(P>0.05)。养成期间,自交组个体壳长、壳高、壳宽及总重的生长,均明显低于其他各组。另外,越冬期间,自交组的存活率,也明显低于其他各组。在子二代,近交衰退不仅存在于 Ne=1 组,而且也存在于 Ne=2 组。这两组的生长和存活都明显低于其他各组(Ne=10, 30, 50, control),而后者之间没有显著区别。同时,Ne=1 组的近交衰退明显高于 Ne=2 组。由此可见,低的有效繁殖群体数(Ne),增加了近交的可能性,能够对子代产生一些不利的影响。因此,在苗种生产中维持较高的 Ne 水平是非常有必要的。而且,由于海湾扇贝较高的产生配子的能力(单个亲贝就能够产生大量的配子),也可能导致近交水平的增加,因此推荐从不同的养成地点选择亲贝进行苗种培育。 i<WP=7>张海滨 海湾扇贝近交生物学效应和遗传改良研究 博士学位论文 2. 采用两个海湾扇贝的群体进行混合交配,建立了基础群体。经过一年的养殖,以壳长为指标对所建立的基础群体进行选择,从 1300 个体中选择壳长最大的 10%个体(选择强度为 1.755)进行繁殖,并随机从基础群体中选择相同数量的个体作为对照。结果显示,在幼虫阶段选择组的生长和存活明显高于对照组(P<0.01), 现实遗传力为 0.52±0.24。由于在稚贝期间,对照组的养殖密度相对较低,在养成阶段开始时(第 100 天),对照组的平均壳长大于选择组。随着密度调整一致后,在养成阶段(第 100 天至 160 天)的生长速度显著大于对照组。同时,选择组在这一阶段的存活率也明显高于对照组。实验说明,利用不同遗传背景的海湾扇贝,建立遗传多样性高的基础群体,并在此基础上进行选择育种,是一种较有潜力的海湾扇贝种质改良的方法。 3. 进行了海湾扇贝加拿大群体和墨西哥湾群体的杂交实验,对杂种一代及对照群体的生长和存活进行了比较。四个子代群体的第一天的 D 形幼虫的壳长没有显著区别(94.27μm,93.78μm, 93.48μm, 93.58μm)。在第 10 天,两个杂交组(CM, MC)的壳长(155.35μm,156.14μm)显著大于两个对照群体(141.97μm, 146.20μm),且 MC 的生长速度大于 CM。同时,存活率的杂种优势明显大于生长的杂种优势。在幼虫阶段,卵源和交配方式对壳长和存活都具有显著的影响。杂种优势不仅存在于幼虫阶段,而且在稚贝及成体阶段一直存在。在第 170 天,CM 的个体明显大于其它三个组合,虽然 MC 的壳长和壳高也大于两个对照群体(MM,CC),但差异不显著。 4.从海湾扇贝群体中选择优良个体,建立了 F1、F2、F3 自交系,并研究各家系在幼虫及养成阶段的生物学特征。实验结果表明,在不同的家系间存在着明显的遗传变异,因而进行家系的选择和培育有着广泛的应用前景。经过三代的自交选育,已经得到一些生长速度快且存活率高的家系。 5. 本研究中利用起源于F2自交系的三个杂交家系为材料,进行了3×3双列杂交,分析各杂交组合的杂种优势,同时计算了各家系间的一般配合力和特殊配合力,为海湾扇贝杂种优势的利用提供一定的理论依据。结果表明,31×40杂种优势最为明显,而且随着幼虫的生长,杂种优势值呈增加趋势。杂种优势,一般配合力和特殊配合力存在一定的相关性,一般配合力高的组合,特殊配合力也高,杂种优势也明显。更多还原

【Abstract】 The Bay scallop, Argopecten irradians (Lamarck), has served as a primary cultured speciesin north China since it was introduced from the United States in 1982 (Zhang FS et al., 1986).This species is a functional hermaphrodite. It can self-fertilize and cross-fertilize in nature.Self-fertilization can result in inbreeding depression by increasing the frequency of recessiveharmful gene. At the same time, self-fertilization can be seen as a useful tool to produce purelines and broadly used in breeding program. In this study, inbreeding effects was evaluated by comparing growth and survival of F1, F2with different effective population size. F1, F2, F3 families were obtained by self-fertilizing. Thegrowth and survival of families was observed, and combining ability were estimated. A basepopulation was produced by cross of two cultured populations of bay scallop, and the realizedheritability was estimated. A complete diallel cross between two bay scallop population,Argopecten irradians concentricus Say (M) and Argopecten irradians irradians Lamarck (C),was carried out, and heterosis and maternal effect were discussion. The main results of this study are listed as follows: 1. The experiment was designed to study the effect of effective population size (Ne) on thegrowth and survival of F1 and F2 bay scallop Argopecten irradians. To determine the magnitudeof these effects, six experimental groups were produced: Ne=1, 2, 10, 30, 50, control. At the firstgeneration, the shell length of Larvae for all experimental groups was not different from eachother at of 1th day D-larva. With the growth of the larvae, the growth and survival of Ne =1 groupwere gradually smaller than that of the others, while there was no significant difference amongNe=2, 10, 30, 50 and control groups. During grow-out stage, the growth of shell length, shell iii<WP=9>张海滨 海湾扇贝近交生物学效应和遗传改良研究 博士学位论文height, shell width and wet weight for Ne =1 group was lower than the others too. In winter,survival rate of Ne=1 is lower than that of others (P <0.05). At second generation, inbreedingdepression exists not only in Ne=1 group but also in Ne=2 group. The growth and survival ratesof the two groups are significantly lower than those of the other groups (Ne=10, 30, 50, control).There is no significant difference between the later (P>0.05). At the same time, the amount ofdepression in Ne=1 group is significantly higher than that of Ne=2 group (P<0.05). These resultsindicate that the low effective population size (Ne), which increases the possibility of inbreeding,can lead to some harmful effects to the offspring. So it is essential to maintain a high level of Nein commercial seed production. Furthermore, as the high fecundity of bay scallop might lead toincreased inbreeding, selecting broodstock from different growout sites is recommended. 2. A base population was produced by cross of two cultured populations of bay scallopArgopecten irradians irradians Lamarck. After 1 year rearing, truncation selection of the top10% (i=1.755) was carried out in the base population of about 1300 adults. A control parentalgroup with identical number to the select parental group was randomly selected from the entirepopulation before isolation of the select parental group. The result showed that, at larval stage,the growth rate of larvae in the selected line was significantly higher than that of control(P<0.05), and that the realized heritability was estimated to be 0.52±0.24. Due to the lowerdensity of control at spat stage, mean shell length of control line was larger than that of selectline at day 110. With the density was adjusted to the same between two lines in grow out stage(from day 110-160), daily growth rate of selected line was significantly higher than that ofcontrol line (P<0.05). Survival of se更多还原