近交对大菱鲆体尺性状生长的遗传影响

为研究近交对大菱鲆体尺生长的动态影响,构建了非近交和2个不同近交水平的30个家系。在生长期内,定期测量了1 082尾个体的全长、体长、头长、体宽和尾柄高等体尺性状。选择三阶勒让德(Legendre)多项式为子模型,采用随机回归模型估计了这些体尺性状的遗传参数。考虑近交和不考虑近交作为固定效应的随机回归分析表明:近交显著地提高了所有体尺性状遗传力估计值。与远交组相比,近交导致了体尺性状不同程度的衰退,但衰退程度在2个近交组间没有表现出明显差异。5个体尺性状之中,全长和体长表现出较为相似的近交衰退趋势,而体宽、头长和尾柄高表现出较为一致的趋势。与非近交组相比,全长和体长在350日龄前,近交系数0.25的个体体长性状并未出现近交衰退,反而有所提高,而近交系数为0.375的组,这2个性状表现出衰退。全长和体长的近交衰退随着年龄的增长而加重。0.25和0.375两种近交水平的群体在第400和第650生长日之间对体长的生长曲线几乎没有影响。在整个测量周期内,近交水平对尾柄高的生长曲线的影响几乎没有差异。而在第650生长日龄后,全长、体长和头长的近交衰退随着近交程度增加而加快。这些近交分析的结果可以用来指导大菱鲆配套系选育过程中亲本群体遗传纯化过程中的近交控制。

Genetic effects of inbreeding on traits of morphological traits in Turbot (Scophthalmus maximus L.)

Thirty families with two different levels of inbreeding and out-crossing were produced to investigate the dynamic effect of inbreeding on morphological traits growth in turbot.A total of 1 082 fish were measured periodically for total length (TL),body length (BL),head length (HL),body width (BW),and caudal peduncle height (CPH) during the growth period.The Legendre polynomials of three orders were selected to optimally fit growth trajectory.Regarding them as the submodel,we introduced a random regression model for estimating genetic parameters of these traits.Random regression analyses if inbreeding degree was considered as a fixed effect showed that inbreeding significantly enhanced the heritability estimates for all morphological traits.Compared to out-crossing group,the inbreeding leads morphological traits to depression in different degrees,while the degree of depression was closer to each other at 0.25 and 0.375 inbreeding coefficients,not depended on the inbreeding degree.Among the five morphological traits,the TL and BL showed similar tendency of inbreeding depression,while others exhibited consistent tendency.Compared to the out-crossing group,with 0.25 inbreeding coefficients,promotion instead of depression was observed on TL and BL during 350 growth days,while,depression was detected with 0.375 inbreeding coefficient.The depression for TL and BL aggravated with the growth ages.The growth trajectories of BL trait were not affected at all in both groups with the inbreeding coefficients of 0.25 and 0.375 during 400 and 650 growth days.During the whole period of measurement,almost no changes were seen in the influences on growth trajectories of CPH with different inbreeding degrees.However,the inbreeding depression of TL,BL and HL accelerated with the increasing inbreeding degree after 650 growth days.This study would be used to guide the inbreeding control for parental genetic purification in Turbot breeding system.