罗氏沼虾开放和闭锁核心育种群生长和存活性能分析

开放核心育种体系可增加核心群体的选择强度,进而增加育种目标性状的遗传进展。本研究以罗氏沼虾(Macrobrachium rosenbergii)为研究对象,向闭锁核心群(closed nucleus population,NP)内引入扩繁群(multiplier population, MP)个体,构建两个杂交群体(正交群体NP/MP,反交群体MP/NP),并以闭锁核心群(NP/NP)为对照,应用线性混合效应模型(linear mixed effects model, LME)和广义线性混合模型(generalized linear mixed model, GLMM)对不同群体收获体重和存活率的估计边际均值进行比较,评估在虾类选择育种中构建开放核心育种体系的可行性。结果显示:(1) NP/NP、MP/NP和NP/MP群体的收获体重估计边际均值分别为45.83 g、49.57 g和46.62 g;与NP/NP群体相比, MP/NP和NP/MP群体分别提高了8.16%和1.72%。(2) NP/NP、MP/NP和NP/MP群体的存活率估计边际均值分别为72.92%、68.04%和66.55%;与NP/NP群体相比,MP/NP和NP/MP群体分别降低了6.69%和8.74%。综上所述,在罗氏沼虾核心群中引入扩繁群个体,构建开放核心育种群体,可以有效地增加收获体重的遗传进展;同时在制定选择指数时,应加大存活性状的权重,选择生长和存活性能均优良的家系生产扩繁群体,导入闭锁核心育种群,构建生长和存活性能均优良的开放核心育种群。

Growth and survival analysis of open and closed nucleus breeding populations in Macrobrachium rosenbergii

Macrobrachium rosenbergii is the main cultured freshwater shrimp in China and has brought substantial economic benefits. However, the accumulation of inbreeding due to uncontrolled mating within the introduced population over many generations has caused a serious depression in the genetic resources of M. rosenbergii; therefore, there is an urgent need to select effective strategies to improve the genetic gain. Many studies have reported that the open nucleus breeding system can greatly improve the genetic progress of objective traits during the breeding process of cattle and sheep; thus, this study aimed to explore the possibility of constructing an open nucleus breeding population of shrimps. In the selection process of M. rosenbergii, the multiplier population (MP) was introduced into the closed nucleus population (NP), and two hybrid populations between NP and MP populations (the cross population denoted by NP/MP, the reciprocal population denoted by MP/NP) were constructed. The NP population was used as the control, and estimated marginal means for the harvest weight and survival rate for different populations were compared using a linear mixed-effects model (LME) and generalized linear mixed model (GLMM). The results showed that:(1) the estimated marginal means of harvest body weight for the NP/NP, MP/NP, and NP/MP populations were 45.83 g, 49.57 g, and 46.62 g, respectively. Compared with the NP/NP population, the MP/NP and NP/MP populations increased by 8.16% and 1.72%, respectively. (2) The estimated marginal means of survival rates for the NP/NP, MP/NP, and NP/MP populations were 72.92%, 68.04%, and 66.55%, respectively. Compared with the NP/NP population, the MP/NP and NP/MP populations decreased by 6.69% and 8.74%, respectively. In conclusion, the genetic gain of harvest weight can be effectively increased by introducing foreign individuals to the NP population and constructing an open nucleus breeding system for the selective breeding of shrimp. Furthermore, the weight of survival traits should be increased when the selection index is formulated. The family presenting excellent growth and survival performance should be selected to produce the MP population, introduce the NP population, and construct the open nucleus breeding population.