家畜近亲繁殖群体连锁不平衡的分析

AN ANALYSIS OF LINKAGE DISEQUILIBRIUM IN INBRED POPULATIONS OF DOMESTIC ANIMALS

本文分析了家畜近亲繁殖群体连锁位点基因遗传平衡的实现，推导出了配子型频率及基因型频率通用递推公式．研究证明，近交群体不同于随机交配大群体，其连锁不平衡值d（绝对值）随世代的下降速率不仅取决于重组率，而且也依赖于近交速率．近交越剧烈，则d下降越慢；达平衡态时，近交群体d值并不一定等于0．连锁越紧密，近交越剧烈，则平衡d值越大．最后讨论了研究结果在家畜育种中的应用．

The approach to genetic equilibrium for 2 linked loci in animal populations under inbreeding systems was analyzed，and the recurrent equations for gamete frequencies and genotype frequencies of inbred populations in different generations were derived by the present study.Results showed that,the amount of linkage disequilibrium（D）was progressively reduced with each succeeding generation，and the rate of reduction depandent not only on recombination frequency（c），as was the case in infinite random mating populations，but also on inbreeding rate（△F）．The higher the △F and the lower the c,the slower the rate of decrease of D．When equilibrium wsa reached，the value of D in inbred populations was not certainly zero．The absolute value of D at eqilibrium was bigger with smaller c and higher △F．At last the practical consequences and implications of the present study to animal breeding were discussed．