孙女设计中标记密度对QTL定位精确性的影响

采用蒙特卡罗方法分析了在孙女设计中不同的嫩体结构、性状遗传力、ＱＴＬ效应大小和ＱＴＬ在染色体上的位置中个因素不同水平组合下４种标记密度（标记间隔５ｃＭ，１０ｃＭ，２０ｃＭ、５０ｃＭ对ＱＴＬ定位精确性（以均方误ＭＳＥ为衡量指标）的影响，并从经济学角度探讨了应用于标记辅助选（ＭＡＳ）的ＱＴＬ定位的最佳标记密度。结果表明，一般说来，在各因素水平都较低时，ＭＳＥ随标记密度加大而下降的相对幅度也较 小，反之

The Effect of Marker Density on QTL Mapping in a Granddaughter Design

Using Monte Carlo method, the effects of marker density on the accuracy of QTL mapping, measured with mean squared error (MSE) of QTL position estimates, were investigated for a granddaughter design under different population structures,heritabilities, sizes of QTL effect and QTL locations. The optimal marker densities for QTL mapping for applying to marker assisted selection, (MAS) were analyzed from an economic point of view. The results show that, in general, with the increase of marker density MSEs decrease much more rapidly when all other factors are at a high level than at a low level. When the sample size reaches a certain level (e.g. 40 families with 100 sons per family), or when the QTL effect is large (e.g. the QTL explains 50% of the genetic variance), the decrease of MSE will be only slightly affected by otrher factors. For the best benefits of MAS, the otihmal marker distances under different combinations of various factors were 5cM (small sample and large QTL, moderate sample, heritability and QTL, or large sample and small QTL), 10cM (moderate sample and high heritability or large QTL, or large sample and moderate heritability and QTL), and 20cM (large sample and high hetitability or large QTL).