Department of Animal Science, North Carolina State University, Box 7621, 27695, Raleigh, NC, USA.
Theor Appl Genet. 1992 Jul;84(3-4):307-12. doi: 10.1007/BF00229488.
Correlated responses were studied in lines of mice selected for eight generations based on the criterion of a restricted selection index. Two replicate lines were selected in each treatment as follows: HE, high epididymal fat pad weight (EF) with zero change in body weight (BW) at 12 weeks of age; LE; low EF with zero change in BW; and RS, randomly. Correlated responses showed considerable variation between replicates, suggesting that genetic drift was important. Further, correlated responses for most traits were relatively small, probably because of low selection intensity. The HE line responded as expected in component traits of the restricted index. Associated compositional traits in HE responded as predicted since traits correlated with adiposity increased and hind carcass weight did not change significantly. Feed intake increased and feed efficiency (weight gain/feed intake) decreased in HE, as predicted. In contrast, the LE line did not respond in component traits as predicted since EF did not decrease and BW increased. Consequently, LE exhibited little change in traits associated with adiposity, but hind carcass weight, feed intake and feed efficiency increased. Of the correlated responses scored for fitness traits (littering rate, number of days from pairing of mate to littering, litter size and preweaning pup survival rate), significant effects were found for decreased littering rate in LE and increased prenatal survival rate in HE. In summary, correlated responses to restricted index selection generally agreed with expectation when responses in component traits of the index were considered.
选择指数受限的情况下，经过八代的选育，研究了相关的响应。在每个处理中，都选择了两个重复线，如下所示：HE，附睾脂肪垫重量高（EF），12 周龄体重（BW）不变；LE，EF 低，BW 不变；RS，随机。相关性响应在重复之间变化很大，这表明遗传漂变很重要。此外，大多数性状的相关响应相对较小，可能是由于选择强度低。HE 线在受限指数的组成性状中表现出预期的反应。与肥胖相关的性状呈预测的反应，因为与肥胖相关的性状增加，后躯体重没有显著变化。HE 组的采食量增加，饲料效率（体重增加/饲料摄入量）降低，这是预期的结果。相反，LE 线在预期的组成性状中没有反应，因为 EF 没有减少，BW 增加。因此，LE 组与肥胖相关的性状变化不大，但后躯体重、采食量和饲料效率增加。对与适应性相关的性状（产仔率、配对到产仔的天数、产仔数和断奶前幼仔存活率）进行的相关响应评分，发现 LE 组的产仔率降低和 HE 组的产前存活率增加具有显著影响。总之，当考虑到指数的组成性状的反应时，对受限指数选择的相关反应通常与预期一致。
