Hohenboken W D, Wagner C R, Blodgett D J
Animal and Poultry Sciences Department, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.
Theriogenology. 1998 May;49(7):1397-407. doi: 10.1016/S0093-691X(98)00086-7.
This study was conducted to determine whether inbreeding coefficients of selected parents or of progeny differed between lines of mice selected for increased or decreased responsiveness to a nutritional toxicosis. A second objective was to determine whether the influence of inbreeding of parents and/or progeny on reproductive traits differed between those lines. Mice were selected divergently for 8 generations for the effect on post-weaning growth of endophyte-infected fescue seed in their diet. Forty pairs (or in Generation 7, 20 pairs) were selected and mated per generation in each line. Inbreeding increased 0.5 to 0.6% per generation in both lines, a rate close to that predicted from genetic theory. Inbreeding coefficients of selected parents were not higher in the susceptible than in the resistant line. A difference would have been expected if the inbreeding coefficient had been correlated with susceptibility to toxicosis. The magnitudes of inbreeding depression for reproductive traits did not differ significantly between lines. The average inbreeding coefficient of the potential litter tended to be higher in nonfertile than fertile matings (P = 0.10), but inbreeding coefficients of sires and dams did not differ between successful and unsuccessful matings. Inbred litters tended to be born earlier than noninbred litters (P = 0.10). Inbred dams produced smaller litters than noninbred dams (main effect P < 0.05) but only when the litter also was inbred (interaction P < 0.01). Sex ratio was not influenced by inbreeding of sire, dam or litter, but there was a higher proportion of male progeny in the susceptible than in the resistant line (P = 0.01). To avoid reduced reproductive fitness, laboratory animal populations should be managed to minimize inbreeding of progeny and dam.
本研究旨在确定，在针对营养性中毒反应性增强或减弱而选育的小鼠品系中，所选亲本或子代的近亲繁殖系数是否存在差异。第二个目标是确定亲本和/或子代近亲繁殖对繁殖性状的影响在这些品系之间是否不同。根据内生真菌感染的羊茅种子对断奶后生长的影响，对小鼠进行了8代的反向选择。每一代在每个品系中选择40对（或在第7代时选择20对）进行交配。两个品系的近亲繁殖率均以每代0.5%至0.6%的速度增加，这一速度接近遗传理论预测值。所选亲本的近亲繁殖系数在易感品系中并不高于抗性品系。如果近亲繁殖系数与中毒易感性相关，那么本应出现差异。两个品系之间繁殖性状的近亲繁殖衰退幅度没有显著差异。不育交配中潜在窝仔的平均近亲繁殖系数往往高于可育交配（P = 0.10），但成功交配和未成功交配的公鼠和母鼠的近亲繁殖系数没有差异。近亲繁殖的窝仔往往比非近亲繁殖的窝仔出生更早（P = 0.10）。近亲繁殖的母鼠产仔数比非近亲繁殖的母鼠少（主效应P < 0.05），但只有当窝仔也是近亲繁殖时才会出现这种情况（交互作用P < 0.01）。性别比例不受父本、母本或窝仔近亲繁殖的影响，但易感品系中雄性后代的比例高于抗性品系（P = 0.01）。为避免繁殖适应性下降，应管理实验动物种群，尽量减少子代和母本的近亲繁殖。
