Rochus Christina M, Johansson Anna M
Department of Animal Breeding and Genetics, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Box 7023, Uppsala, SE-75007 Sweden.
UFR Génétique, Élevage et Reproduction; Sciences de la Vie et Santé, AgroParisTech, Université Paris-Saclay, Paris, France.
Hereditas. 2017 Jan 30;154:4. doi: 10.1186/s41065-017-0026-4. eCollection 2017.
Breeds with small population size are in danger of an increased inbreeding rate and loss of genetic diversity, which puts them at risk for extinction. In Sweden there are a number of local breeds, native breeds which have adapted to specific areas in Sweden, for which efforts are being made to keep them pure and healthy over time. One example of such a breed is the Swedish Gute sheep. The objective of this study was to estimate inbreeding and genetic diversity of Swedish Gute sheep.
Three datasets were analysed: pedigree information of the whole population, pedigree information for 100 animals of the population, and microsatellite genotypes for 94 of the 100 animals. The average inbreeding coefficient for lambs born during a six year time period (2007-2012) did not increase during that time period. The inbreeding calculated from the entire pedigree (0.038) and for a sample of the population (0.018) was very low. Sheep were more heterozygous at the microsatellite markers than expected (average multilocus heterozygosity and Ritland inbreeding estimates 1.01845 and -0.03931) and five of seven microsatellite markers were not in Hardy Weinberg equilibrium due to heterozygosity excess. The total effective population size estimated from the pedigree information was 155.4 and the average harmonic mean effective population size estimated from microsatellites was 88.3. Pedigree and microsatellite genotype estimations of inbreeding were consistent with a breeding program with the purpose of reducing inbreeding.
Our results showed that current breeding programs of the Swedish Gute sheep are consistent with efforts of keeping this breed viable and these breeding programs are an example for other small local breeds in conserving breeds for the future.
种群规模较小的品种面临着近亲繁殖率上升和遗传多样性丧失的风险，这使其面临灭绝的危险。在瑞典，有许多当地品种，即适应瑞典特定地区的本土品种，人们一直在努力长期保持它们的纯正和健康。瑞典古特羊就是这样一个品种的例子。本研究的目的是估计瑞典古特羊的近亲繁殖和遗传多样性。
分析了三个数据集：整个种群的系谱信息、种群中100只动物的系谱信息以及100只动物中94只的微卫星基因型。在六年时间（2007 - 2012年）内出生的羔羊的平均近亲繁殖系数在该时间段内没有增加。根据整个系谱计算的近亲繁殖率（0.038）和从种群样本计算的近亲繁殖率（0.018）非常低。绵羊在微卫星标记处的杂合性高于预期（平均多位点杂合性和里特兰近亲繁殖估计值分别为1.01845和 -0.03931），并且七个微卫星标记中有五个由于杂合性过剩而不符合哈迪 - 温伯格平衡。根据系谱信息估计的总有效种群大小为155.4，根据微卫星估计的平均调和平均有效种群大小为88.3。系谱和微卫星基因型的近亲繁殖估计与旨在减少近亲繁殖的育种计划一致。
我们的结果表明，瑞典古特羊目前的育种计划与保持该品种生存能力的努力一致，这些育种计划是其他小型当地品种未来保护品种的一个范例。
