Reduced genetic load revealed by slow inbreeding in Drosophila melanogaster.
Reduced genetic load revealed by slow inbreeding in Drosophila melanogaster.
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DOI：
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发表时间：
1995
期刊：
影响因子：
3.3
通讯作者：
B. Latter;J. Mulley;D. Reid;L. Pascoe
中科院分区：
文献类型：
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作者：
B. Latter;J. Mulley;D. Reid;L. Pascoe
在竞争性和非竞争性条件下，研究了以每代约1%的初始速率近交的黑腹果蝇种群的生殖适合度下降速率。育种群体大小在近交系中是可变的，估计调和平均值为66.7 +/- 2.2。60行保持没有储备，75%的生存期210代的缓慢近亲繁殖，然后迅速近交全同胞交配近纯合性。近亲繁殖的初始速率估计为每代0.96 +/- 0.16%，对应于约50的有效群体大小。然而，随着时间的推移，近亲繁殖率显着下降，平均每代只有0.52 +/- 0.08%，在210代期间，最有可能是由于在小种群的遗传抽样和选择建立了关联超显性。在非拥挤条件下，竞争力和适合度的近交衰退率分别为87 +/-3%和27 +/-5%，近交系数每增加1%，相应的衰退率分别为2.0 +/-0.3和0.32 +/-0.07%。致死的第二染色体在所得到的近纯合系的频率是5%的顺序，致死的自由第二染色体显示出平均活力在拥挤和不拥挤的条件下约95%，和他们的人口笼健身是60%的Cy/+杂合子。可以得出结论，纯合基因型的有害基因的主要影响已被淘汰，在缓慢的近亲繁殖可能会显示远低于抑郁症的生殖适合度比早期研究野生染色体纯合子。在竞争条件下，由于整个基因组的纯合性而导致的适合度损失可能小至85-90%，在最佳环境中为25-30%。
The rate of decline in reproductive fitness in populations of Drosophila melanogaster inbred at an initial rate of approximately 1% per generation has been investigated under both competitive and noncompetitive conditions. Breeding population size was variable in the inbred lines with an estimated harmonic mean of 66.7 +/- 2.2. Of the 60 lines maintained without reserves, 75% survived a period of 210 generations of slow inbreeding and were then rapidly inbred by full-sib mating to near-homozygosity. The initial rate of inbreeding was estimated to be 0.96 +/- 0.16% per generation, corresponding to an effective population size of approximately 50. However, the rate of inbreeding declined significantly with time to average only 0.52 +/- 0.08% per generation over the 210 generation period, most likely due to associative overdominance built up by genetic sampling and selection in the small populations. The total inbreeding depression in fitness was estimated to be 87 +/- 3% for competitive ability and 27 +/- 5% for fitness under uncrowded conditions, corresponding to rates of decline of 2.0 +/- 0.3 and 0.32 +/- 0.07%, respectively, per 1% increase in the inbreeding coefficient. The frequency of lethal second chromosomes in the resultant near-homozygous lines was of the order of 5%, lethal free second chromosomes showed a mean viability under both crowded and uncrowded conditions of approximately 95%, and their population cage fitness was 60% that of Cy/+ heterozygotes. It can be concluded that homozygous genotypes from which deleterious genes of major effect have been eliminated during slow inbreeding may show far less depression in reproductive fitness than suggested by earlier studies of wild chromosome homozygotes. The loss in fitness due to homozygosity throughout the entire genome may be as little as 85-90% under competitive conditions, and 25-30% in an optimal environment.