Inbreeding depresses sperm competitiveness, but not fertilization or mating success in male Tribolium castaneum
Inbreeding depresses sperm competitiveness, but not fertilization or mating success in male Tribolium castaneum
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DOI：
10.1098/rspb.2010.0514
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发表时间：
2010-11-22
影响因子：
4.7
通讯作者：
Gage, Matthew J. G.
中科院分区：
文献类型：
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作者：
Michalczyk, Lukasz;Martin, Oliver Y.;Gage, Matthew J. G.
随着种群下降到近亲繁殖的可能性增加，随后纯合隐性有害表达的增加和/或杂合子优势的丧失可能导致近交衰退。在这里，我们测量如何在复制线的面粉甲虫赤拟谷盗近亲繁殖影响男性生殖健康的存在或不存在的男性-男性竞争。交配模式对雄性进化的影响被强制一夫一妻制的交配方式所消除。经过八代的近亲繁殖，我们发现在没有竞争的情况下，雄性的生育能力不受影响。然而，我们发现显着的近亲繁殖抑制精子竞争力：非近亲繁殖的男性赢得了57%的受精竞争，而近亲繁殖的等价物只有42%.We还发现，在精子竞争中的P-2“进攻”的作用是显着更压抑的近亲繁殖下比精子“防御”（P-1）。交配行为并不能解释这些差异，也没有近亲繁殖或非近亲繁殖的男性后代的生存能力的差异。精子长度的变化是显着更大的近交系男性的射精。我们的研究结果表明，男性实现正常受精成功的能力并没有压抑强烈的近亲繁殖，但近亲繁殖抑郁症发生在这些特征时，精子竞争的条件下产生。
As populations decline to levels where reproduction among close genetic relatives becomes more probable, subsequent increases in homozygous recessive deleterious expression and/or loss of heterozygote advantage can lead to inbreeding depression. Here, we measure how inbreeding across replicate lines of the flour beetle Tribolium castaneum impacts on male reproductive fitness in the absence or presence of male-male competition. Effects on male evolution from mating pattern were removed by enforcing monogamous mating throughout. After inbreeding across eight generations, we found that male fertility in the absence of competition was unaffected. However, we found significant inbreeding depression of sperm competitiveness: non-inbred males won 57 per cent of fertilizations in competition, while inbred equivalents only sired 42 per cent. We also found that the P-2 'offence' role in sperm competition was significantly more depressed under inbreeding than sperm 'defence' (P-1). Mating behaviour did not explain these differences, and there was no difference in the viability of offspring sired by inbred or non-inbred males. Sperm length variation was significantly greater in the ejaculates of inbred males. Our results show that male ability to achieve normal fertilization success was not depressed under strong inbreeding, but that inbreeding depression in these traits occurred when conditions of sperm competition were generated.