Sperm Displacement in the Yellow Dung Fly, Scatophaga stercoraria: An Investigation of Male and Female Processes
Sperm Displacement in the Yellow Dung Fly, Scatophaga stercoraria: An Investigation of Male and Female Processes
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黄粪蝇、粪臭虫的精子置换：雄性和雌性过程的调查
DOI：
10.1086/303171
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
P. Stockley
中科院分区：
文献类型：
--
作者：
L. Simmons;G. Parker;P. Stockley
尽管对精子利用模式的研究已经无处不在，但昆虫受精的潜在机制还远远不清楚。一种被充分研究的系统是黄色粪蝇，在这种系统中，最后一只雄性的射精被认为会取代雌性精子库中的竞争对手的精子。在这里，我们使用标记了不同放射性同位素的雄性来跟踪交配的雄性射精通过雌性生殖道的运动。我们发现雄性射精进入交配囊，在交配过程中，雄性-1精子从受精囊移位。精囊中雄性-2射精量的增加与雄性-2受精获得的模式相匹配，表明受精时只利用精膜精子。此前，我们已经用精子置换的直接模型分析了这一系统，在该模型中，男性从受精囊中取代了竞争对手的精子。女性的数据和形态显然排除了这种机制。在这里，我们将这个模型与一个新的间接模型进行对比，在这个模型中，雌性通过将精子从法氏囊交配线交换到受精囊来促进精子的移位。这两个模型与观察到的精子利用模式相当吻合，因为精子转移到法氏囊交界处的速度大大超过了与受精囊的精子交换速度，因此第一个男性的精子在法氏囊中的浓度仍然显著低于第二个男性。这些分析为将雌性过程纳入昆虫精子利用模式的分析提供了一种定量的尝试。
Despite the ubiquity with which patterns of sperm utilization have been studied, the mechanisms underlying fertilization in insects are far from clear. One well‐studied system is the yellow dung fly, in which the last male's ejaculate is thought to displace rival sperm from the female's sperm stores. Here we follow the movement of the copulating male's ejaculate through the female's reproductive tract using males labeled with different radioisotopes. We find that males ejaculate into the bursa copulatrix and that male‐1 sperm are displaced from the spermathecae during copulation. The increase in male‐2 ejaculate in the spermathecae matches the pattern of male‐2 fertilization gain, indicating that only spermathecal sperm are utilized at fertilization. Previously we have analyzed this system with a direct model of sperm displacement in which the male displaces rival sperm from the spermathecae. The data, and morphology of the female, clearly preclude such a mechanism. Here we contrast this model with a new indirect model, in which the female facilitates displacement by exchange of sperm from the bursa copulatrix to the spermathecae. The two models give equivalent fits to the observed sperm utilization patterns because the rate of sperm transfer into the bursa copulatrix greatly exceeds the rate of sperm exchange with the spermathecae so that the concentration of the first male's sperm in the bursa remains considerably lower than that of the second male. These analyses provide a quantitative attempt to incorporate female processes into the analysis of sperm utilization patterns in insects.