Hosken DJ, Ward PI
Zoologisches Museum, Universität Zürich-Irchel, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
J Insect Physiol. 2000 Oct 1;46(10):1355-1363. doi: 10.1016/s0022-1910(00)00057-3.
While sperm competition has been extensively studied, the mechanisms involved are typically not well understood. Nevertheless, awareness of sperm competition mechanisms is currently recognised as being of fundamental importance for an understanding of many behavioural strategies. In the yellow dung fly, a model system for studies of sperm competition, second male sperm precedence appears to result from a combination of sperm displacement and sperm mixing. Displacement was until recently thought to be directly from the female's sperm stores, the spermathecae (i.e. males were thought to ejaculate directly into these stores), and under male control. However, recent work indicates displacement is indirect (i.e. males do not ejaculate directly into the sperm stores) and that it is female-aided, although the evidence was not based on direct observation. Here, we used histological techniques to directly determine interactions during copula and sperm transfer. Our results are consistent with inference and clearly show that males ejaculate into the bursa copulatrix. Our data are also consistent with active female involvement in sperm displacement, which is indirect, and indicate the aedeagus may remove some spermatozoa from the bursa at the end of copula. In addition, evidence suggests females aid sperm transport to and from the spermathecae, possibly by muscular movement of a spermathecal invagination.
虽然精子竞争已得到广泛研究，但其中涉及的机制通常仍未得到充分理解。然而，目前人们认识到，了解精子竞争机制对于理解许多行为策略至关重要。在黄粪蝇（一种用于精子竞争研究的模型系统）中，第二只雄蝇的精子优先地位似乎源于精子置换和精子混合的共同作用。直到最近，置换一直被认为是直接从雌性的精子储存器官——受精囊中进行的（即雄性被认为直接将精液射入这些储存器官），并且受雄性控制。然而，最近的研究表明，置换是间接的（即雄性不会直接将精液射入精子储存器官），而且是在雌性协助下进行的，尽管证据并非基于直接观察。在这里，我们使用组织学技术直接确定交配和精子转移过程中的相互作用。我们的结果与推断一致，清楚地表明雄性将精液射入交配囊。我们的数据还与雌性积极参与间接的精子置换一致，并表明阴茎可能在交配结束时从交配囊中清除一些精子。此外，有证据表明雌性协助精子往返于受精囊，可能是通过受精囊内陷的肌肉运动来实现的。
