Hopkins Ben R, Sepil Irem, Wigby Stuart
Department of Zoology, University of Oxford, Oxford OX1 3SZ, UK.
Department of Evolution and Ecology, University of California - Davis, One Shields Ave., Davis, CA 95616, USA.
R Soc Open Sci. 2020 Mar 25;7(3):200130. doi: 10.1098/rsos.200130. eCollection 2020 Mar.
The ability of female insects to retain and use sperm for days, months, or even years after mating requires specialized storage organs in the reproductive tract. In most orders, these organs include a pair of sclerotized capsules known as spermathecae. Here, we report that some females exhibit previously uncharacterized structures within the distal portion of the muscular duct that links a spermatheca to the uterus. We find that these 'spermathecal duct presences' (SDPs) may form in either or both ducts and can extend from the duct into the sperm-storing capsule itself. We further find that the incidence of SDPs varies significantly between genotypes, but does not change significantly with the age or mating status of females, the latter indicating that SDPs are not composed of or stimulated by sperm or male seminal proteins. We show that SDPs affect neither the number of first male sperm held in a spermatheca nor the number of offspring produced after a single mating. However, we find evidence that SDPs are associated with a lack of second male sperm in the spermathecae after females remate. This raises the possibility that SDPs provide a mechanism for variation in sperm competition outcome among females.
雌性昆虫在交配后数天、数月甚至数年保留和利用精子的能力需要生殖道中有专门的储存器官。在大多数目昆虫中，这些器官包括一对被称为受精囊的硬化胶囊。在此，我们报告称，一些雌性昆虫在连接受精囊和子宫的肌肉管道远端呈现出以前未被描述的结构。我们发现这些“受精囊导管突出物”（SDPs）可能在一个或两个管道中形成，并且可以从管道延伸到精子储存胶囊本身。我们进一步发现，SDPs的发生率在不同基因型之间有显著差异，但不会随着雌性昆虫的年龄或交配状态而显著变化，后者表明SDPs不是由精子或雄性精液蛋白组成或刺激产生的。我们表明，SDPs既不影响受精囊中首次交配雄性的精子数量，也不影响单次交配后产生的后代数量。然而，我们发现有证据表明，雌性再次交配后，SDPs与受精囊中缺乏第二次交配雄性的精子有关。这增加了一种可能性，即SDPs为雌性之间精子竞争结果的差异提供了一种机制。
