Sperm blocking is not a male adaptation to sperm competition in a parasitoid wasp

The extent to which sperm or ejaculate-derived products from different males interact during sperm competition – from kamikaze sperm to sperm incapacitation – remains controversial. Repeated matings in the parasitoid wasp Nasonia vitripennis lead to a short-term reduction of efficient sperm use by females, which is crucial for a haplodiploid organism when needing to allocate sex adaptively (i.e. by fertilizing eggs to produce daughters). Repeated matings by females in this species therefore constrain sex allocation through this “sperm-blocking” effect, eliciting a cost to polyandry. Here we explore the causes and consequences of sperm-blocking, and test the hypothesis that it is an ejaculate-related trait associated with sperm competition. First, we show that sperm blocking, which leads to an over-production of sons, is not correlated with success in either offensive or defensive roles in sperm competition. Then, we show that the extent of sperm blocking is not affected by self-self or ...不同雄性的精子或射精衍生产物在精子竞争（sperm competition）过程中的相互作用程度——从自杀式精子（kamikaze sperm）到精子失能（sperm incapacitation）——这一问题迄今仍存在争议。在寄生蜂（parasitoid wasp）丽蝇蛹集金小蜂（Nasonia vitripennis）中，雌性多次交配会导致其短期内高效利用精子的能力下降，而这对于需要进行适应性性别分配的单倍二倍体生物（haplodiploid organism）而言至关重要，即通过受精卵子产生雌性后代。因此，该物种雌性的多次交配会通过这种“精子阻断（sperm-blocking）”效应限制性别分配，进而引发一妻多夫制（polyandry）的演化代价。本研究旨在探讨精子阻断效应的成因与后果，并验证其为与精子竞争相关的射精相关性状这一假说。首先，我们证实，导致雄性后代过量产生的精子阻断效应，与精子竞争中的进攻性或防御性角色的成功均无相关性。其次，我们证实精子阻断的程度不受自体-自体（self-self）或……的影响。