Data from: The shield effect: nuptial gifts protect males against precopulatory sexual cannibalism

Several not mutually exclusive functions have been ascribed to nuptial gifts across different taxa. Although the idea that a nuptial prey gift may protect the male from pre-copulatory sexual cannibalism is attractive, it has previously been considered of no importance based on indirect evidence and rejected by experimental tests. We reinvestigated whether nuptial gifts may function as a shield against female attacks during mating encounters in the spider Pisaura mirabilis and whether female hunger influences the likelihood of cannibalistic attacks. The results showed that pre-copulatory sexual cannibalism was enhanced when males courted without a gift and this was independent of female hunger. We propose that the nuptial gift trait has evolved partly as a counteradaptation to female aggression in this spider species.在不同分类群中，求婚礼物（nuptial gifts）已被赋予多种并非互斥的功能。尽管“求婚猎物礼物可保护雄性免受交配前性食同类（pre-copulatory sexual cannibalism）侵害”这一假说颇具吸引力，但此前基于间接证据的研究认为其并无实际意义，且已被实验检验所否定。我们重新探究了两个问题：一是在蜘蛛华丽狡蛛（Pisaura mirabilis）的交配过程中，求婚礼物是否可作为抵御雌性攻击的屏障；二是雌性饥饿程度是否会影响性食同类攻击的发生概率。研究结果显示，当雄性无礼物求偶时，交配前性食同类的发生概率显著升高，且该现象与雌性的饥饿程度无关。我们提出，该蜘蛛物种的求婚礼物性状之所以演化，部分是作为对抗雌性攻击行为的反适应策略。