Data from: Multiple paternity in a wild population of Armadillidium vulgare: influence of infection with Wolbachia?

Female multiple mating has been extensively studied to understand how non-obvious benefits, generally thought to be of genetic nature, could overcome heavy costs such as an increased risk of infection during mating. However, the impact of infection itself on multiple mating has rarely been addressed. The interaction between the bacterium Wolbachia and its terrestrial crustacean host, Armadillidium vulgare, is a relevant model to investigate this question. In this association, Wolbachia is able to turn genetic males into functional females (i.e. feminization), thereby distorting the sex ratio and decreasing the number of available males at the population scale. Moreover, in A. vulgare, females have been shown to mate multiply under laboratory conditions and males prefer uninfected females over infected ones. Additionally, three different Wolbachia strains are known to infect A. vulgare and these strains differ in their transmission rate and virulence. All these elements suggest a potential impact of different Wolbachia strains on multiple mating. To investigate this assumption, we collected gravid females in a wild A. vulgare population consisting of both uninfected females and females infected with two different Wolbachia strains (wVulM and wVulC) and performed paternity analyses on the obtained broods using microsatellite markers. We demonstrate that (a) multiple paternity is common in this wild population of A. vulgare, with a mean number of fathers of 4.48 ± 1.24 per brood and (b) females infected with wVulC produced broods with a lower multiple paternity level compared to females infected with wVulM and uninfected ones. This work improves our knowledge of the impact of infections on reproductive strategies.

雌性多次交配已被广泛研究，旨在探明通常被认为具有遗传本质的隐性益处，如何能够克服交配过程中感染风险升高等高昂代价。然而，感染本身对多次交配的影响却鲜有探讨。细菌沃尔巴克氏体（Wolbachia）与其陆生甲壳类宿主普通卷甲虫（Armadillidium vulgare）之间的互作，是探究该问题的适宜模型。在这一互作体系中，沃尔巴克氏体可将遗传雄性转化为功能性雌性（即雌性化），从而扰乱种群性比，降低种群中可交配雄性的数量。此外，在普通卷甲虫中，已有研究表明雌性在实验室条件下会进行多次交配，且雄性更偏好未感染的雌性。同时，已知共有3种不同的沃尔巴克氏体菌株可感染普通卷甲虫，这些菌株在传播率与毒力方面存在差异。上述种种均提示，不同沃尔巴克氏体菌株可能对雌性多次交配产生影响。为验证这一假设，我们在同时包含未感染雌性与感染两种不同沃尔巴克氏体菌株（wVulM与wVulC）的普通卷甲虫野生种群中采集怀卵雌性，并利用微卫星标记（microsatellite marker）对获取的幼体群开展父系分析。结果表明：（a）多父本现象在该野生普通卷甲虫种群中十分普遍，每窝幼体的平均父本数量为4.48±1.24；（b）感染wVulC的雌性所产幼体群的多父本比例，低于感染wVulM的雌性与未感染雌性所产的幼体群。本研究增进了我们对感染如何影响生殖策略的认知。