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

Abstract

Female multiple mating has been extensively studied to understand how nonobvious 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, 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 harbouring both uninfected females and females infected with one of two different Wolbachia strains (wVulM and wVulC) and performed paternity analyses on the obtained broods using microsatellite markers. We demonstrate that (i) 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 (ii) females infected with wVulC produced broods with a lower multiple paternity level compared with females infected with wVulM and uninfected ones. This work improves our knowledge of the impact of infections on reproductive strategies.

Producing offspring in Armadillidium vulgare: Effects of genetic diversity and inbreeding

“…An evaluation of long-term fitness should now be performed, as short-term deleterious effects of inbreeding for one breeding event are not necessarily associated with a decrease in lifetime reproductive success (Van de Casteele, Galbusera, Schenck, & Matthysen, 2003). Lifetime reproductive success should also be estimated for heterozygous females under more natural settings: mating strategies such as mate choice or multiple mating (Valette, Durand, Bech, Grandjean, & Beltran-Bech, 2017) might allow females to avoid or compensate for developmental failure or mortality due to inbreeding, so higher fecundity might result in higher fertility.…”

Fine-scale population structure analysis in Armadillidium vulgare (Isopoda: Oniscidea) reveals strong female philopatry

“…Interestingly, this species displays both a monogamous mating system and biparental care (Linsenmair, 1984), as opposed to A. vulgare, which is characterized by a promiscuous mating system (Moreau & Rigaud, 2003;Valette et al, 2017) and nearly exclusive maternal care. It is then not surprising to observe different dispersal patterns across terrestrial isopods given the diversity in their ecology.…”

“…Females in several terrestrial isopod species have been shown to reproduce with several males (Johnson, 1982;Sassaman, 1978;Moreau et al, 2002) and males can mate with several females (Moreau and Rigaud, 2003). In particular, A. vulgare presents a promiscuous system, as females can produce broods with up to 7 fathers in the wild (Valette et al, 2017). Due to small size and regular moulting, genetic tools appear particularly relevant to study dispersal in this species.…”