CONICET | Buscador de Institutos y Recursos Humanos

One remarkable reproductive feature in animals with internal fertilization is a reduction in sperm viability overtime in females. Whether this reduction is driven by male?male competition and/or cryptic female choice is unclear.From the perspective of cryptic female choice, we postulated that sperm viability is affected by a particular malecopulatory behaviour. In this study, we investigated the following aspects: (1) sperm viability in mated femalesvs. males; (2) whether sperm viability varies temporally after mating; and (3) whether male copulatory behaviourcovaries positively with sperm viability within females. We used the spider Holocnemus pluchei, whose males useseveral copulatory behaviours to court females. We found that females that stored sperm for 4 or 15 days showedno difference in sperm viability but had lower sperm viability compared with males, and males that performed alonger post-insemination behaviour had higher sperm viability inside the female. It is unclear how sperm viability isreduced and how male post-insemination behaviour affects this. It is possible that extending copulation allows malesto induce females to keep sperm alive for longer. This result is predicted by theory whereby males induce females tofacilitate sperm to reach and fertilize eggs based on male postcopulatory behaviour.