Multi-Male Mating and Female Choice Increase Offspring Growth in the Spider Neriene litigiosa (Linyphiidae)

Abstract

The purpose of this controlled-breeding study was to investigate the viability consequences of female choice and sequential polyandry for offspring in a way that would separate the influences of these two aspects of female sexual behaviour. Female sierra dome spiders, Neriene litigiosa (= Linyphia litigiosa) have many mating opportunities before their first oviposition. They typically mate two to three times before production of their first batch of eggs, although some females (ca. 16%) mate once. Strong fighters are preferred as first mates and principal sires of the offspring. Large males that give a vigourous performance during copulatory courtship are preferred as sires from among a female's secondary mates. In this study, the number of matings by free-living females was experimentally controlled and the size and copulatory vigour of all the females' mates were recorded. At the end of the breeding season, the females were collected and their broods were obtained in captivity. Randomly chosen subsets of 28 female's offspring were reared under standard conditions during the following spring. The spiderlings were reared for 27 days in the company of siblings under conditions that would encourage the expression of genetic variation in viability. Spiderling growth and survivorship were monitored. After controlling for maternal effects (i.e. female size and oviposition date) and variance in feeding opportunities among rearing groups, both mate number and mate size were positively and independently related to offspring growth rates and the size of offspring attained after emergence from the natal cocoon. The results support the hypotheses that the preference for large males yields viability benefits to offspring and that polyandry can augment the benefits of selective mating.