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Polyandry is commonly maintained by direct benefits in gift-giving species, so females may remate as an adaptive foraging strategy. However, the assumption of a direct benefit fades in mating systems where male gift-giving behaviour has evolved from offering nutritive to worthless (non-nutritive) items. In the spider Paratrechalea ornata, 70% of gifts in nature are worthless. We therefore predicted female receptivity to be independent of hunger in this species. We exposed poorly-fed and well-fed females to multiple males offering nutritive gifts and well-fed females to males offering worthless gifts. Though the treatments strongly affected fecundity, females of all groups had similar number of matings. This confirms that female receptivity is independent of their nutritional state, i.e. polyandry does not prevail as a foraging strategy.ConclusionsIn the spider Pisaura mirabilis, in which the majority (62%) of gifts in nature are nutritive, female receptivity depends on hunger. We therefore propose that the dependence of female receptivity on hunger state may have evolved in species with predominantly nutritive gifts but is absent in species with predominantly worthless gifts. Fil: Pandulli Alonso, Irene. Laboratorio de Etología, Ecología y Evolución. Instituto de Investigaciones Biológicas Clemente Estable; Uruguay Fil: Quaglia, Agustín Ignacio Eugenio. Universidad Nacional de Cordoba. Facultad de Medicina. Instituto de Virologia "Dr. J.M. Vanella". Laboratorio de Arbovirus; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Albo, Maria J.. Laboratorio de Etología, Ecología y Evolución. Instituto de Investigaciones Biológicas Clemente Estable; Uruguay

Males from gift-giving species attempt to obtain food to offer to females. Therefore, food access may affect both their body condition and their reproductive success. In some species, males reduce the costs associated with giving gifts by reusing gifts, or by offering inedible items. Males from the spider Paratrechalea ornata (Trechaleidae) offer fresh prey or ‘genuine gifts’ to females, but also offer prey leftovers or ‘worthless gifts’. We examined gift weight and content, and their relation to male condition in the field. We also investigated how gift content, male condition and female reproductive status (virgin/mated) affect male mating success. In the field, most gifts were worthless; genuine gifts were heavier than worthless ones; and gift weights (both genuine and worthless gifts combined) were positively correlated with male condition. In the laboratory, males in good condition had higher mating success than males in poor condition. Males offering gifts (genuine or worthless) to virgin females enjoyed similar mating success and duration; neither differed significantly when compared to males without gift. In contrast, mated females behaved differently. Males without gifts were consistently rejected by mated females, while those that offered worthless gifts achieved matings. The interplay between male condition, prey access, female mating history and female preferences for gifts can favour the evolution of worthless gifts under certain conditions. Females do not penalize males with non-nutritive items by not mating or by reducing mating duration, but penalties may be potentially exerted via postcopulatory process.

In many species the function and evolution of nuptial gifts have been explained by the male mating effort hypothesis; i.e., males increase their fertilization success by donating gifts to females. The gift size may determine copulation duration and consequently affects male fertilization rate. In the well-known spider Pisaura mirabilis, previous studies suggested that the brightness of the gift (a prey wrapped in silk) affects female acceptance and larger gifts promote longer matings, but little is known from other gift-giving spider species. In this paper we test if gift size affects mating and remating success in the Neotropical and semi-aquatic spider Paratrechalea ornata (Trechaleidae). We exposed virgin females to males offering one fly (OF group) or four flies (FF group) wrapped in silk, and afterwards mated females were exposed to remating. Males from FF showed both longer courtship and mating than males from OF. We found a positive linear relationship between insertion duration of male intromitten...

In nuptial gift-giving species females sometimes select their potential mates based on the presence and size of the gift. But in some species, such as the Neotropical polyandrous spider Paratrechalea ornate male gifts vary in quality, from nutritive to worthless, and this male strategy can be in conflict with female nutritional benefits. In this species, males without gifts experience a reduction in mating success and duration, while males that offer worthless or genuine nutritive gifts mate with similar frequencies and durations. The female apparently controls the duration of copulation. Thus, there is scope for females to favour males offering gifts and further if these are nutritious, via post-copulatory processes. We first tested whether females differentially store sperm from males that offer the highest nutritional benefits by experimentally presenting females with males that offer either nutritive or worthless gifts (uninterrupted matings). Second, we carried out another set of experiments to examine whether females can select sperm based only on gift presence. This time we interrupted matings after the first pedipalp insertion, thus matching number of insertions and mating duration for males that: offered and did not offer gift. Our results showed that the amount of sperm stored is positive related to mating duration in all groups, except in matings with worthless gifts. Gift presence itself did not affect the sperm stored by females, while they store similar number of sperm in matings with males offering either nutritive or worthless gifts. We discuss whether females prefer males with gifts regardless, if content, because it represents an attractive and/or reliable signal. Or alternatively, they prefer nutritive nuptial gifts, as they are an important source of food supply and/or signal of male donor ability. Fil: Albo, María J.. Instituto de Invest. Biologicas "clemente Estable"; Uruguay Fil: Peretti, Alfredo Vicente. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentina