Pavón-Peláez et al., RawData Animal Behaviour 200121

We examined individual male differences in mating tactics in a gift-giving spider (Pratrechalea ornata) by repeatedly exposing males to sexually mature females in the presence or absence of live prey. If the observed variation in mating tactics is determined by an intrinsic gift-giving strategy at the level of the individual, this would result in discrete responses where each male would express only one phenotype regardless of prey availability. This could happen if there is significant variation in the ability of males to acquire the resources necessary to produce gifts. Under this scenario, we expect males to show high levels of repeatability in their tactic regardless of the presence of prey items. Alternatively, a male’s gifts may reflect prey availability. When a nutrient rich prey item is present, a gift-giving male should offer this to a female; however, when such a prey item is absent, a male can maximise the probability of a mating by wrapping inedible items in silk producing a worthless gift (but a gift nonetheless) for a female. We studied the degree of individual behavioural differences by allocating males (n = 36) to one of the two groups. In the “Worthless” group, no prey items were available, while in the “Nutritive-Worthless” group, males had access to a live housefly and could offer the female a nutritive prey gift. In both groups, males could also offer a female either no gift or a worthless gift produced from a mealworm exuviae. We let males’ court individual females over five consecutive trials and examined the differences by using an analysis of repeatability. We found that males were plastic in their decision making, presenting the female either a prey or an inedible item for the gift in the Nutritive-Worthless group. But, they were more likely to present a worthless gift in the Worthless group and when they were larger. However, rather than worthless gift-giving being a cheap tactic, males highly invest in silk when producing such gifts. Our data suggest males can adjust their behaviour differentially investing in the gift content or in the silk wrapping according to prey availability and their own size. This content quality – silk-wrapping trade-off is probably determining the final fitness success of these mating tactics in P. ornata