Female spiders ignore condition-dependent information from nuptial gift wrapping when choosing mates

In many species, condition-dependent secondary sexual traits are important for female choice. In the spider Pisaura mirabilis, males offer females a nuptial gift (prey wrapped in silk) during courtship. Gift construction may involve high costs for males, and those in low condition invest less time and silk in wrapping the prey. We investigated how male condition and gift wrapping affect male reproductive success and whether females use the wrapped gift as an honest indicator of male condition. We experimentally manipulated male condition (satiated and starved males) and gift wrapping (well- and poorly wrapped gifts) and carried out experiments in a fully factorial design. We found that males in good condition were more successful in obtaining matings and obtained longer copulations than males in poor condition. In contrast, gift wrapping did not affect female mate choice. Only good-condition males obtained offspring. Gift wrapping is an honest indicator of male condition, but in spite of this females did not use this information in mate choice. We argue that because gift wrapping mainly functions to promote male interests, good-condition males would also be better at cheating the female, for example using wrapping to hide a worthless gift. Females should therefore evolve to ignore the wrapping information and instead base their mate choice decision on male traits that unequivocally benefit their own reproductive success. Our results are consistent with this prediction, as females discriminated males based only on their actual feeding condition, and this choice provided them with direct reproductive benefits. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.