OPPORTUNISTIC MALES AND FEMALE REMATING IN A SEX ROLE REVERSED SPIDER

AISENBERG, ANITA; BOLLATTI, FEDRA; PERETTI, ALFREDO VICENTE

Congreso; 110th Annual Meeting of the German Zoological Society (DZG); 2017

Sexual Selection is a powerful evolutive force which acts on the abilities of one sex to accessing potential pairs. In this scenario, conspecifics intrasexual opponents could find different solutions to reproductive competition, which will evolve in alternative reproductive tactics towards the same functional end. Allocosa senex is a nocturnal sand-dwelling spider which shows reversal in sex roles and sexual size dimorphism: conversely to what is typical in spiders, females are smaller than males and they are the mobile sex that searches for males and initiates courtship. According to previous studies, males construct long burrows and stay inside expecting female?s visits. However, as males donate their burrows to females after mating, when they emerge during the night to feed they can potentially bump into mated females inside the burrows donated by previous males. Our objective was to test if males of A. senex can detect mated females inside other male?s burrows and if they are accepted for mating by those females. Virgin males were placed in a terrarium 48 h before the trial to allow burrow construction. Each experience (n=7) begun when a virgin female was introduced into that terrarium, and ended after the copulation was concluded. Once the trial was finished, the male was removed and the female was allowed to remain inside the donated burrow for 3-5 days. After that, a second male was introduced to the terrarium and courting and mating behaviors were recorded. Preliminary results show that second males can detect and court mated females staying in donated burrows in a high percentage (71%), while in 43% cases even they mate. These results suggest that males of A. senex can modulate their reproductive tactics adopting an opportunistic strategy using those burrows dug by others males, which allows them to mate with a mated female on an alien male?s burrow avoiding the great investment that implies burrow digging.