Copulatory plugs in the Iberian Rock Lizard do not prevent insemination by rival males

Abstract

Summary Iberian Rock Lizard (Lacerta monticola, Boulenger 1905) males produce copulatory plugs that harden and adhere firmly inside the female cloaca immediately after copulation and occlude both oviductal openings. To determine whether plugs reduce the chance of females being inseminated by rival males, two hypotheses were tested: (i) that plugs reduce female attractiveness and/or receptivity to rival males; and (ii) that plugs function as ‘chastity belts’. There was no evidence to support either hypothesis. Neither male initiation of copulations and female termination of male copulation attempts, nor male insemination success differed significantly between trials in which males were presented with females without a plug and with females with a plug deposited by a different male 1, 3 and 6 or more hours earlier, nor between females without and with a plug. Several hypotheses for the function of Iberian Rock Lizard plugs are discussed. Since rival males were frequently able to displace a plug in the female cloaca, our results are consistent with a ‘sperm protection’ function of male postcopulatory mate guarding in squamate reptiles, but this remains to be tested.