Male Iberian rock lizards (Lacerta monticola) produce copulatory plugs that adhere firmly inside ... more Male Iberian rock lizards (Lacerta monticola) produce copulatory plugs that adhere firmly inside the female cloaca and occlude both oviducts. These plugs do not prevent rival male insemination, as they neither reduce female attractiveness or receptivity to rival males nor do they function as "chastity belts". Prior to copulation, males bite various regions of the female body, including the cloacal region. A previous plug in the female cloaca is expelled only after rival male intromission. We hypothesized that: (1) such male pre-copulatory behaviours function to loosen plug adherence to the female cloaca, thereby facilitating intromission, and that (2) the hemipenis plays a role in displacing a previous plug prior to the delivery of a new plug. Neither of these hypotheses was supported. Instead, our results indicate that rival males can intromit the hemipenis past a previous plug in the female cloaca and deliver their own plug underneath it. Consequently, previous plugs are pushed away from the oviductal openings and even dislodged from the female cloaca. Copulation duration was determined both by the time used by males to deliver a plug and by the fact that males prolonged copulation beyond plug delivery. There seemed to be sexual conflict over prolonged copulation, which was resolved by the male/female headlength ratio. The adaptive value of Iberian rock lizard copulatory plugs and prolonged copulation in Iberian rock lizards is discussed in the context of sperm competition.
Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards... more Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards. Here, we hypothesised that juvenile Iberian rock lizards (Lacerta (=Iberolacerta) monticola) use substrate-borne conspecific faecal chemicals to assess the social environ-ment and base their spatial decisions. To test this hypothesis, we prepared chemical stimuli by dissolving faeces in an organic solvent (dichloromethane, DCM) and conducted chemosensory trials where we quantified latency to the first tongue flick (TF) and TF rates when young captive-borne juveniles were placed in an arena compart-ment whose substrate was labelled by (1) a control (DCM), (2) their own faecal chemicals, (3) faecal chemicals of another juvenile, (4) faecal chemicals of an adult female or (5) faecal chemicals of an adult male. Following TF observations, we removed a partition that separated the labelled compartment from a chemically unlabelled one, and recorded for 5 min when juveniles first crossed to th...
Socially dominant males often signal their status to rival males and/or females. We tested the hy... more Socially dominant males often signal their status to rival males and/or females. We tested the hypotheses that Lacerta monticola femoral gland secretions and copulatory plugs convey chemical information about male identity and dominance status. We estimated male dominance status by staging male-male agonistic encounters in a neutral arena. We then conducted two experiments to compare male tongue-flick behavior toward chemical stimuli consisting of cotton swabs bearing (1) deionized water (control), the lizard's own femoral secretions, and the femoral secretions of another male and (2) phosphate-buffered saline solution (control), the lizard's own plug products, and the plug products of another male. Results indicate that males discriminated their own femoral secretions and plugs from those of other males. They also discriminated morphological attributes of other males that were associated with dominance status based on chemical cues arising from femoral secretions and discriminated the dominance status of other males based on chemical cues arising from the plugs. Femoral secretions that convey information about male identity and dominance status may be hypothesized to function in the establishment of L. monticola dominance hierarchies through scent-marking of territories. We suggest that copulatory plugs and femoral secretions may allow males to scent-mark the female body and postulate that this behavior may influence male and female reproductive decisions under selective pressures of sperm competition.
Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards... more Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards. Here, we hypothesised that juvenile Iberian rock lizards (Lacerta (=Iberolacerta) monticola) use substrate-borne conspecific faecal chemicals to assess the social environment and base their spatial decisions. To test this hypothesis, we prepared chemical stimuli by dissolving faeces in an organic solvent (dichloromethane, DCM) and conducted chemosensory trials where we quantified latency to the first tongue flick (TF) and TF rates when young captive-borne juveniles were placed in an arena compartment whose substrate was labelled by (1) a control (DCM), (2) their own faecal chemicals, (3) faecal chemicals of another juvenile, (4) faecal chemicals of an adult female or (5) faecal chemicals of an adult male. Following TF observations, we removed a partition that separated the labelled compartment from a chemically unlabelled one, and recorded for 5 min when juveniles first crossed to the unlabelled compartment and total time spent in the labelled compartment. Each juvenile was tested with all stimuli in a randomised order. In addition, juveniles belonged to different families and were unrelated to and unfamiliar with faeces donors. Taken together, TF and spatial responses toward stimuli indicate that juveniles discriminated between faecal chemicals of conspecific juveniles, adult females and males, and that they avoided remaining in substrates labelled by adult male faecal chemicals. We suggest that juveniles assess the social environment based on conspecific faecal chemicals thus avoiding aggression and cannibalistic risks undertaken from encounters with adult males.
Sperm competition selects for opposing male defensive and offensive reproductive traits, and its ... more Sperm competition selects for opposing male defensive and offensive reproductive traits, and its outcome may be determined by the effectiveness to which one trait has evolved to out-compete the other. We tested the effectiveness of a first male plug physical interference with a second male insemination (defence) vs the effectiveness of plug and associated sperm displacement by a second male (offence) on the outcome of sperm competition in Iberian rock lizards. We conducted a double mating experiment where we compared the proportion of eggs per clutch fertilised by the same second males (against the same first males) when they copulated with females 30 min (first male plug adhered firmly inside the female cloaca) and 4 h (first male plug loosely adhered or shed from the female cloaca) after first males. We found that second males fertilised the majority of the eggs per clutch in the 30-min treatment, whereas fertilisations were equally shared between the two males in the 4-h treatment. These results show that plugs have little defensive effectiveness, and thus, do not assure high first male fertilisation success. Instead, sperm displacement appears to be associated with plug displacement. That is, because sperm embedded in first male plugs, and displaced from competition for fertilisations by second males, is expected to increase in number with decreasing time allowed for female sperm transport, second males thus enjoy higher fertilisation success. This study shows that offensive plug displacement out-competes plug defensive role in Iberian rock lizards. Moreover, it reveals sperm displacement as a novel sperm competition mechanism in reptiles.
1. Iberian Rock Lizard (Lacerta monticola , Boulenger 1905) males produce copulatory plugs that h... more 1. 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. 2. 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'. 3. 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. 4. 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.
Male Iberian rock lizards (Lacerta monticola) produce copulatory plugs that adhere firmly inside ... more Male Iberian rock lizards (Lacerta monticola) produce copulatory plugs that adhere firmly inside the female cloaca and occlude both oviducts. These plugs do not prevent rival male insemination, as they neither reduce female attractiveness or receptivity to rival males nor do they function as "chastity belts". Prior to copulation, males bite various regions of the female body, including the cloacal region. A previous plug in the female cloaca is expelled only after rival male intromission. We hypothesized that: (1) such male pre-copulatory behaviours function to loosen plug adherence to the female cloaca, thereby facilitating intromission, and that (2) the hemipenis plays a role in displacing a previous plug prior to the delivery of a new plug. Neither of these hypotheses was supported. Instead, our results indicate that rival males can intromit the hemipenis past a previous plug in the female cloaca and deliver their own plug underneath it. Consequently, previous plugs are pushed away from the oviductal openings and even dislodged from the female cloaca. Copulation duration was determined both by the time used by males to deliver a plug and by the fact that males prolonged copulation beyond plug delivery. There seemed to be sexual conflict over prolonged copulation, which was resolved by the male/female headlength ratio. The adaptive value of Iberian rock lizard copulatory plugs and prolonged copulation in Iberian rock lizards is discussed in the context of sperm competition.
Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards... more Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards. Here, we hypothesised that juvenile Iberian rock lizards (Lacerta (=Iberolacerta) monticola) use substrate-borne conspecific faecal chemicals to assess the social environ-ment and base their spatial decisions. To test this hypothesis, we prepared chemical stimuli by dissolving faeces in an organic solvent (dichloromethane, DCM) and conducted chemosensory trials where we quantified latency to the first tongue flick (TF) and TF rates when young captive-borne juveniles were placed in an arena compart-ment whose substrate was labelled by (1) a control (DCM), (2) their own faecal chemicals, (3) faecal chemicals of another juvenile, (4) faecal chemicals of an adult female or (5) faecal chemicals of an adult male. Following TF observations, we removed a partition that separated the labelled compartment from a chemically unlabelled one, and recorded for 5 min when juveniles first crossed to th...
Socially dominant males often signal their status to rival males and/or females. We tested the hy... more Socially dominant males often signal their status to rival males and/or females. We tested the hypotheses that Lacerta monticola femoral gland secretions and copulatory plugs convey chemical information about male identity and dominance status. We estimated male dominance status by staging male-male agonistic encounters in a neutral arena. We then conducted two experiments to compare male tongue-flick behavior toward chemical stimuli consisting of cotton swabs bearing (1) deionized water (control), the lizard's own femoral secretions, and the femoral secretions of another male and (2) phosphate-buffered saline solution (control), the lizard's own plug products, and the plug products of another male. Results indicate that males discriminated their own femoral secretions and plugs from those of other males. They also discriminated morphological attributes of other males that were associated with dominance status based on chemical cues arising from femoral secretions and discriminated the dominance status of other males based on chemical cues arising from the plugs. Femoral secretions that convey information about male identity and dominance status may be hypothesized to function in the establishment of L. monticola dominance hierarchies through scent-marking of territories. We suggest that copulatory plugs and femoral secretions may allow males to scent-mark the female body and postulate that this behavior may influence male and female reproductive decisions under selective pressures of sperm competition.
Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards... more Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards. Here, we hypothesised that juvenile Iberian rock lizards (Lacerta (=Iberolacerta) monticola) use substrate-borne conspecific faecal chemicals to assess the social environment and base their spatial decisions. To test this hypothesis, we prepared chemical stimuli by dissolving faeces in an organic solvent (dichloromethane, DCM) and conducted chemosensory trials where we quantified latency to the first tongue flick (TF) and TF rates when young captive-borne juveniles were placed in an arena compartment whose substrate was labelled by (1) a control (DCM), (2) their own faecal chemicals, (3) faecal chemicals of another juvenile, (4) faecal chemicals of an adult female or (5) faecal chemicals of an adult male. Following TF observations, we removed a partition that separated the labelled compartment from a chemically unlabelled one, and recorded for 5 min when juveniles first crossed to the unlabelled compartment and total time spent in the labelled compartment. Each juvenile was tested with all stimuli in a randomised order. In addition, juveniles belonged to different families and were unrelated to and unfamiliar with faeces donors. Taken together, TF and spatial responses toward stimuli indicate that juveniles discriminated between faecal chemicals of conspecific juveniles, adult females and males, and that they avoided remaining in substrates labelled by adult male faecal chemicals. We suggest that juveniles assess the social environment based on conspecific faecal chemicals thus avoiding aggression and cannibalistic risks undertaken from encounters with adult males.
Sperm competition selects for opposing male defensive and offensive reproductive traits, and its ... more Sperm competition selects for opposing male defensive and offensive reproductive traits, and its outcome may be determined by the effectiveness to which one trait has evolved to out-compete the other. We tested the effectiveness of a first male plug physical interference with a second male insemination (defence) vs the effectiveness of plug and associated sperm displacement by a second male (offence) on the outcome of sperm competition in Iberian rock lizards. We conducted a double mating experiment where we compared the proportion of eggs per clutch fertilised by the same second males (against the same first males) when they copulated with females 30 min (first male plug adhered firmly inside the female cloaca) and 4 h (first male plug loosely adhered or shed from the female cloaca) after first males. We found that second males fertilised the majority of the eggs per clutch in the 30-min treatment, whereas fertilisations were equally shared between the two males in the 4-h treatment. These results show that plugs have little defensive effectiveness, and thus, do not assure high first male fertilisation success. Instead, sperm displacement appears to be associated with plug displacement. That is, because sperm embedded in first male plugs, and displaced from competition for fertilisations by second males, is expected to increase in number with decreasing time allowed for female sperm transport, second males thus enjoy higher fertilisation success. This study shows that offensive plug displacement out-competes plug defensive role in Iberian rock lizards. Moreover, it reveals sperm displacement as a novel sperm competition mechanism in reptiles.
1. Iberian Rock Lizard (Lacerta monticola , Boulenger 1905) males produce copulatory plugs that h... more 1. 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. 2. 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'. 3. 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. 4. 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.
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