Sexual coercion in a territorial salamander:

Slide 1: Sexual coercion in a territorial salamander: Females punish socially polygynous  male partners by Ethan D. Prosen, Robert Jaeger, & Danielle Lee

Plethodon cinereus, the red-backed salamander, inhabit the leaf litter of the forest floor across eastern North America. They have a complex social system; they use displays and pheromones to communicate and gather information. Individual�s of both sexes are territorial and their courtship is in the autumn and the spring. Some salamanders are monogamous, while others are polygynous. Background: Sexual intimidation is when one sex aggressively punishes the other sex that refuse to mate with them or who merely associate with members of the opposite sex. Males are typically the ones to use punishment to coerce females into social monogamy. Hypothesis 1: Female red-backed salamanders will be aggressive towards polygynous male partners because of following conditions Some members engaging in social monogamy and sharing territories during the noncourtship season. Females food, yolking ova, is limited in her territory. Females are aggressive towards territorial intruding females. Sexes are not significantly different in size. Hypothesis 2: Females will not be significantly more aggressive towards socially polygynous male strangers than towards socially na�ve male strangers. Materials and Methods: Salamanders were collected near Mountain lake Biological Station in Virginia. Two identical sets of experiments were performed; one with the fall season salamanders and one with the spring season salamanders. In each experiment: Treatment 1: Socially polygynous male partner (SPP) A male partner was placed in a single fem ales territory for 6 days and then placed back with his female partner. Treatment 2: Socially monogamous male partner (SMP) A male partner was placed alone for 6 days and then placed back with his female partner. Treatment 3: Socially na�ve male stranger (SNS) A socially na�ve male stranger was placed with a single female. Treatment 4: Socially polygynous male stranger (SPS) A socially polygynous male stranger was placed with a single female. Behavioral Patterns Recorded: Seconds spent in all-trunk-raised threat posture Touching the other salamander Number of bites and the number of nose taps Statistical Analyses Used a two-tailed Mann-Whitney U Tests to compare the behavioral patterns between treatments 1 and 2, and separately between treatments 3 and 4. Results: Autumn Courtship Season: Partners SPP vs. SMP With SPP, Females spent more time in ATR posture less time touching nose-tapped the substrate bit partner more often Autumn Courtship Season: Strangers SPS vs. SMS Females spent more time in ATR posture in response to SPS relative to SNS but was not significant. Females showed no other significant behavioral differences. Spring Courtship Season: Partners SPP vs. SMP Females showed no significant differences in any of the behavioral responses recorded Spring Courtship Season: Strangers SPS vs. SMS There were no significant differences in female responses. Discussion: In Autumn paired Females were significantly more threatening and directed more bites towards SPP relative to SMP. In Spring Females didn�t distinguish between SPP and SMP. Females didn�t punish SPP. Females priorities changed: preoccupied with locating suitable nesting sites Data supports the hypothesis that females do punish SPP, at least early in the courtship period. Paired females punished SPP males more than single females. Female Benefits: Female aggression may help in gathering resources necessary for reproduction. Polygynous males may return with another female and allow her to forage in his territory, which could directly impact the residential female�s reproductive success. Female red-back punishing a male red-back