Arginine vasotocin activates aggressive calls during paternal care in the Puerto Rican coquí frog, Eleutherodactylus coqui

Abstract

The Puerto Rican coquí frog, Eleutherodactylus coqui, is a directly developing frog that exhibits male territoriality and paternal behaviors. Male frogs also produce advertisement and aggressive vocalizations or calls. Territorial males emit advertisement calls to delineate territories and attract mates. Paternal males guard and brood the directly developing embryos during embryogenesis and up to five days after hatching; advertisement calling is normally absent or infrequent during paternal care. Territorial and paternal males commonly produce aggressive calls during agonistic situations. The neuropeptide, arginine vasotocin (AVT), has been shown to promote calling in anurans, including E. coqui. The objective of this study was to determine if exogenous AVT promotes calling and territorial behavior in paternal males and if it promotes males to abandon their offspring. Injections (IP) of AVT were given to paternal males immediately before the scotoperiod. Frogs were monitored for at least four hours after the injection and the following morning for calling activity and abandonment of egg clutches. AVT-injected males showed a dramatic and significant increase in aggressive calls compared to control males (saline injections). Exogenous AVT did induce advertisement calling in some paternal males but did not significantly elevate paternal males to territorial status nor did it significantly induce abandonment of eggs/embryos. In conclusion, the type of vocalization that AVT activates in E. coqui depends upon the reproductive state of the male and the social environment that surrounds the male.