Steroid levels following experimentally induced mating in gray treefrogs during 2024 breeding season (Carver Park Reserve, MN)

Abstract

During amplexus, male frogs clasp a female for several hour prior to gamete release. In this experiment, we tested the hypothesis that amplexus can cause changes in circulating levels of steroid hormones in Cope's gray tree frogs ('Hyla chrysoscelis'). Frogs were collected in breeding ponds in Carver Park Reserve in Minnesota in May and June of 2024. An amplexed pair and two single males were collected in quick succession and brought to the edge of the pond for each experimental trial. In each trial, we quantified levels of testosterone, estradiol, and corticosterone after 90 minutes in four treatment groups: males allowed to enter amplexus with a newly provided female ("amplexus induced"), paired males removed from their mate ("amplexus terminated"), unpaired control males, and the female that was removed from the amplexus terminated male and given to the amplexus induced male.