Department of Biology, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604, USA.
Department of Ecology, Evolution, and Behavior, University of Minnesota - Twin Cities, 1479 Gortner Ave, St. Paul, MN 55108, USA; Graduate Program in Neuroscience, University of Minnesota - Twin Cities, 321 Church Street SE, Minneapolis, MN 55455, USA.
Horm Behav. 2019 Feb;108:62-72. doi: 10.1016/j.yhbeh.2019.01.001. Epub 2019 Jan 16.
In seasonal breeders, there are behavioral, endocrine, and neural adaptations that promote the sexual receptivity of females and tune their sensory systems to detect and discriminate among advertising males and to successfully copulate. What happens immediately after this key life history event is unclear, but this transitional moment offers a window into the mechanisms that remodel sexual phenotypes. In this study of wild female Cope's gray treefrogs (Hyla chrysoscelis), we tested the hypothesis that oviposition results in a suite of coordinated changes in the sexual phenotype. Specifically, we predicted that sexual receptivity and discrimination behaviors would decline along with circulating concentrations of steroid hormones (corticosterone, estradiol, testosterone) and auditory sensitivity to the acoustic frequencies emphasized in male advertisement calls. We conducted these trait measurements before and after oviposition (ca. 24-h period). There was a 100% decrease in behavioral responsiveness after oviposition, and the concentrations of all three steroids plummeted during this brief window of time, especially testosterone. Moreover, higher concentrations of corticosterone-an important component of the endocrine stress response-were associated with longer response latencies, suggesting that adrenal hormones should be considered in future studies on the hormonal basis of mate choice. Counter to our prediction, auditory sensitivity increased following oviposition, and the amplitude of the auditory brainstem response was influenced by concentrations of estradiol. In pre-oviposition females auditory sensitivity diminished with increasing estradiol concentrations, while sensitivity increased with increasing estradiol concentrations in post-oviposition females, suggesting non-linear estrogenic modulation of peripheral auditory neural recruitment. Overall, our results indicate that there is considerable remodeling of behavioral output following oviposition that co-occurs with changes in both endocrine and sensory physiology.
在季节性繁殖者中，存在行为、内分泌和神经适应，这些适应促进了雌性的性接受能力，并调整了它们的感觉系统，以检测和区分广告雄性，并成功交配。在这个关键的生活史事件之后立即发生的事情尚不清楚，但这个过渡时刻为重塑性表型的机制提供了一个窗口。在对野生雌性 Cope 的灰色树蛙 (Hyla chrysoscelis) 的这项研究中，我们检验了这样一个假设，即产卵会导致性表型发生一系列协调的变化。具体来说，我们预测，性行为接受能力和辨别行为会随着循环中类固醇激素（皮质酮、雌二醇、睾酮）的浓度以及对雄性广告叫声中强调的听觉频率的敏感性下降而下降。我们在产卵前和产卵后（约 24 小时周期）进行了这些特征测量。产卵后，行为反应性下降了 100%，而所有三种类固醇的浓度在这个短暂的时间窗口内急剧下降，尤其是睾酮。此外，皮质酮浓度较高——内分泌应激反应的一个重要组成部分——与反应潜伏期较长有关，这表明在未来关于配偶选择的激素基础的研究中，应考虑肾上腺激素。与我们的预测相反，产卵后听觉敏感性增加，听觉脑干反应的幅度受雌二醇浓度的影响。在产卵前的雌性中，听觉敏感性随雌二醇浓度的增加而降低，而在产卵后的雌性中，听觉敏感性随雌二醇浓度的增加而增加，这表明雌激素对周围听觉神经募集的非线性调节。总的来说，我们的研究结果表明，在产卵后，行为输出有相当大的重塑，这与内分泌和感觉生理学的变化同时发生。
