Relationship between androgens, environmental factors and reproductive behavior in male white rhinoceros (Ceratotherium simum simum)
Relationship between androgens, environmental factors and reproductive behavior in male white rhinoceros (Ceratotherium simum simum)
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DOI：
10.1016/j.yhbeh.2003.08.001
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发表时间：
2004-01-01
影响因子：
3.5
通讯作者：
Dehnhard, M
中科院分区：
文献类型：
--
作者：
Kretzschmar, P;Ganslosser, U;Dehnhard, M
我们对自由放养的雄性白犀牛的内分泌活动进行了纵向研究。一种用于测量粪便中雄激素的酶免疫分析法被开发出来并得到验证，表明它可以用于研究睾丸活性。我们确定了两种类似于睾酮和二氢睾酮的粪便代谢物。几条线索的证据表明，这些代谢物清楚地反映睾丸活动。首先，用合成GnRH刺激睾丸活动，导致治疗1天后粪便中雄激素代谢物浓度增加156%。其次，雄激素代谢物浓度随着犀牛性成熟而增加，最后，血浆中睾酮浓度与粪便中雄激素代谢物浓度存在相关性。使用我们开发的方法，有可能确定雄激素代谢物浓度，行为和环境因素之间是否存在关系。与少雨或无雨的月份（3 - 8月）相比，在高降雨量的月份（9 - 2月），成年领地雄性（n = 5）雄激素代谢物浓度升高。浓度的增加与雨季的开始一致，表明繁殖有季节性趋势。这一趋势得到了行为观察的证实，在雄激素代谢物浓度增加的头4个月里，雌性的受孕频率更高，两性之间的冲突也更多，这反映了交配期间两性之间最初的攻击。同样明显的是，与单独交配相比，与接受交配的雌性同行的雄性粪便雄激素代谢物浓度更高。升高的水平可能是由女性在场引起的。(C) 2003 Elsevier Inc.版权所有。
We conducted a longitudinal study of the endocrine activity of free-range male white rhinos. An enzyme immunoassay to measure androgens in the feces was developed and validated to show that it can be used to study testicular activity. We identified two fecal metabolites similar to testosterone and dihydrotestosterone. Several lines of evidence suggest that these metabolites clearly reflect testicular activity. Firstly, the stimulation of testicular activity with synthetic GnRH caused a 156% increase in androgen metabolite concentrations in the feces 1 day after treatment. Secondly, androgen metabolite concentrations increased with sexual maturity in rhinos, and finally there was a correlation between testosterone concentrations in plasma and androgen metabolite concentrations in feces. Using the method that we developed, it was possible to establish whether a relationship exists between androgen metabolite concentrations, the behavior and environmental factors. Adult territorial males (n = 5) had elevated androgen metabolite concentrations during months of high rainfall (September-February) compared to months of little or no rainfall (March-August). The increase in concentrations coincided with the beginning of the rainy season, suggesting a seasonal trend in reproduction. This trend was confirmed by behavior observations showing both a higher frequency of conceptions within the first 4 months of increased androgen metabolite concentrations, and a higher number of inter-sexual conflicts, reflecting the initial aggression between the sexes during the consort period. It was also evident that males accompanying a receptive female had higher fecal androgen metabolite concentrations compared to being alone. The elevated levels were likely induced by female presence. (C) 2003 Elsevier Inc. All rights reserved.