Goymann Wolfgang, Flores Dávila Pamela
Max-Planck-Institut für Ornithologie, Abteilung für Verhaltensneurobiologie, Eberhard-Gwinner-Strasse 6a, 82319 Seewiesen, Germany
Max-Planck-Institut für Ornithologie, Abteilung für Verhaltensneurobiologie, Eberhard-Gwinner-Strasse 6a, 82319 Seewiesen, Germany.
Proc Biol Sci. 2017 Jun 28;284(1857). doi: 10.1098/rspb.2017.0632.
A long-standing tenet of evolutionary endocrinology states that testosterone mediates the life-history trade-off between mating and paternal care. However, the support for a role of testosterone in suppressing paternal care is mixed: implantation studies in birds suggest that high-level testosterone implants suppress paternal care, but circulating levels of testosterone and paternal care are typically not correlated. Because any trade-off in real life must be realized with hormone levels that are within an individual's reaction norm, it is crucial to show that natural changes in the hormone can modulate behaviour. Here, we used GnRH-injections to alter testosterone levels of free-living male black redstarts within each individual's hormonal reaction norm: individuals experiencing a short-term peak in testosterone resumed feeding their offspring later and showed a stronger suppression of offspring-feeding behaviour than control males. For the first time, this study demonstrated that short-term peaks in testosterone within the hormonal reaction norm of individuals can suppress paternal behaviour. Our findings reconcile previous seemingly contradictive effects that testosterone implants had on paternal care and the absence of correlations between circulating testosterone levels and paternal care, and demonstrate that the differential production of testosterone within the hormonal reaction norm of single individuals can indeed function as a mechanism to mediate a potential trade-off between mating and parenting. On a broader note, our results suggest that natural and short peaks in testosterone can elicit adaptive behavioural changes.
进化内分泌学的一个长期信条认为，睾酮介导了交配与亲代抚育之间的生活史权衡。然而，关于睾酮在抑制亲代抚育方面作用的证据并不一致：鸟类的植入研究表明，高剂量睾酮植入会抑制亲代抚育，但睾酮的循环水平与亲代抚育通常并无关联。由于现实生活中的任何权衡都必须通过个体反应规范内的激素水平来实现，因此证明激素的自然变化能够调节行为至关重要。在此，我们通过注射促性腺激素释放激素（GnRH）来改变自由生活的雄性黑红尾鸲体内的睾酮水平，使其处于每个个体的激素反应规范内：睾酮出现短期峰值的个体比对照雄性个体更晚恢复喂养后代，并且对后代喂养行为的抑制更强。本研究首次证明，个体激素反应规范内的睾酮短期峰值能够抑制亲代行为。我们的研究结果调和了先前睾酮植入对亲代抚育产生的看似矛盾的影响，以及循环睾酮水平与亲代抚育之间缺乏相关性的问题，并证明单个个体激素反应规范内睾酮的差异产生确实可以作为一种机制，来介导交配与养育后代之间潜在的权衡。更广泛地说，我们的结果表明，睾酮自然且短暂的峰值能够引发适应性行为变化。
