Goymann Wolfgang
Max-Planck-Institut für Ornithologie, Abteilung für Verhaltensneurobiologie, Evolutionary & Environmental Physiology Lab, Eberhard-Gwinner-Str. Haus 6a, D-82319 Seewiesen, Germany.
Gen Comp Endocrinol. 2009 Sep 1;163(1-2):149-57. doi: 10.1016/j.ygcen.2008.11.027. Epub 2008 Dec 7.
Most seasonally reproducing vertebrates show pronounced changes in testosterone levels throughout the year. The Challenge Hypothesis [Wingfield, J.C., Hegner, R.E., Dufty, A.M., Ball, G. F., 1990. The "challenge hypothesis": theoretical implications for patterns of testosterone secretion, mating systems, and breeding strategies. Am. Nat. 136, 829-846] predicts that seasonal patterns in circulating androgen concentrations vary as a function of mating system, male-male aggression and paternal care. In most comparative studies, the predictions of the Challenge Hypothesis have been tested primarily by calculating the ratio between breeding peak and breeding baseline testosterone concentrations, using this ratio as a proxy for the effect that social interactions have on testosterone levels (androgen responsiveness R). Recently, we suggested that it is preferable to separate the seasonal testosterone response (R(season)) from the androgen responsiveness to male-male interactions (R(male-male)), as these two measures do not correlate and can differ both in magnitude and direction [Goymann, W., Landys, M.M., Wingfield, J.C., 2007. Distinguishing seasonal androgen responses from male-male androgen responsiveness-revisiting the Challenge Hypothesis. Horm. Behav. 51, 463-476]. Here, I discuss several methodological and ecological factors that may explain why R(season) and R(male-male) differ. Furthermore, I describe three other kinds of androgen responsiveness, namely the androgen responsiveness of males to receptive females (R(male-female)), to non-social environmental cues (R(environment)), and the potential androgen responsiveness (R(potential)). The latter is measured before and after an injection of gonadotropin releasing hormone (GnRH), which typically leads to a maximal release of testosterone from the testes. I argue that separation of different kinds of androgen responsiveness and putting them into context with the natural history and ecology of a study species may help to better understand variations in androgen responsiveness to social and non-social environmental factors. On an ultimate level this may help to better understand the benefits and costs of increasing, or not increasing testosterone concentrations during social interactions. Proximately, this will aid in a more complete understanding of the mechanisms by which testosterone regulates behavioral traits and by which behavior feeds back on hormone levels.
大多数季节性繁殖的脊椎动物全年的睾酮水平都有显著变化。挑战假说[温菲尔德，J.C.，黑格纳，R.E.，达菲，A.M.，鲍尔，G.F.，1990年。“挑战假说”：睾酮分泌模式、交配系统和繁殖策略的理论启示。《美国博物学家》136卷，829 - 846页]预测，循环雄激素浓度的季节性模式会因交配系统、雄性间攻击行为和父性照料而有所不同。在大多数比较研究中，挑战假说的预测主要是通过计算繁殖高峰期与繁殖基线期睾酮浓度的比值来检验的，用这个比值作为社会互动对睾酮水平影响（雄激素反应性R）的代理指标。最近，我们提出最好将季节性睾酮反应（R(季节)）与雄性间互动的雄激素反应性（R(雄性 - 雄性)）区分开来，因为这两种测量方法不相关，而且在大小和方向上都可能不同[戈伊曼，W.，兰迪斯，M.M.，温菲尔德，J.C.，2007年。区分季节性雄激素反应与雄性间雄激素反应性——重新审视挑战假说。《激素与行为》51卷，463 - 476页]。在此，我讨论了几个可能解释R(季节)和R(雄性 - 雄性)为何不同的方法学和生态学因素。此外，我还描述了其他三种雄激素反应性，即雄性对处于接受期雌性的雄激素反应性（R(雄性 - 雌性)）、对非社会环境线索的雄激素反应性（R(环境)）以及潜在雄激素反应性（R(潜在)）。后者是在注射促性腺激素释放激素（GnRH）前后进行测量的，GnRH通常会导致睾丸中睾酮的最大释放。我认为区分不同类型的雄激素反应性，并将它们与研究物种的自然史和生态学联系起来，可能有助于更好地理解雄激素对社会和非社会环境因素反应性的变化。从终极层面来看，这可能有助于更好地理解在社会互动中增加或不增加睾酮浓度的益处和成本。从近因层面来看，这将有助于更全面地理解睾酮调节行为特征的机制以及行为对激素水平的反馈机制。
