Cavigelli S A, Pereira M E
Department of Psychology, University of Chicago, Illinois 60637, USA.
Horm Behav. 2000 May;37(3):246-55. doi: 10.1006/hbeh.2000.1585.
The challenge hypothesis (J. C. Wingfield, R. E. Hegner, B. G. Ball, and A. M. Duffy, 1990, Am. Nat. 136, 829-846) proposes that in birds, reptiles, and fish, "the frequency or intensity of reproductive aggression as an effect of T[estosterone] is strongest in situations of social instability, such as during the formation of dominance relationships, the establishment of territorial boundaries, or challenges by a conspecific male for a territory or access to mates" (p. 833). To determine the extension of this hypothesis to mammalian species, we tested predictions of the hypothesis in a nonpaternal, seasonal breeding, prosimian primate (ring-tailed lemurs, Lemur catta). Semi-free-ranging males were studied during periods of social stability (premating period) and instability (mating period). The annual mating season consists of several days during which males fight for access to promiscuous group females as each individually becomes sexually receptive for 1 day. Male rates of aggression were compared to fecal testosterone levels within premating and mating periods. In the premating period male rate of aggression was not significantly correlated with testosterone level. By contrast, during the mating season testosterone and aggression levels were positively and significantly correlated. However, on days just preceding estrus, male rate of aggression was not significantly correlated with testosterone, but on days of estrus, when aggressive challenges peaked sharply, testosterone and aggression were highly positively correlated. These results suggest that the challenge hypothesis applies to mammals as well as to birds, reptiles, and fish. In addition, elevations in testosterone were tightly circumscribed around days of estrus, suggesting a compromise between costs and benefits of elevated testosterone levels.
挑战假说（J.C.温菲尔德、R.E.黑格纳、B.G.鲍尔和A.M.达菲，1990年，《美国博物学家》第136卷，第829 - 846页）提出，在鸟类、爬行动物和鱼类中，“作为睾酮作用结果的繁殖攻击频率或强度在社会不稳定的情况下最强，比如在优势关系形成期间、领地边界确立期间，或者同种雄性为争夺领地或接近配偶而发起挑战时”（第833页）。为了确定这一假说在哺乳动物物种中的适用范围，我们在一种非父系、季节性繁殖的原猴灵长类动物（环尾狐猴，狐猴属）中对该假说的预测进行了测试。在社会稳定期（交配前期）和不稳定期（交配期）对半放养的雄性进行了研究。年度交配季节持续数天，在此期间，随着每只雌性个体分别进入为期1天的性接受期，雄性会为接近滥交群体中的雌性而争斗。比较了交配前期和交配期内雄性的攻击率与粪便中的睾酮水平。在交配前期，雄性攻击率与睾酮水平无显著相关性。相比之下，在交配季节，睾酮水平与攻击水平呈显著正相关。然而，在发情期前几天，雄性攻击率与睾酮无显著相关性，但在发情当天，当攻击性挑战急剧达到峰值时，睾酮与攻击呈高度正相关。这些结果表明，挑战假说不仅适用于鸟类、爬行动物和鱼类，也适用于哺乳动物。此外，睾酮水平的升高在发情期前后受到严格限制，这表明在睾酮水平升高的成本和收益之间存在一种平衡。
