Kalbitzer Urs, Heistermann Michael, Cheney Dorothy, Seyfarth Robert, Fischer Julia
Cognitive Ethology Laboratory, German Primate Center (DPZ), Kellnerweg 4, 37077 Göttingen, Germany; Department of Anthropology and Archaeology, University of Calgary, 2500 University Dr. N.W., Calgary, Alberta T2N 1N4, Canada.
Endocrinology Laboratory, German Primate Center (DPZ), Kellnerweg 4, 37077 Göttingen, Germany.
Horm Behav. 2015 Sep;75:100-10. doi: 10.1016/j.yhbeh.2015.08.013. Epub 2015 Sep 5.
In multi-male, multi-female groups of mammals, males usually compete aggressively over access to females. However, species vary in the intensity of male contest competition, which has been linked to differences in testosterone and glucocorticoid profiles. Chacma (Papio ursinus) and Guinea (P. papio) baboons constitute an intriguing model to examine variation in male competition and male endocrine correlates, because of the differences in their social systems. Chacma baboons live in stable female-bonded groups with linear male dominance hierarchies and a high male mating skew, whereas Guinea baboons live in male-bonded, multi-level societies. We recorded male behavior and assayed testosterone (fT) and glucocorticoid metabolite (fGC) levels from fecal samples in one population of each species. Male chacma baboons were more frequently involved in agonistic interactions, and dominance relationships were more consistent than in Guinea baboons, where we could not detect linear hierarchies. Notably, male chacma baboons were also more aggressive towards females, indicating an overall higher aggressiveness in this species. In contrast, male Guinea baboons showed higher levels of affiliative interactions and spatial tolerance. High-ranking and consorting male chacma baboons showed elevated fGC levels and also tended to show elevated fT levels, but there was no effect of consortship in Guinea baboons. Agonism was not related to hormone levels in either species. Thus, predictors of fT and fGC levels in Guinea baboons seem to differ from chacma baboons. Our results support the view that different social systems create differential selection pressures for male aggression, reflected by different hormone profiles.
在哺乳动物的多雄多雌群体中，雄性通常会为获得与雌性交配的机会而激烈竞争。然而，不同物种的雄性竞争强度存在差异，这与睾酮和糖皮质激素水平的差异有关。由于查卡玛狒狒（Papio ursinus）和几内亚狒狒（P. papio）的社会系统不同，它们构成了一个研究雄性竞争及其内分泌相关因素差异的有趣模型。查卡玛狒狒生活在稳定的、以雌性为纽带的群体中，雄性具有线性的优势等级制度，且雄性交配偏斜度较高；而几内亚狒狒生活在以雄性为纽带的多层次社会中。我们记录了每个物种一个种群中雄性的行为，并从粪便样本中检测了睾酮（fT）和糖皮质激素代谢物（fGC）的水平。与几内亚狒狒相比，查卡玛狒狒雄性更频繁地参与争斗互动，优势关系也更稳定，在几内亚狒狒中我们无法检测到线性等级制度。值得注意的是，查卡玛狒狒雄性对雌性也更具攻击性，表明该物种总体攻击性更高。相比之下，几内亚狒狒雄性表现出更高水平的亲和互动和空间容忍度。地位高且正在交配的查卡玛狒狒雄性fGC水平升高，fT水平也往往升高，但在几内亚狒狒中交配状态没有影响。在这两个物种中，争斗行为均与激素水平无关。因此，几内亚狒狒中fT和fGC水平的预测因素似乎与查卡玛狒狒不同。我们的结果支持这样一种观点，即不同的社会系统对雄性攻击行为产生不同的选择压力，这体现在不同的激素水平上。
