Fichtel Claudia, Kraus Cornelia, Ganswindt André, Heistermann Michael
Department of Behavioral Ecology and Sociobiology, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany.
Horm Behav. 2007 May;51(5):640-8. doi: 10.1016/j.yhbeh.2007.03.005. Epub 2007 Mar 21.
Studies in anthropoid primates and other mammals suggest that reproductive season, rank, reproductive skew, aggression received, and social support are the major factors influencing glucocorticoid output. In which way these are also affecting adrenal function in lemurid primates has been studied rarely. Here, we examine the influence of reproductive season and rank on glucocorticoid output in male sifakas (Propithecus verreauxi), a species characterized by high breeding seasonality, a hierarchy among males and extreme reproductive skew towards dominant males. We established a fecal assay for non-invasively monitoring adrenal activity and collected 315 fecal samples during the reproductive and birth season from 10 male sifakas living in 5 groups in Western Madagascar. We found a significant effect of season on glucocorticoid output, with males exhibiting higher fecal glucocorticoid levels during the reproductive compared to the birth season in conjunction with an increase in overall aggression rates during the former period. Moreover, our data indicate a significant effect of rank on adrenocortical activity with dominant males exhibiting higher glucocorticoid levels than subordinate males in the reproductive season. However, dominant males did not differ significantly in rates of initiated or received aggression and rates of affiliative behavior from subordinates but showed significantly lower rates of submission. Given their highly formalized dominance relationships, we conclude that higher glucocorticoid output in dominant males during the 4-month reproductive season is likely related to higher energetic demands necessary to cope with the challenges of male reproduction rather than to physical demands of increased fighting frequency to maintain dominance status. High rank in sifakas may thus carry high costs, which, however, may be outweighed by monopolization of almost all paternities. In sum, our data generally support the findings on the relationship between environmental and social factors and glucocorticoid output found in non-lemurid primates.
对类人猿灵长类动物和其他哺乳动物的研究表明，繁殖季节、等级地位、繁殖偏斜、遭受的攻击以及社会支持是影响糖皮质激素分泌的主要因素。这些因素如何影响狐猴灵长类动物的肾上腺功能，目前研究较少。在此，我们研究了繁殖季节和等级地位对雄性维氏冕狐猴（Propithecus verreauxi）糖皮质激素分泌的影响，该物种具有繁殖季节性强、雄性个体间存在等级制度以及繁殖高度偏向优势雄性的特点。我们建立了一种粪便检测方法，用于非侵入性监测肾上腺活动，并在繁殖和产仔季节从生活在马达加斯加西部5个群体中的10只雄性维氏冕狐猴身上收集了315份粪便样本。我们发现季节对糖皮质激素分泌有显著影响，与产仔季节相比，雄性在繁殖季节的粪便糖皮质激素水平更高，同时在此期间总体攻击率也有所增加。此外，我们的数据表明等级地位对肾上腺皮质活动有显著影响，在繁殖季节，优势雄性的糖皮质激素水平高于从属雄性。然而，优势雄性在发起或遭受攻击的频率以及亲和行为的频率方面与从属雄性没有显著差异，但表现出显著更低的屈服率。鉴于它们高度形式化的优势关系，我们得出结论，在4个月的繁殖季节中，优势雄性较高的糖皮质激素分泌可能与应对雄性繁殖挑战所需的更高能量需求有关，而不是与为维持优势地位而增加战斗频率的身体需求有关。因此，维氏冕狐猴的高等级地位可能伴随着高昂的代价，然而，这可能被几乎所有父权的垄断所抵消。总之，我们的数据总体上支持了在非狐猴灵长类动物中发现的环境和社会因素与糖皮质激素分泌之间关系的研究结果。
