Mattle Franziska M E, Pryce Christopher R, Anzenberger Gustl
Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
Horm Behav. 2008 Aug;54(2):302-11. doi: 10.1016/j.yhbeh.2008.03.004. Epub 2008 Mar 25.
Callitrichids are cooperative breeders, characterized by obligate twinning, extensive paternal care, and monopolization of reproduction by the dominant female. This is the case in the common marmoset, and in common marmoset groups of more than one adult female, subordinate females are typically acyclic consistent with infertility. However, one callitrichid, Goeldi's monkey, gives birth to singletons and exhibits low paternal care. Given these reproductive traits of Goeldi's monkey, we hypothesized that there would not be suppression of ovarian activity. To test this hypothesis, we applied non-invasive endocrine methods in a step-wise experiment with laboratory groups of both species. In each species, six pairs of sisters were studied alone, in visual contact with an unrelated male and in a polygynous trio with the male, and urine samples were collected for determination of oestrogen titres reflecting ovarian activity. Common marmoset sister pairs exhibited a marked difference in social status: during the study 5 of 6 dominant females conceived but only 1 of 6 subordinate females; the remaining 5 subordinates were acyclic at the end of the study, and instances of ovulation typically resulted in aggression. Goeldi's monkey sister pairs showed no status differences: in all pairs, however, both sisters exhibited a temporary cessation of ovarian cyclicity on trio formation, followed by ovulation and conception. We conclude that these marked differences in ovarian responses reflect the differences in inter-female competition for paternal caregiving resources. In common marmosets with high inter-female competition, suppression of ovulation functions to reduce aggression received by subordinate females; in Goeldi's monkey with low competition, temporary cessation of ovulation could facilitate female choice.
绢毛猴是合作繁殖者，其特征为必然孪生、广泛的父性照料以及占主导地位的雌性对繁殖的垄断。普通狨猴就是如此，在有不止一只成年雌性的普通狨猴群体中，从属雌性通常处于无发情周期状态，与不孕相符。然而，有一种绢毛猴，即白喉卷尾猴，产单胎且父性照料较少。鉴于白喉卷尾猴的这些繁殖特征，我们推测其卵巢活动不会受到抑制。为验证这一假设，我们在一个逐步实验中对两个物种的实验室群体应用了非侵入性内分泌方法。在每个物种中，研究了六对姐妹，先是单独研究，然后是与一只无亲缘关系的雄性处于视觉接触状态，最后是与该雄性组成一夫多妻制三人组，并且收集尿液样本以测定反映卵巢活动的雌激素水平。普通狨猴姐妹对在社会地位上表现出显著差异：在研究期间，6只占主导地位的雌性中有5只受孕，但6只从属雌性中只有1只受孕；其余5只从属雌性在研究结束时处于无发情周期状态，而且排卵情况通常会引发攻击行为。白喉卷尾猴姐妹对没有地位差异：在所有配对中，然而，两只姐妹在三人组形成时都表现出卵巢周期性的暂时停止，随后排卵并受孕。我们得出结论，这些卵巢反应的显著差异反映了雌性之间在争夺父性照料资源方面的差异。在雌性间竞争激烈的普通狨猴中，排卵抑制起到减少从属雌性所受攻击的作用；在竞争较弱的白喉卷尾猴中，排卵的暂时停止可能有助于雌性做出选择。
