Aujard F, Perret M
CNRS URA 1183, MNHN, Laboratoire d'Ecologie Générale, Brunoy, France.
Physiol Behav. 1998 Jun 15;64(4):513-9. doi: 10.1016/s0031-9384(98)00087-0.
In the male lesser mouse lemur (Microcebus murinus), a polygamous long-day breeder of which the life span may reach 12-14 years, the effects of aging on socio-sexual relationships were studied on 44 captive animals of various ages. In this primate, new dominance relationships must be established at the beginning of each breeding season. During the breeding season induced by exposure to artificial long days, preoestrous females were introduced into cages of paired males to elicit sexual competition. Sexual behaviors, social interactions through chemical signals, and dominance relationships were recorded in paired males either of similar age (young or aged pairs), or of mixed ages. In all pairs, competition for priority access to females always occurred and dominance relationships were established unrelated to body weight. Although aged animals exhibited significantly less number of sexual and aggressive behaviors, they outranked younger males excepted when reaching oldest age. Independent of male's age, the typical pattern of seasonal rhythm of testosterone was observed, but aged males demonstrated a significant reduction in mean hormonal levels (25.5 +/- 2.8 ng/mL, n = 8) compared to young animals (50 +/- 2.7 ng/mL, n = 8). Moreover, their hormonal response to photoperiod was phase-shifted leading to reduced testosterone values when females entered oestrus. Despite the fact that testosterone levels and sexual behaviors decreased with aging in this primate, older males reached a dominant position, increasing thus their reproductive success.
在雄性小鼠狐猴（Microcebus murinus）中，这种一夫多妻制的长日照繁殖动物寿命可达12 - 14年，对44只不同年龄的圈养动物研究了衰老对社会性行为关系的影响。在这种灵长类动物中，每个繁殖季节开始时都必须建立新的优势关系。在通过暴露于人工长日照诱导的繁殖季节期间，将发情前期的雌性引入成对雄性的笼子中以引发性竞争。记录了年龄相似（年轻或老年对）或年龄混合的成对雄性中的性行为、通过化学信号的社会互动以及优势关系。在所有对中，争夺优先接近雌性的竞争总是会发生，并且优势关系的建立与体重无关。尽管老年动物表现出的性行为和攻击性行为数量明显较少，但除了最老的年龄外，它们比年轻雄性地位更高。与雄性年龄无关，观察到了睾酮季节性节律的典型模式，但与年轻动物（50±2.7 ng/mL，n = 8）相比，老年雄性的平均激素水平显著降低（25.5±2.8 ng/mL，n = 8）。此外，它们对光周期的激素反应发生了相移，导致雌性进入发情期时睾酮值降低。尽管在这种灵长类动物中睾酮水平和性行为会随着衰老而下降，但老年雄性达到了主导地位，从而提高了它们的繁殖成功率。
