Chu Xi, Guarraci Fay A, Ågmo Anders
Department of Psychology, University of Tromsø, Norway.
Psychology Department, Southwestern University, USA.
Physiol Behav. 2015 Nov 1;151:46-54. doi: 10.1016/j.physbeh.2015.07.005. Epub 2015 Jul 10.
A promiscuous pattern of copulation has been reported in both wild and domestic rats, and multiple paternity is common. In the present study we determined whether male sociosexual behaviors were associated with reproductive success or not. Groups of rats (3 males and 4 cycling females) were housed in a seminatural environment for a period of 8 days. Sociosexual interactions were observed whenever one or several females were in behavioral estrus. Paternity of the offspring sired was determined by analyses of single nucleotide polymorphisms. Fertility was quantified either as the total number of offspring, or the mean proportion of offspring from all females, sired by the male. Although the total numbers of male social and sexual behaviors during the 8 day period were unrelated to reproductive success, male fertility was correlated with the number of intromissions and ejaculations. In addition intromission and ejaculation ratios (the proportion of mounts ending in intromission and the proportion of the total number of ejaculations received by a female that was contributed by a particular male, respectively) were also correlated with male fertility. Fewer mounts as well as fewer male pursuits of the female were demonstrated by males siring entire litters than by males siring multipaternity litters. Ejaculation order was unrelated to fertility. Male or female preferences (based on various sociosexual interactions) were not strongly related to fertility. Female preference only showed a limited effect. Specifically, preferred males (males who were sniffed most) sired fewer pups. Male dominance status did not affect female preferences, copulatory behavior or fertility. It appears that only behaviors directly related to sperm transfer are important for fertility. Social behaviors in both males and females play a very limited or no role in determining rats' fertility.
在野生和家养大鼠中均有乱交交配模式的报道，多重父权现象很常见。在本研究中，我们确定了雄性社会性行为是否与繁殖成功相关。将几组大鼠（3只雄性和4只处于发情周期的雌性）饲养在半自然环境中8天。每当有一只或几只雌性处于行为发情期时，就观察其社会性行为互动。通过单核苷酸多态性分析来确定所产幼崽的父权。生育力的量化指标要么是后代的总数，要么是雄性使所有雌性受孕所产后代的平均比例。虽然在这8天期间雄性的社会行为和性行为总数与繁殖成功无关，但雄性生育力与插入和射精的次数相关。此外，插入率和射精率（分别指以插入结束的爬跨比例以及特定雄性贡献给雌性的射精总数比例）也与雄性生育力相关。与使整个窝产仔的雄性相比，使多父权窝产仔的雄性表现出更少的爬跨行为以及对雌性更少的追逐行为。射精顺序与生育力无关。雄性或雌性偏好（基于各种社会性行为互动）与生育力没有密切关系。雌性偏好仅显示出有限的影响。具体而言，受偏好的雄性（被嗅闻最多的雄性）产仔较少。雄性的优势地位并不影响雌性偏好、交配行为或生育力。看来只有与精子传递直接相关的行为对生育力才是重要的。雄性和雌性的社会行为在决定大鼠生育力方面所起的作用非常有限或不起作用。
