SOCIAL STIMULATION AND SEXUAL DEVELOPMENT

社会环境中的因素，如心理社会刺激和 来自与同种生物相互作用的压力，可能会影响 性成熟。一个物种的社会性程度可能会影响 女性对社会信号的反应或通过什么机制 社会暗示会影响生殖。这项研究的长期目标是 程序的目的是检查影响时间的机制 繁殖。了解社交线索的性质，可能 影响生殖和性发育是揭示 生理和神经机制，以及进化基础， 哺乳动物的生殖时间。这些目标有三个具体目标 实验：(1)确定社交线索是否能抑制或 在两种不同程度的啮齿动物中延迟生殖 社会性，(2)如果两个物种的雌性都表现出生殖能力 抑制，然后检查参与中介抑制的线索 以及(3)在自然条件下检验抑制线索的效果。 在这些实验中将对两种啮齿动物进行比较：松鼠， 合作的饲养员，以及倾向于不太合群的草地田鼠 在繁殖季节。在许多合作繁殖的物种中， 通常只有一只雌性生殖，尽管是非生殖群体 会员还为青少年提供照顾。延迟繁殖也一直是 在非合作繁殖的雌性中报告，至少在 人口密度高。缺乏或延迟生殖似乎是极其严重的 由于直接健身能力的丧失，个体付出了高昂的代价(Brown，1987)。 初步实验(实验1和实验2)将确定抑制的来源 更年轻的女性。化学药物与非化学药物的相对有效性 将考察抑制生殖的行为线索(实验1和 2)。与潜在伴侣的接触量和 将检查抑制线索，以确定 抑制生殖与缺乏与男性的充分接触 作为对野外压制的一种解释(实验3)。最后， 将确定需要呈现化学提示的频率 在自然环境中进行测试之前(实验4)。如果抑制 在实验室、田野里，生殖是对化学信号的反应 将进行实验以评估化学线索的有效性 关于半自然环境下的生殖(Exp 5和Exp 6)。繁育的雌性 会被移除，然后提供化学线索来确定化学物质 在野外条件下，仅有线索就能抑制繁殖。最后，一个 使用化学线索的类似研究将在果园环境中进行 松鼠(实验7)。这些实验的结果将提供 对相关机制和选择压力的有价值的见解 用于哺乳动物延迟繁殖的进化和/或维持 社会性程度不同的物种。

Factors in the social environment, such as psychosocial stimulation and stress from interactions with conspecifics, may influence the timing of sexual maturation. The degree of sociality of a species may affect the responsiveness of females to social signals or the mechanism by which social cues influence reproduction. The long-term goal of this research program is to examine the mechanisms that affect the timing of reproduction. Understanding the nature of the social cues that may influence reproduction and sexual development is central to uncovering the physiological and neural mechanisms, as well as the evolutionary basis, of reproductive timing in mammals. There are three specific goals of these experiments: (1) to determine whether or not social cues can suppress or delay reproduction in two species of rodents that differ in the degree of sociality, (2) if females in both species exhibit reproductive suppression, then to examine the cues involved in mediating suppression and, (3) to test the effects of suppressive cues under natural conditions. Two rodent species will be compared in these experiments: the pine vole, a cooperative breeder, and the meadow vole, which tends to be less social during the breeding season. In a number of cooperatively breeding species, only one female typically reproduces although non-reproductive group members also provide care to young. Delayed reproduction has also been reported in noncooperatively breeding females, at least during periods of high population density. Lack of or delayed reproduction seems extremely costly to individuals due to losses in direct fitness (Brown 1987). Initial experiments (Exp 1 and 2) will determine the source of suppression of younger females. The relative effectiveness of chemical versus behavioral cues in suppression of reproduction will be examined (Exp 1 and 2). Variations in the amount of contact with a potential mate and suppressive cues will be examined to determine the likelihood of suppression of reproduction versus lack of sufficient contact with males as an explanation of suppression in the wild (Exp 3). Finally, the frequency with which chemical cues need to be presented will be determined prior to tests in a natural setting (Exp 4). If suppression of reproduction occurs in response to chemical cues in the laboratory, field experiments will be conducted to assess the effectiveness of chemical cues on reproduction in semi-natural settings (Exp 5 and 6). Breeding females will be removed and then chemical cues presented to determine if chemical cues alone can suppress reproduction in a field situation. Finally, a similar study using chemical cues will be conducted in an orchard setting with pine voles (Exp 7). The results of these experiments will provide valuable insights into the mechanisms and selection pressures responsible for the evolution and/or maintenance of delayed reproduction in mammalian species that differ in the degree of sociality.