Bernstein Irwin S, Weed James L, Judge Peter G, Ruehlmann Thomas E
Department of Psychology, University of Georgia, Athens.
Yerkes Regional Primate Research Center of Emory University, Lawrenceville, Georgia.
Am J Primatol. 1989;18(3):251-257. doi: 10.1002/ajp.1350180309.
Adult male rhesus monkeys lose weight during the breeding season and regain it during the nonbreeding season. The annual pattern of maximum weight gain just prior to the onset of breeding resembles the seasonal "fattening" seen in squirrel monkeys, but the period of weight gain is less discrete. The magnitude of weight change is less in younger males, in that sexually immature males gain weight in both seasons, but significantly less during the breeding season. Females do not lose weight during the breeding season. Post hoc analyses revealed no significant correlations between male testosterone levels, dominance ranks, weights, or weight changes. The heaviest animals as juveniles were predictably the heaviest as adolescents. The timing of seasonal changes in testosterone did not correlate with the timing of changes in weight; weight losses followed the rise in testosterone, and weight gains continued until early in the breeding season after testosterone levels had already begun to rise. It is suggested that seasonal hormonal changes may influence activities in individuals and that changes in the activities of particular group members may alter the activity patterns of other group members. This alteration of activity patterns due to group influences on individuals as well as individual influences on the group may explain why hormonal regulation of seasonal weight appears to be indirect and why individuals (juveniles) experiencing no seasonal hormonal changes nonetheless show differences in activity patterns and seasonal weight changes.
成年雄性恒河猴在繁殖季节体重下降，在非繁殖季节体重回升。繁殖开始前最大体重增加的年度模式类似于松鼠猴的季节性“育肥”，但体重增加的时期不那么明显。年轻雄性的体重变化幅度较小，因为性不成熟的雄性在两个季节都增加体重，但在繁殖季节增加得明显较少。雌性在繁殖季节体重不会下降。事后分析显示，雄性睾酮水平、优势等级、体重或体重变化之间没有显著相关性。幼年时最重的动物在青少年时期也不出所料地最重。睾酮季节性变化的时间与体重变化的时间不相关；体重下降跟随睾酮水平的上升，而体重增加一直持续到繁殖季节早期，此时睾酮水平已经开始上升。有人认为，季节性激素变化可能会影响个体的活动，特定群体成员活动的变化可能会改变其他群体成员的活动模式。由于群体对个体的影响以及个体对群体的影响而导致的活动模式改变，可能解释了为什么季节性体重的激素调节似乎是间接的，以及为什么没有经历季节性激素变化的个体（幼年个体）在活动模式和季节性体重变化方面仍然存在差异。
