Department of Anthropology, University of California, Santa Barbara, CA.
Department of Biological Sciences, Purdue University, West Lafayette, IN.
Am J Primatol. 2018 Nov;80(11):e22918. doi: 10.1002/ajp.22918. Epub 2018 Oct 3.
Long-distance vocalizations mediate spacing patterns by allowing groups to choose whether to draw close enough to a neighbor to initiate a short-range interaction. It is unclear, however, whether the patterning of calls and the resulting movements are invariant or change in response to social and ecological variables. In this study, we compare the impact of long-distance calls on neighboring groups' movements in two populations of grey-cheeked mangabeys (Lophocebus albigena) in Uganda, which differed widely in group density and food availability. We monitored movement responses of target groups to both naturally occurring and experimentally simulated "whoop-gobble" vocalizations of neighboring adult males to test whether responses indicated mate and food defense. When defending access to fertile females, males might coerce group members to move away from neighboring males; when defending fitness-limiting food resources, however, groups might approach and attempt to evict neighbors. Controlling for pre-call movement prior to the vocalization, we found no difference in group responses between the low- and high-density populations, and little support for either form of defense. Mangabey groups generally continued moving in their original direction, albeit at a slower pace, and deviations from this pattern were predictable: they avoided nearby callers but approached distant callers; they approached if the caller was in the area where home ranges overlapped; and approached when their own group contained multiple peak-estrous females. The effect of multiple fertile females potentially indicates a breakdown of male control as a result of within-group intrasexual mating competition, and greater-than-expected female control over travel movements. As suspected, grey-cheeked mangabeys use neighbors' long-distance calls to maintain a spatial buffer between groups but changes in group movements indicate a conflict between male and female interests.
远距离叫声通过允许群体选择是否靠近邻居以发起短距离互动，从而调节群体的间隔模式。然而，尚不清楚叫声的模式及其产生的运动是否是不变的，还是会根据社会和生态变量而变化。在这项研究中，我们比较了乌干达两个灰脸山魈（Lophocebus albigena）种群中远距离叫声对邻近群体运动的影响，这两个种群的群体密度和食物可利用性差异很大。我们监测了目标群体对自然发生的和实验模拟的邻近成年雄性“whoop-gobble”叫声的运动反应，以测试这些反应是否表明是为了配偶和食物防御。当为了获得可育雌性而防御时，雄性可能会迫使群体成员远离邻近的雄性；然而，当为了防御限制适应度的食物资源时，群体可能会接近并试图驱逐邻居。在控制叫声前的预先运动后，我们发现低密度和高密度种群之间的群体反应没有差异，也几乎没有支持任何一种防御形式的证据。灰脸山魈群体通常继续朝着原来的方向移动，尽管速度较慢，而且这种模式的偏离是可预测的：它们避开附近的叫声者，但接近远处的叫声者；如果叫声者在与自己的群体重叠的区域内，它们就会接近；当自己的群体中有多个发情高峰期的雌性时，它们也会接近。多个可育雌性的影响可能表明由于群体内的同性交配竞争，雄性控制的崩溃，以及雌性对旅行运动的控制超过预期。正如所料，灰脸山魈利用邻居的远距离叫声来维持群体之间的空间缓冲区，但群体运动的变化表明了雄性和雌性利益之间的冲突。
