Conradt L, Roper T J
Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Proc Biol Sci. 2000 Nov 7;267(1458):2213-8. doi: 10.1098/rspb.2000.1271.
A social group can only be spatially coherent if its members synchronize activities such as foraging and resting. However, activity synchronization is costly to individuals if it requires them to postpone an activity that would be personally more profitable in order to do what the rest of the group is doing. Such costs will be particularly high in groups whose members belong to different age, size or sex classes since the optimal allocation of time to various activities is likely to differ between such classes. Thus, differences in the costs of activity synchronization between and within classes could cause non-homogenous groups to be less stable than homogenous groups, with the result that homogenous groups predominate in the population: that is, they could cause 'social segregation' of animals of different sex, size or age. We develop a model that predicts the degree of social segregation attributable to differences in activity synchronization between homogenous and non-homogenous groups and use this model in determining whether activity synchronization can explain intersexual social segregation in red deer (Cervus elaphus). Differences in activity synchronization between mixed-sex and unisex groups of red deer explained 35% of the observed degree of intersexual social segregation, showing that activity synchronization is an important cause of social segregation in this species.
一个社会群体只有在其成员同步诸如觅食和休息等活动时，才可能在空间上保持连贯。然而，如果活动同步要求个体推迟一项对其个人而言更有利可图的活动，而去做群体中其他成员正在做的事情，那么这对个体来说成本是很高的。在其成员属于不同年龄、体型或性别类别的群体中，这种成本会特别高，因为不同类别之间在各种活动上的最佳时间分配可能会有所不同。因此，不同类别之间以及同一类别内部活动同步成本的差异，可能会导致非同质群体比同质群体更不稳定，结果是同质群体在种群中占主导地位：也就是说，它们可能会导致不同性别、体型或年龄的动物出现“社会隔离”。我们建立了一个模型，该模型预测由于同质群体和非同质群体之间活动同步差异导致的社会隔离程度，并使用这个模型来确定活动同步是否能够解释马鹿（Cervus elaphus）的两性间社会隔离现象。马鹿的混合性别群体和单性别群体之间的活动同步差异，解释了所观察到的两性间社会隔离程度的35%，这表明活动同步是该物种社会隔离的一个重要原因。
