Stephens P A, Russell A F, Young A J, Sutherland W J, Clutton-Brock T H
Department of Zoology and Physiology, University of Wyoming, P.O. Box 3166, Laramie, Wyoming 82071, USA.
Am Nat. 2005 Jan;165(1):120-35. doi: 10.1086/426597. Epub 2004 Nov 22.
Decisions regarding immigration and emigration are crucial to understanding group dynamics in social animals, but dispersal is rarely treated in models of optimal behavior. We developed a model of evolutionarily stable dispersal and eviction strategies for a cooperative mammal, the meerkat Suricata suricatta. Using rank and group size as state variables, we determined state-specific probabilities that subordinate females would disperse and contrasted these with probabilities of eviction by the dominant female, based on the long-term fitness consequences of these behaviors but incorporating the potential for error. We examined whether long-term fitness considerations explain group size regulation in meerkats; whether long-term fitness considerations can lead to conflict between dominant and subordinate female group members; and under what circumstances those conflicts were likely to lead to stability, dispersal, or eviction. Our results indicated that long-term fitness considerations can explain group size regulation in meerkats. Group size distributions expected from predicted dispersal and eviction strategies matched empirical distributions most closely when emigrant survival was approximately that determined from the field study. Long-term fitness considerations may lead to conflicts between dominant and subordinate female meerkats, and eviction is the most likely result of these conflicts. Our model is computationally intensive but provides a general framework for incorporating future changes in the size of multimember cooperative breeding groups.
关于迁入和迁出的决策对于理解群居动物的群体动态至关重要，但在最优行为模型中，扩散很少被考虑。我们为一种群居哺乳动物狐獴（Suricata suricatta）建立了一个进化稳定的扩散和驱逐策略模型。以等级和群体规模作为状态变量，我们确定了从属雌性扩散的特定状态概率，并将其与占主导地位的雌性驱逐的概率进行对比，这基于这些行为的长期适应性后果，但纳入了出错的可能性。我们研究了长期适应性考量是否能解释狐獴群体规模的调节；长期适应性考量是否会导致占主导地位和从属的雌性群体成员之间的冲突；以及在何种情况下这些冲突可能导致群体稳定、扩散或驱逐。我们的结果表明，长期适应性考量可以解释狐獴群体规模的调节。当迁出者的存活率约为实地研究确定的存活率时，根据预测的扩散和驱逐策略预期的群体规模分布与经验分布最为匹配。长期适应性考量可能会导致占主导地位和从属的雌性狐獴之间的冲突，而驱逐是这些冲突最可能的结果。我们的模型计算量很大，但为纳入未来多成员合作繁殖群体规模的变化提供了一个通用框架。
