Cost of dispersal in a social mammal: body mass loss and increased stress

Dispersal is a key process influencing the dynamics of socially and spatially structured populations. Dispersal success is determined by the state of individuals at emigration and the costs incurred after emigration. However, quantification of such costs is often difficult, due to logistical constraints of following wide-ranging individuals. We investigated the effects of dispersal on individual body mass and stress hormone levels in a cooperative breeder, the meerkat (Suricata suricatta). We measured body mass and faecal glucocorticoid metabolite (fGCM) concentrations from 95 dispersing females in 65 coalitions through the entire dispersal process. Females that successfully settled lost body mass, while females that did not settle but returned to their natal group after a short period of time did not. Furthermore, dispersing females had higher fGCM levels than resident females, and this was especially pronounced during the later stages of dispersal. By adding information on the transie...扩散（dispersal）是影响社会结构与空间结构种群动态的关键过程。扩散成功率取决于个体迁出时的状态以及迁出后产生的代价。然而，由于追踪活动范围广泛的个体存在后勤制约，对这类代价的量化往往颇具难度。本研究以合作繁育物种（cooperative breeder）狐獴（Suricata suricatta）为研究对象，探究了扩散对个体体重与应激激素水平的影响。研究人员在整个扩散过程中，对65个扩散联盟中的95只扩散雌性个体的体重与粪便糖皮质激素代谢物（faecal glucocorticoid metabolite, fGCM）浓度进行了测定。成功定居的雌性个体出现体重下降，而未成功定居、仅短暂离开后便返回出生群（natal group）的雌性个体则无此类变化。此外，扩散雌性个体的fGCM水平高于定居雌性个体，且该差异在扩散后期尤为显著。本研究通过补充有关暂[原文未完整呈现后续内容]