Component, group and demographic Allee effects in a cooperatively breeding bird species, the Arabian babbler (Turdoides squamiceps)
Component, group and demographic Allee effects in a cooperatively breeding bird species, the Arabian babbler (Turdoides squamiceps)
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DOI：
10.1007/s00442-016-3656-8
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发表时间：
2016-09-01
期刊：
影响因子：
2.7
通讯作者：
Ridley, Amanda R.
中科院分区：
文献类型：
--
作者：
Keynan, Oded;Ridley, Amanda R.
在种群动力学中，逆密度依赖性可以通过个体适应性特征（分量Allee效应）和种群水平特征（人口统计学Allee效应）来表现。合作繁殖的物种是研究Allee效应相对重要性的一个很好的模型，因为作为一个大群体的一部分，个体会获得不成比例的更大利益。因此，较大的群体比较小的群体有更好的表现，称为群体Allee效应。虽然小人口的合作育种者可能会倾向于所有水平的阿利效应，经验证据的存在，人口阿利效应是稀缺的。为了确定在何种程度上Allee效应存在于合作繁殖的物种，我们使用了一个全面的35年的生活史数据库合作繁殖阿拉伯画眉（Turdoides squamiceps）。首先，我们证实了一个组件Allee效应的存在，表明在大群体中繁殖的个体比在小群体中获得更大的利益;其次，我们证实了群体Allee效应的存在，表明较大的群体生存时间更长。第三，我们发现了人口Allee效应，表明人均人口增长率受到人口密度的积极影响。最后，我们发现，移民和移民率，虽然依赖于组的大小，不缓冲组件和组层面的阿利效应成为人口阿利效应。我们的发现存在的所有三个层次的Allee效应在一个合作的育种者可能有重要的影响，为未来的研究和保护决策。
In population dynamics, inverse density dependence can be manifested by individual fitness traits (component Allee effects), and population-level traits (demographic Allee effects). Cooperatively breeding species are an excellent model for investigating the relative importance of Allee effects, because there is a disproportionately larger benefit to an individual of being part of a large group. As a consequence, larger groups have greater performance than small groups, known as the group Allee effect. Although small populations of cooperative breeders may be prone to all levels of Allee effects, empirical evidence for the existence of a demographic Allee effects is scarce. To determine the extent to which Allee effects are present in a cooperatively breeding species, we used a comprehensive 35-year life history database for cooperatively breeding Arabian babblers (Turdoides squamiceps). Firstly, we confirmed the existence of a component Allee effect by showing that breeding individuals in large groups receive greater benefits than those in small groups; second, we confirmed the existence of group Allee effect by showing that larger groups survive longer. And thirdly, we identified a demographic Allee effect by showing that per capita population growth rate is positively affected by population density. Finally, we found that emigration and immigration rates, although dependent on group size, do not buffer against component and group-level Allee effects becoming a demographic Allee effect. Our finding of the existence of all three levels of Allee effects in a cooperative breeder may have important implications for future research and conservation decisions.