Data from: Regulatory mechanisms of group distributions in a gregarious arthropod

In a patchy environment, how social animals manage conspecific and environmental cues in their choice of habitat is a leading issue for understanding their spatial distribution and their exploitation of resources. Here, we experimentally tested the effects of environmental heterogeneities (artificial shelters) and some of their characteristics (size and fragmentation) on the aggregation process of a common species of terrestrial isopod (Crustacea). One hundred individuals were introduced into three different heterogeneous set-ups and in a homogeneous set-up. In the four set-ups, the populations split into two aggregates: one large (approx. 70 individuals) and one smaller (approx. 20 individuals). These aggregates were not randomly distributed in the arena but were formed diametrically opposite from one another. The similarity of the results among the four set-ups shows that under experimental conditions, the environmental heterogeneities have a low impact on the aggregation dynamics and spatial patterns of the isopod, merely serving to increase the probability of nucleation of the larger aggregation at these points. By contrast, the regulation of aggregate sizes and the regular distribution of groups are signatures of local amplification processes, in agreement with the short-range activator and long-range inhibitor model (scale-dependent feedbacks). In other words, we show how small-scale interactions may govern large-scale spatial patterns. This experimental illustration of spatial self-organization is an important step towards comprehension of the complex game of competition among groups in social species.在异质生境中，群居动物在栖息地选择过程中如何整合同种个体与环境的相关线索，是理解其空间分布格局与资源利用策略的核心议题。本研究通过实验，探究了环境异质性（environmental heterogeneities，即人工庇护所（artificial shelters））及其部分特征（尺寸与破碎化程度）对一种常见陆生等足类（terrestrial isopod，甲壳纲）聚集行为过程的影响。我们将100只实验个体分别放置于3种不同的异质实验装置与1种均质实验装置中。在4种实验装置内，实验种群均分裂为两个聚集群：一个规模较大（约70只个体），另一个规模较小（约20只个体）。这两个聚集群并非随机分布于实验容器内，而是彼此呈对角相对的位置形成。4种实验装置所得结果的一致性表明，在本实验条件下，环境异质性对等足类的聚集动力学与空间分布格局的影响较弱，仅能提升大型聚集群在庇护所位点成核的概率。与之相对，聚集群规模的调控与群体的规则分布格局，是局部扩增过程的典型特征，这与短程激活-长程抑制模型（short-range activator and long-range inhibitor model，尺度依赖反馈）的理论预测一致。换言之，本研究证实了小规模个体间的相互作用如何调控大规模空间分布格局的形成。这项针对空间自组织现象的实验阐释，为理解群居物种间群体竞争的复杂博弈过程迈出了重要一步。