Jreidini Nathalie, Green David M
Ecomuseum Zoo, Sainte-Anne-de-Bellevue, Montreal, QC, Canada.
Redpath Museum, McGill University, Montreal, QC, Canada.
Mov Ecol. 2024 May 21;12(1):39. doi: 10.1186/s40462-024-00478-6.
The relationship between animal dispersal and conspecific density has been explored in various study systems but results in terms of both the magnitude and the direction of density dependence are inconsistent. We conducted a thorough review of the literature (2000-2023) and found k = 97 empirical studies of birds, fishes, herpetofauna (amphibians and reptiles), invertebrates, or mammals that had tested for a correlation between conspecific density and animal dispersal. We extracted categorical variables for taxonomic group, sex, age, migratory behavior, study design, dispersal metric, density metric and variable type, as well as temporal and spatial scale, to test each of their correlation with the effect of density on dispersal (Pearson's r) using linear regressions and multilevel mixed-effect modelling. We found certain biases in the published literature, highlighting that the impact of conspecific density on dispersal is not as widespread as it is thought to be. We also found no predominant trend for density-dependent dispersal across taxonomic groups. Instead, results show that the scale and metrics of empirical observations significantly affected analytical results, and heterogeneity measures were high within taxonomic groups. Therefore, the direction and magnitude of the interaction between density and dispersal in empirical studies could partially be attributed to the data collection method involved. We suggest that the contradictory observations for density-dependent dispersal could be explained by dispersal-dependent density, where density is driven by movement instead, and urge researchers to either test this interaction when applicable or consider this perspective when reporting results.
动物扩散与同种密度之间的关系已在各种研究系统中得到探讨，但在密度依赖性的大小和方向方面，结果并不一致。我们对文献（2000 - 2023年）进行了全面回顾，发现有97项关于鸟类、鱼类、爬行类和两栖类动物（两栖动物和爬行动物）、无脊椎动物或哺乳动物的实证研究，测试了同种密度与动物扩散之间的相关性。我们提取了分类群、性别、年龄、迁徙行为、研究设计、扩散指标、密度指标和变量类型等分类变量，以及时间和空间尺度，使用线性回归和多层混合效应模型来测试它们与密度对扩散的影响（皮尔逊r）之间的相关性。我们在已发表的文献中发现了某些偏差，强调同种密度对扩散的影响并不像人们认为的那样广泛。我们还发现，在不同分类群中，密度依赖性扩散没有明显的主导趋势。相反，结果表明，实证观察的尺度和指标显著影响分析结果，并且分类群内部的异质性测量值很高。因此，实证研究中密度与扩散之间相互作用的方向和大小可能部分归因于所涉及的数据收集方法。我们建议，密度依赖性扩散的矛盾观察结果可以用扩散依赖性密度来解释，即密度是由移动驱动的，并敦促研究人员在适用时测试这种相互作用，或者在报告结果时考虑这一观点。
