Negative density-distribution relationship in butterflies
Negative density-distribution relationship in butterflies
复制标题
蝴蝶的负密度分布关系
作者：
Jussi Päivinen;Alessandro Grapputo;V. Kaitala;A. Komonen;J. Kotiaho;Kimmo Saarinen;Niklas Wahlberg
由于生态学中不存在“自然法则”，社区生态学的许多基础依赖于广泛的统计概括。最强的概括之一是在给定的分类组合中密度和分布之间的正相关关系;也就是说，当地丰富的物种比当地稀疏的物种更广泛。已经提出了几种机制，以创建这种积极的关系，这些机制的测试正在吸引越来越多的attention.ResultsWe报告一个强大的，但违反直觉的，在芬兰的蝴蝶区系的密度和分布之间的负相关关系。凭借异常全面的数据集（数据包括芬兰所有95种常驻物种和超过150万个个体），我们已经能够将其中几种机制提交给强大的直接经验测试。无一例外，我们没有找到证据，提出的机制，创造一个积极的密度分布关系。相反，我们发现，许多的机制是同样能够产生一个负的relationship.ConclusionWe建议，密度分布关系的一个重要的决定因素是研究的地理位置：在边缘的分布范围，合适的栖息地补丁很可能是更孤立的核心范围。在这种情况下，只有最大和质量最好的斑块可能被占用，这些斑块根据定义可以支持相对密集的人口，导致负的密度分布关系。最后，我们得出结论，推广的积极的密度分布关系，应更加谨慎。
BackgroundBecause "laws of nature" do not exist in ecology, much of the foundations of community ecology rely on broad statistical generalisations. One of the strongest generalisations is the positive relationship between density and distribution within a given taxonomic assemblage; that is, locally abundant species are more widespread than locally sparse species. Several mechanisms have been proposed to create this positive relationship, and the testing of these mechanisms is attracting increasing attention.ResultsWe report a strong, but counterintuitive, negative relationship between density and distribution in the butterfly fauna of Finland. With an exceptionally comprehensive data set (data includes all 95 resident species in Finland and over 1.5 million individuals), we have been able to submit several of the mechanisms to powerful direct empirical testing. Without exception, we failed to find evidence for the proposed mechanisms creating a positive density-distribution relationship. On the contrary, we found that many of the mechanisms are equally able to generate a negative relationship.ConclusionWe suggest that one important determinant of density-distribution relationships is the geographical location of the study: on the edge of a distribution range, suitable habitat patches are likely to be more isolated than in the core of the range. In such a situation, only the largest and best quality patches are likely to be occupied, and these by definition can support a relatively dense population leading to a negative density-distribution relationship. Finally, we conclude that generalizations about the positive density-distribution relationship should be made more cautiously.