Island, archipelago and taxon effects: mixed models as a means of dealing with the imperfect design of nature's experiments
Island, archipelago and taxon effects: mixed models as a means of dealing with the imperfect design of nature's experiments
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DOI：
10.1111/j.1600-0587.2011.07078.x
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发表时间：
2012-01-01
期刊：
影响因子：
5.9
通讯作者：
Phillimore, Albert B.
中科院分区：
文献类型：
--
作者：
Bunnefeld, Nils;Phillimore, Albert B.
岛屿地理学的一个主要目的是描述岛屿物种丰富度的一般模式，并确定负责的过程。数据通常是在许多岛屿上收集的;较大的数据集提供了更高的统计能力和更准确的参数估计。然而，观测数据中经常存在结构，这违反了线性模型中每个数据都是独立的假设。在岛屿地理学中，这种结构可能采取岛屿、群岛或由多个数据点表示的分类单元的形式。我们调查最近在这一领域的论文，发现这些形式的非独立性是一个共同的特点。大多数作者通过对每个群岛、分类群或两者的组合进行单独分析来解决这个问题，但是已经存在一种更好的处理数据中的非独立性和结构的工具，即混合模型。我们证明了混合模型方法的优势，将其应用到一个众所周知的数据集，跨越134个观测的单岛地方病（SIE）丰富的39个岛屿，四个群岛和四个类群。考虑到岛屿面积和年龄，SIE丰富度在群岛之间的差异要比在岛屿或类群之间的差异大得多。我们发现，SIE丰富的亚速尔群岛和加拉帕戈斯岛年龄上升，而在加那利群岛和夏威夷SIE丰富最初上升，但后来下降的年龄较大的岛屿。我们的分析表明，应用混合建模方法的岛屿地理学的三个优点：1）数据结构得到控制; 2）岛屿，群岛和分类群之间的方差估计; 3）所有的数据可以包括在一个单一的模型，使其有可能测试是否趋势是一般的所有群岛和分类群或特质。
A major aim of island biogeography has been to describe general patterns of species richness across islands and to identify the processes responsible. Data are often collected across many islands; with larger datasets providing increased statistical power and more accurate parameter estimates. However, there is often structure in observational data, violating an assumption of linear models that each datum is independent. In island biogeography this structure may take the form of an island, archipelago or taxon being represented by multiple data points. We survey recent papers in this field and find that these forms of non-independence are a common feature. Most authors addressed this problem by conducting separate analyses for each archipelago, taxon or combination of the two, but a better tool for dealing with non-independence and structure in data, the mixed model, already exists. We demonstrate the advantages of a mixed model approach by applying it to a well-known dataset that spans 134 observations of single island endemic (SIE) richness across 39 islands, four archipelagos and four taxa. Taking island area and age into account, SIE richness varies substantially more among archipelagos than it does among islands or taxa. We find that SIE richness rises with island age on the Azores and Galapagos, while on the Canaries and Hawaii SIE richness initially rises with age but later declines on older islands. Our analyses demonstrate three advantages to island biogeography of applying a mixed modelling approach: 1) structure in the data is controlled for; 2) the variance among islands, archipelagos and taxa is estimated; 3) all the data can be included in a single model, making it possible to test whether trends are general across all archipelagos and taxa or are idiosyncratic.