Methods for shape analysis of landmark data from articulated structures
Methods for shape analysis of landmark data from articulated structures
复制标题
铰接结构地标数据的形状分析方法
DOI：
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发表时间：
1999
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通讯作者：
D. Adams
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作者：
D. Adams
基于地标的几何形态测量方法是研究尺寸和形状的有力工具。这些方法允许使用一组可用于统计假设检验的变量来描述刚性结构的形状，并生成形状差异作为变形的图形表示。然而，当为分析选择的地标跨越多个铰接的刚性结构时，描述一个结构上的地标相对于另一结构上的地标的位置的变化也会出现在数据中。在本文中，我开发了三种新颖的方法来消除铰接结构任意定位的影响。单独子集方法分别为每个地标子集构造形状变量，然后组合结果信息。固定角度方法旋转标志的一个子集，使得子集之间的角度在样本之间保持不变，然后将它们视为形状分析的刚性结构。正交投影方法估计由于关节运动的影响而产生的失真，用向量对其进行近似，然后在统计分析之前从形状数据中删除该维度。我详细描述了每种方法，并演示了它们在包含来自多个三刺刺鱼（Gasterosteus aculeatus）种群的头骨和下颌标志的数据集上的使用。使用所有方法的结果与以前的发现以及相互之间进行比较，并讨论了对功能形态学研究的影响。
Landmark-based geometric morphometric methods are powerful tools in the study of size and shape. These methods allow one to describe the shape of rigid structures using a set of variables that can be used for statistical hypothesis testing, and to generate graphical representations of shape differences as deformations. However, when the landmarks chosen for an analysis span multiple rigid structures that articulate, variation describing the position of landmarks on one structure relative to those on another is also present in the data. In this paper, I develop three novel methods to remove the effects of arbitrary positioning of articulated structures. The separate subset method constructs shape variables for each subset of landmarks separately, then combines the resulting information. The fixed angle method rotates one subset of landmarks so the angle between subsets is invariant among specimens, and then treats them as a rigid structure for the shape analyses. The orthogonal projection method estimates the distortion due to the effects of articulation motion, approximates it with a vector, and then removes this dimension from the shape data before statistical analysis. I describe each of these methods in detail, and demonstrate their use on a data set containing landmarks from skulls and lower jaws from several populations of the threespine stickleback, Gasterosteus aculeatus. The results using all methods are compared to previous findings and to each other, and the implications for studies of functional morphology are discussed.