Evolution of plumage patterns in pattern morphospace: A phylogenetic analysis of melanerpine woodpeckers

Plumage patterns of melanerpine (Melanerpes-Sphyrapicus) woodpeckers are strikingly diverse. Understanding the evolution and function of this diversity is challenging due to the difficulty of quantifying plumage patterns. We use a 3-dimensional space to characterize the evolution of melanerpine achromatic plumage patterns. The axes of the space are three pattern features (spatial frequency, orientation, and contrast) quantified using 2-dimensional fast Fourier transformation of museum specimen images. Mapping plumage in pattern space reveals differences in how species and subclades occupy the space. To quantify these differences, we derive two new measures of pattern: “pattern diversity” (diversity across plumage patches within a species) and “pattern uniqueness” (divergence of patterns from those of other species). We estimate that the melanerpine ancestor had mottled plumage and find that pattern traits across patches and subclades evolve at different rates. We also find that smaller ..., The photographs were collected with a Nikon D7000 camera and have been converted from .nef file format to .ppm format for use in MATLAB., MATLAB
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暗啄木鸟类（Melanerpes-Sphyrapicus）的羽衣图案多样性极为显著。由于羽衣图案量化难度较高，解析该多样性的演化与功能机制颇具挑战。本研究通过三维空间刻画暗啄木鸟类非彩色羽衣图案的演化历程：该空间的三个维度分别为三类图案特征——空间频率（spatial frequency）、朝向（orientation）与对比度（contrast），均通过对馆藏标本图像开展二维快速傅里叶变换（2-dimensional fast Fourier transformation）量化得到。在图案空间中映射羽衣特征，可揭示不同物种与亚分支在该空间内的分布差异。为量化此类差异，我们提出两项全新的图案量化指标："图案多样性（pattern diversity，即同一物种不同羽区的图案多样性）"与"图案独特性（pattern uniqueness，即该物种图案与其他物种图案的分化程度）"。我们推断暗啄木鸟类的祖先具有斑驳状羽衣，并发现不同羽区与亚分支的图案性状演化速率存在差异。此外我们还发现体型更小的…… 本研究涉及的照片均由尼康D7000（Nikon D7000）相机拍摄，并已从.nef文件格式转换为.ppm格式以适配MATLAB软件。MATLAB R