The evolution of feather coloration and song in Old World orioles (genus Oriolus)

What is the tempo and mode of evolution – how fast and in what pattern do traits evolve – is a major question of evolutionary biology. Here we studied patterns of evolutionary change in visual and acoustic signals in Old World orioles. Since producing multiple signals may be costly, we also tested whether there was an evolutionary trade-off between the elaboration of those two types of signals. We studied 30 Oriolus taxa using comparative methods and a recent molecular phylogeny. Morphology and plumage hue evolved comparatively slowly, whereas song evolved rapidly. Among individual feather patches, the evolutionary rate of color was slowest in primaries, which are critical for flapping flight, and fastest in patches exposed to observers (mantle and breast). Thus, primaries seem to be under functional constraint while the evolution of visually exposed patches is perhaps shaped by sexual selection. Song evolution was comparatively fast, but also attracted to a single optimum. This may be ...演化的速率与模式——即性状演化的速度与形式为何——是进化生物学的核心议题之一。本研究聚焦于旧世界黄鹂（Old World orioles）的视觉与声学信号的演化变化模式，鉴于产生多类信号可能存在适应性代价，我们同时检验了这两类信号的精细化演化之间是否存在进化权衡（evolutionary trade-off）。我们采用比较分析方法（comparative methods）与最新的分子系统发育树（molecular phylogeny），对30个黄鹂类群（Oriolus taxa）展开了研究。结果显示，形态与羽色色调的演化速率相对缓慢，而鸣唱的演化则较为迅速。在单个羽毛区域中，初级飞羽（primaries）的颜色演化速率最慢——该结构对振翅飞行至关重要——而暴露于观察者视野的羽毛区域（如背部与胸部）的颜色演化速率最快。由此可见，初级飞羽似乎受到功能约束，而视觉暴露区域的演化或受性选择（sexual selection）塑造。鸣唱的演化速率相对较快，但同时趋向于单一最优表型。这或许是……