Data from: Wing shape variation associated with mimicry in butterflies

Mimetic resemblance in unpalatable butterflies has been studied by evolutionary biologists for over a century, but has largely focused on the convergence in wing color patterns. In Heliconius numata, discrete color-pattern morphs closely resemble co-mimics in the distantly-related genus Melinaea. We examine the possibility that the shape of the butterfly wing also shows adaptive convergence. First, simple measures of forewing dimensions were taken of individuals in a cross between H. numata morphs, and showed quantitative differences between two of the segregating morphs, F. elegans and F. silvana. Second, landmark-based geometric morphometric and elliptical Fourier outline analyses were used to more fully characterize these shape differences. Extension of these techniques to specimens from natural populations suggested that, while many of the coexisting morphs could not be discriminated by shape, the differences we identified between F. elegans and F. silvana hold in the wild. Interestingly, despite extensive overlap, the shape variation between these two morphs is paralleled in their respective Melinaea co-mimics. Our study therefore suggests that wing-shape variation is associated with mimetic resemblance, and raises the intriguing possibility that the supergene responsible for controlling the major switch in color pattern between morphs also contributes to wing shape differences in H. numata.

百余年来，进化生物学家一直在研究不可食蝴蝶的拟态相似性，但既往研究大多聚焦于翅色图案的趋同演化。在努玛釉蛱蝶（Heliconius numata）中，其离散的翅色图案变型与远缘的美蜓蛱蝶属（Melinaea）物种高度相似。本研究旨在探讨蝴蝶翅形是否同样存在适应性趋同演化的可能。首先，我们对努玛釉蛱蝶不同变型杂交后代的前翅尺寸进行了简单测量，发现两个分离变型——优雅变型（F. elegans）与锡尔瓦纳变型（F. silvana）——之间存在量化差异。其次，我们采用基于标志点的几何形态测量法与椭圆傅里叶轮廓分析法，对这些翅形差异进行了更全面的表征。将这些技术拓展应用于自然种群的标本后发现，尽管多数共存变型无法通过翅形加以区分，但我们在优雅变型与锡尔瓦纳变型间鉴定出的差异在野生种群中同样存在。有趣的是，尽管二者翅形存在广泛重叠，但这两个变型间的翅形变异模式，与其各自对应的美蜓蛱蝶属共拟态物种的翅形变异模式一致。因此，本研究表明翅形变异与拟态相似性存在关联，并提出了一个引人关注的可能性：控制不同变型间翅色图案主要转换的超基因（supergene），同样对努玛釉蛱蝶的翅形差异具有调控作用。