Data from: Differences in caste dimorphism among three hornet species (Hymenoptera: Vespidae): forewing size, shape and allometry

Caste shape dimorphism (CShD) has previously been studied in wasps through comparison of different body parts, originating from different imaginal discs. Using geometric morphometrics with a new protocol for measuring wings of pinned specimens from natural history collections, we tested CShD of three hornet species in an organ developed from a single imaginal disc: the forewing. Gaussian Mixture Models retrieved most castes and species levels confirming that caste is an important component of wing variations in females of these hornets. Size and allometry – the influence of size on shape – contribution to wing dimorphism between castes was major, but failed to explain the entire shape dimorphism. This deviation from simple allometric scaling was not similar in the three species: in Vespa tropica, allometric directions in the shape space differed between castes, while in V. crabro and V. velutina they were similar but a significant part of CShD resulted from lateral transpositions. These results clearly indicate that queens are not just enlarged workers. They also support that the different pattern of CShD may result from different developmental mechanism. Finally, they highlight that even in a highly social group like hornets there is still variation in caste dimorphism among species.

品级形状二态性（Caste shape dimorphism, CShD）此前学界已通过对比不同身体部位对胡蜂展开研究，这些身体部位源自不同的成虫盘（imaginal discs）。本研究依托针对自然历史馆藏针插标本翅部测量的全新实验方案，结合几何形态测量学（geometric morphometrics），针对三种胡蜂的前翅——这一由单个成虫盘发育而来的器官——的CShD进行了检验。高斯混合模型（Gaussian Mixture Models）成功实现了绝大多数品级与物种的有效区分，证实品级是这类胡蜂雌性个体翅部形态变异的关键影响因素。尺寸与异速生长（allometry）——即尺寸对形态的调控作用——对不同品级间翅部二态性的贡献占据主导地位，但无法解释全部的形状二态性。这种偏离简单异速生长缩放规律的现象在三个物种中并不一致：热带胡蜂（Vespa tropica）的形态空间异速生长方向在不同品级间存在显著差异，而欧洲胡蜂（Vespa crabro）与黄脚胡蜂（Vespa velutina）的异速生长方向相似，但CShD的显著组分源自横向位移。上述结果明确表明，蜂王并非仅仅是体型放大的工蜂。本研究同时证实，不同的CShD模式可能源于不同的发育机制。最后，研究结果凸显，即便在胡蜂这类高度社会性类群中，不同物种间的品级二态性仍存在显著差异。