Data from: Go big or go fish: morphological specializations in carnivorous bats

Specialized carnivory is relatively uncommon across mammals, and bats constitute one of the few groups in which this diet has evolved multiple times. While size and morphological adaptations for carnivory have been identified in other taxa, it is unclear what phenotypic traits characterize the relatively recent evolution of carnivory in bats. To address this gap, we apply geometric morphometric and phylogenetic comparative analyses to elucidate which characters are associated with ecological divergence of carnivorous bats from insectivorous ancestors, and if there is morphological convergence among independent origins of carnivory within bats, and with other carnivorous mammals.We find that carnivorous bats are larger and converged to occupy a subset of the insectivorous morphospace, characterized by skull shapes that enhance bite force at relatively wide gapes. Piscivorous bats are morphologically distinct, with cranial shapes that enable high bite force at narrow gapes, which is necessary for processing fish prey. All animal-eating species exhibit positive allometry in rostrum elongation with respect to skull size, which could allow larger bats to take relatively larger prey. The skull shapes of carnivorous bats share similarities with generalized carnivorans, but tend to be more suited for increased bite force production at the expense of gape, when compared with specialized carnivorans.

在哺乳动物类群中，特化肉食性（specialized carnivory）相对罕见，而蝙蝠是此类食性多次独立演化的少数类群之一。尽管其他类群中已发现针对肉食性的体型与形态适应性特征，但目前仍不清楚蝙蝠中相对近期演化出的肉食性所对应的表型特征。为填补这一研究空白，我们采用几何形态测量学（geometric morphometric）与系统发育比较分析（phylogenetic comparative analyses），旨在阐明肉食性蝙蝠从食虫祖先分化的生态趋异相关特征，并验证蝙蝠内部独立起源的肉食性类群之间，以及它们与其他肉食性哺乳动物之间是否存在形态趋同。研究结果显示，肉食性蝙蝠体型更大，且在形态空间上收敛于食虫类群的一个子集，其颅骨形态可在相对较宽的口裂下提升咬合力。食鱼蝙蝠（piscivorous bats）的形态特征独具一格，其颅骨形态能够在狭窄口裂下产生高咬合力，这是处理鱼类猎物所必需的。所有以动物为食的蝙蝠类群均表现出吻突（rostrum）伸长相对于颅骨尺寸的正异速生长（positive allometry），这一特征可使体型更大的蝙蝠捕食相对更大的猎物。与广义食肉目动物相比，肉食性蝙蝠的颅骨形态存在相似之处，但相较于特化食肉目动物，其颅骨形态更适配更高的咬合力，而代价则是口裂宽度的缩减。