Data from: Selection for mechanical advantage underlies multiple cranial optima in new world leaf-nosed bats

Selection for divergent performance optima has been proposed as a central mechanism underlying adaptive radiation. Uncovering multiple optima requires identifying forms associated with different adaptive zones and linking those forms to performance. However, testing and modeling the performance of complex morphologies like the cranium is challenging. We introduce a three-dimensional finite element (FE) model of the cranium that can be morphed into different shapes by varying simple parameters to investigate the relationship between two engineering-based measures of performance, mechanical advantage and von Mises stress, and four divergent adaptive zones occupied by New World leaf-nosed bats. To investigate these relationships,we tested the fit of Brownian motion and Ornstein-Uhlenbeck models of evolution in mechanical advantage and von Mises stress using dated multi-locus phylogenies. The analyses revealed three performance optima for mechanical advantage among species from three adaptive zones: bats that eat nectar; generalized insectivores omnivores and some frugivores; and bats that specialize on hard canopy fruits. Only two optima, one corresponding to nectar feeding, were consistently uncovered for von Mises stress. These results suggest that mechanical advantage played a larger role than von Mises stress in the radiation of New World leaf-nosed bats into divergent adaptive zones.

针对分化性能最适值的选择，被认为是适应性辐射背后的核心机制。要揭示多重性能最适值，需先鉴别与不同适应性生态位相关的形态特征，并将这些形态与性能表现建立关联。然而，对颅骨这类复杂形态的性能开展测试与建模，仍颇具挑战。本研究构建了一款三维有限元（finite element, FE）颅骨模型，可通过调整简单参数实现形态变形，以此探究两项基于工程学的性能指标——机械优势（mechanical advantage）与冯·米塞斯应力（von Mises stress）——与新大陆叶口蝠占据的四类分化适应性生态位之间的关联。为探究上述关联，本研究利用带有时间校准的多位点系统发育树，测试了布朗运动（Brownian motion）与奥恩斯坦-乌伦贝克（Ornstein-Uhlenbeck）两种进化模型在机械优势和冯·米塞斯应力上的拟合优度。分析结果显示，来自三类适应性生态位的物种在机械优势上存在三类性能最适值：取食花蜜的蝙蝠；广谱食虫性、杂食性以及部分果食性蝙蝠；以及特化取食硬质树冠层果实的蝙蝠。而针对冯·米塞斯应力，仅能稳定检测到两类性能最适值，其中一类对应花蜜取食生态位。上述结果表明，在新大陆叶口蝠向分化适应性生态位辐射演化的过程中，机械优势所发挥的作用要大于冯·米塞斯应力。