What explains vast differences in jumping power within a clade? diversity, ecology, and evolution of anuran jumping power

1. Anuran (frog and toad) jumping power varies greatly across species, yet muscle power does not. Given that the jumping power of some species is up to five times higher than typical muscle power, power amplification by elastic elements is suggested to explain this discrepancy. However, the ecological reasons for this variation in jumping power are unclear. One hypothesis is that small jumpers are limited by the time available to accelerate their body during take-off, leading to small species needing greater power production than larger species to achieve similar jumping performance. Another (non-mutually exclusive) hypothesis is that the microhabitat species inhabit may drive variation through trade-offs with performance in microhabitat-specific, non-jumping behaviors. 2. We compared jumping power across 68 anuran species that were diverse in evolutionary relationships, microhabitat use, and body mass. We used phylogenetic comparative methods to compare the role of microhabitat and body mass in explaining variation in jumping power across species. 3. We found the strongest support for a model that included two factors and their interaction. First, as body mass increased, jumping power decreased. Second, species that burrowed showed lower jumping power than species that did not burrow. Third, the interaction between body mass and burrowing behavior showed that jumping power declines more rapidly with body mass in burrowing species than non-burrowing species. 4. The effect of body mass suggests that interspecific variation in jumping power might be partly explained by scaling relationships. Anurans with small body mass may be able to achieve similar locomotor performance (e.g. takeoff velocity) as those with larger body mass, by more effectively amplifying muscle power. Additionally, the effect of burrowing behavior suggests that species that use hindlimbs to burrow may experience a reduction in their ability to generate jumping power. This may indicate a functional trade-off between jumping and burrowing performance.

1. 无尾目（Anuran，包含蛙类与蟾蜍类）物种的跳跃功率在不同物种间差异显著，但其肌肉功率却无明显变化。鉴于部分物种的跳跃功率可达典型肌肉功率的五倍以上，学界提出通过弹性元件实现功率放大来解释这一矛盾现象。但目前学界对造成跳跃功率物种间差异的生态动因仍不甚明晰。其中一种假说指出，小型跳跃类群在起飞阶段用于加速身体的时间受限，因此小型物种需比大型物种产生更高的功率，才能达到相近的跳跃表现。另一种（非互斥的）假说则认为，物种所栖息的微生境，可通过与微生境特异性非跳跃行为的性能权衡，驱动跳跃功率的物种间差异。2. 本研究针对68种演化关系、微生境利用策略与体重均存在显著差异的无尾目物种，对比了它们的跳跃功率。我们采用系统发育比较方法（phylogenetic comparative methods），分析了微生境与体重在解释物种间跳跃功率差异中的作用。3. 本研究结果最支持包含两个因子及其交互作用的模型。其一，体重越大，跳跃功率越低；其二，穴居物种的跳跃功率显著低于非穴居物种；其三，体重与穴居行为的交互作用表明，穴居物种的跳跃功率随体重增加的下降速率快于非穴居物种。4. 体重的影响效应提示，跳跃功率的种间变异或许可部分通过标度关系（scaling relationships）解释。体重较小的无尾目物种，可通过更高效地放大肌肉功率，达到与大体型物种相近的运动表现（如起飞速度（takeoff velocity））。此外，穴居行为的影响效应表明，依赖后肢掘穴的物种，其产生跳跃功率的能力可能有所下降，这或许暗示了跳跃性能与掘穴性能之间存在功能权衡（functional trade-off）。