Larger species tend to feed on abundant resources, which nonetheless have lower quality or degradability, the so‐called Jarman‐Bell principle. The “eat more” hypothesis posits that larger animals compensate for lower quality diets through higher consumption rates. If so, evolutionary shifts in metabolic scaling should affect the scope for this compensation, but whether this has happened is unknown. Here, we investigated this issue using termites, major tropical detritivores that feed along a humification gradient ranging from dead plant tissue to mineral soil. Metabolic scaling is shallower in termites with pounding mandibles adapted to soil‐like substrates than in termites with grinding mandibles adapted to fibrous plant tissue. Accordingly, we predicted that only larger species of the former group should have more humified, lower quality diets, given their higher scope to compensate for such a diet. Using literature data on 65 termite species, we show that diet humification does increase with body size in termites with pounding mandibles, but is weakly related to size in termites with grinding mandibles. Our findings suggest that evolution of metabolic scaling may shape the strength of the Jarman‐Bell principle.

中文翻译：

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代谢规模的变化可以预测饮食质量和体型之间的共同进化吗？

较大的物种往往以丰富的资源为食，但这些资源的质量或降解性较低，即所谓的 Jarman-Bell 原理。“多吃”假设假设较大的动物通过较高的消费率来补偿较低质量的饮食。如果是这样，代谢规模的进化变化应该会影响这种补偿的范围，但这是否发生了未知。在这里，我们使用白蚁研究了这个问题，白蚁是主要的热带食腐动物，它们沿着从死亡植物组织到矿质土壤的腐殖化梯度进食。与下颚磨碎适应纤维植物组织的白蚁相比，下颌骨适应土壤基质的白蚁的代谢结垢更浅。因此，我们预测只有前一组中较大的物种应该有更多腐殖质、质量较低的饮食，鉴于他们有更大的空间来补偿这种饮食。使用关于 65 种白蚁的文献数据，我们表明饮食腐殖化确实随着下颚撞击的白蚁的体型增加而增加，但与下颚磨碎的白蚁的大小相关性较弱。我们的研究结果表明，代谢标度的演变可能会影响 Jarman-Bell 原理的强度。