The extinction of megafauna may lead to the trophic collapse of ecosystems that depend on the dung that they produce. Some dung beetle species may undergo phenotypic changes in response to altered resource availability. The pronotal width of dung beetles is a trait that can be used as a proxy measure for the amount of dung provisioned during the larval stage. In this study conducted in Peninsular Malaysia, we compare the intraspecific difference in pronotal widths of dung beetles in forests with and without megafauna. Beetles were collected using burrowing interception traps baited with elephant dung. Six species with a minimum sample size of 55 beetles per species were used. Pronotum widths were compared using Bayesian estimation (BEST). There was no credible difference between intraspecific pronotal widths of four species, but credible differences between the mean parameters of two species, Liatongus femoratus and Oniticellus tessellatus. Both these species belong to genera that have a close association with megafauna, while the other are believed to be generalists. This may indicate that species that depend on megafauna dung as a breeding resource undergo a phenotypic change following the loss of their preferred dung type. Phenotypic changes appear to be a pathway which allows species to survive the initial trophic collapse of an ecosystem.

中文翻译：

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马来西亚半岛蜣螂（Scarabaeidae：Scarabaeinae）对大型动物粪便损失的特征反应

巨型动物的灭绝可能导致依赖它们产生的粪便的生态系统的营养崩溃。一些蜣螂物种可能会因资源可用性的改变而发生表型变化。蜣螂的前体宽度是一个性状，可用作幼虫阶段提供的粪便量的替代指标。在这项在马来西亚半岛进行的研究中，我们比较了有和没有巨型动物的森林中蜣螂的前叶宽度的种内差异。使用以大象粪便为诱饵的挖洞拦截陷阱收集甲虫。使用了六个物种，每个物种的最小样本量为 55 只甲虫。使用贝叶斯估计 (BEST) 比较前背板宽度。四个物种的种内前胸宽度之间没有可信的差异，股肋骨和缟丝藻. 这两个物种都属于与巨型动物密切相关的属，而另一个被认为是通才。这可能表明依赖大型动物粪便作为繁殖资源的物种在失去其首选的粪便类型后会发生表型变化。表型变化似乎是让物种在生态系统最初的营养崩溃中幸存下来的途径。