The availability and quality of food resources can alter the intensity of competition and predation pressure within communities. Understanding species capacity to respond to global change‐driven shifts in resource distribution is therefore crucial for biodiversity conservation. Small mammal communities are often structured by competition for food resources, but understanding and monitoring these processes are currently hindered by lack of functional dietary trait information in these hard‐to‐sample systems. In this study, we collected a comprehensive suite of gastrointestinal (GI) measurements from 26 small mammal species (including some never reported), compared them with more traditional craniodental traits in predicting dietary guild, and used them in a novel way to understand how diet structures 22 small mammal communities across the Appalachian Mountains of eastern North America. As predicted, we found GI traits to be effective dietary trait proxies; they were equally or more accurate than craniodental proportions in predicting the dietary guild of individual species. Furthermore, at the community level, we found that both the mean and functional dispersion of GI length were positively correlated with latitude and measures of temperature seasonality. Our results indicate that small mammal communities in more seasonal environments are filtered to include species with longer GI tracts (on average) as well as those that can partition food resources more finely, as expected based on the lower productivity of these regions. Conversely, communities in less seasonal environments display functional redundancy from the addition of species with short to intermediate GI lengths. Proportions of the GI tract represent novel dietary traits that can illuminate community assembly processes across regional environmental gradients and in the face of changing timing and availability of resources.

中文翻译：

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胃肠道形态学是一种有效的功能性膳食代理，可预测小型哺乳动物群落结构


食物资源的可用性和质量可以改变社区内部的竞争强度和捕食压力。因此，了解物种应对全球变化驱动的资源分配变化的能力对于生物多样性保护至关重要。小型哺乳动物群落通常是通过对食物资源的竞争构建的，但目前由于这些难以采样的系统中缺乏功能性饮食性状信息，理解和监测这些过程受到阻碍。在这项研究中，我们从 26 种小型哺乳动物物种（包括一些从未报道过）收集了一套全面的胃肠道 （GI） 测量值，将它们与更传统的颅齿特征进行比较以预测饮食公会，并以一种新的方式使用它们来了解饮食如何构建北美东部阿巴拉契亚山脉的 22 个小型哺乳动物群落。正如预测的那样，我们发现 GI 性状是有效的饮食性状代理;在预测单个物种的饮食公会方面，它们与颅齿比例相同或更准确。此外，在群落水平上，我们发现 GI 长度的平均值和功能离散度都与纬度和温度季节性的测量呈正相关。我们的结果表明，根据这些区域的较低生产力，在更具季节性的环境中，小型哺乳动物群落被过滤以包括具有较长 GI 区（平均）的物种以及那些可以更精细地分配食物资源的物种。相反，季节性较弱的环境中的群落由于增加了具有短到中等 GI 长度的物种而显示出功能冗余。 胃肠道的比例代表了新的饮食特征，可以阐明跨区域环境梯度以及面对不断变化的时间和资源可用性的群落组装过程。