Data from: Quantifying water requirements of African ungulates through a combination of functional traits

Climate and land use change modify surface water availability in African savannas. Surface water is a key resource for both wildlife and livestock and its spatial and temporal distribution is important for understanding the composition of large herbivore assemblages in savannas. Yet, the extent to which ungulate species differ in their water requirements remains poorly quantified. Here, we infer the water requirements of 48 African ungulates by combining six different functional traits related to physiological adaptations to reduce water loss, namely minimum dung moisture, relative dung pellet size, relative surface area of the distal colon, urine osmolality, relative medullary thickness and evaporation rate. In addition, we investigated how these differences in water requirements relate to differences in dietary water intake. We observed strong correlations between traits related to water loss through dung, urine and evaporation, suggesting that ungulates minimize water loss through multiple pathways simultaneously, which suggests that each trait can thus be used independently to predict water requirements. Furthermore, we found that browsers and grazers had similar water requirements, but browsers are expected to be less dependent on surface water because they acquire more water through their diet. We conclude that these key functional traits are a useful way to determine differences in water requirements and an important tool for predicting changes in herbivore community assembly resulting from changes in surface water availability.气候变化与土地利用变化会改变非洲稀树草原的地表水资源可获得性。地表水资源是野生动物与家畜的关键生存资源，其空间与时间分布对于解析稀树草原大型植食动物群落的组成结构至关重要。然而，不同有蹄类动物（ungulate）的需水量差异程度仍未得到充分量化。本研究结合六项与减少水分流失的生理适应相关的功能性状，估算了48种非洲有蹄类动物的需水量，这些性状分别为：最低粪便含水量、粪便颗粒相对尺寸、远端结肠相对表面积、尿渗透压、肾髓质相对厚度以及蒸发速率。此外，本研究还探讨了需水量差异与膳食水分摄入差异之间的关联。本研究观察到，与粪便、尿液及蒸发途径水分流失相关的性状之间存在显著相关性，这表明有蹄类动物会同时通过多种途径减少水分流失，也意味着每项性状均可独立用于预测需水量。此外，本研究发现木本植食者（browser）与草本植食者（grazer）的需水量相近，但木本植食者因可从膳食中获取更多水分，其对地表水资源的依赖程度更低。本研究最终得出结论：这些关键功能性状可有效区分不同物种的需水量差异，同时也是预测地表水资源变化引发的植食动物群落组成变化的重要工具。