School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA, 99164-2812, USA.
Department of Rangeland, Wildlife and Fisheries Management, Texas A&M University, College Station, TX, 77843, USA.
Sci Rep. 2022 Sep 9;12(1):15251. doi: 10.1038/s41598-022-19742-z.
The eight species of bears world-wide consume a wide variety of diets. Some are specialists with extensive anatomical and physiological adaptations necessary to exploit specific foods or environments [e.g., polar bears (Ursus maritimus), giant pandas (Ailuropoda melanoleuca), and sloth bears (Melursus ursinus)], while the rest are generalists. Even though ursids evolved from a high-protein carnivore, we hypothesized that all have become low-protein macronutrient omnivores. While this dietary strategy has already been described for polar bears and brown bears (Ursus arctos), a recent study on giant pandas suggested their macronutrient selection was that of the ancestral high-protein carnivore. Consumption of diets with inappropriate macronutrient profiles has been associated with increased energy expenditure, ill health, failed reproduction, and premature death. Consequently, we conducted feeding and preference trials with giant pandas and sloth bears, a termite and ant-feeding specialist. Both giant pandas and sloth bears branched off from the ursid lineage a million or more years before polar bears and brown bears. We found that giant pandas are low-protein, high-carbohydrate omnivores, whereas sloth bears are low-protein, high-fat omnivores. The preference for low protein diets apparently occurred early in the evolution of ursids and may have been critical to their world-wide spread.
全世界有 8 种熊，它们的饮食种类繁多。有些是专门以某种特定食物或环境为食的专家，它们具有广泛的解剖学和生理学适应性，例如北极熊（Ursus maritimus）、大熊猫（Ailuropoda melanoleuca）和懒熊（Melursus ursinus），而其余的则是杂食动物。尽管熊科动物是从高蛋白的肉食动物进化而来的，但我们假设它们都已经成为了低蛋白的宏量营养素杂食动物。这种饮食策略已经在北极熊和棕熊（Ursus arctos）中得到了描述，但最近对大熊猫的研究表明，它们对宏量营养素的选择是其祖先高蛋白肉食动物的选择。食用不适当的宏量营养素谱的饮食与增加能量消耗、健康状况不佳、繁殖失败和过早死亡有关。因此，我们对大熊猫和懒熊进行了喂养和偏好试验，这是一种以白蚁和蚂蚁为食的专家。大熊猫和懒熊与北极熊和棕熊在 100 万年前或更早的时候就从熊科动物的谱系中分支出来。我们发现，大熊猫是低蛋白、高碳水化合物的杂食动物，而懒熊则是低蛋白、高脂肪的杂食动物。对低蛋白饮食的偏好显然在熊科动物的进化早期就出现了，这对它们在全球范围内的传播可能至关重要。
