Abstract: Comparing the diet of sympatric carnivorous species can reveal their differences and degree of overlap in resource utilization, which is an important approach to understanding the interactions among species and the stability of ecosystems. This study analyzes the species identification, dietary composition, similarity, and niche overlap of 338 scat samples collected in the Altun Mountains Nature Reserve using DNA metabarcoding technology. Eight carnivorous species were identified, including snow leopard (Panthera uncia), Eurasian lynx (Lynx lynx), wolf (Canis lupus), dhole (Cuon alpinus), red fox (Vulpes vulpes), Tibetan fox (V. ferrilata), brown bear (Ursus arctos), and stone marten (Martes foina). A total of 11 orders and 22 prey species were identified, with Cetartiodactyla (36. 59%) and Lagomorpha (24. 39%) having higher relative frequency of occurrence in the carnivorous species diet at order level. Blue sheep (Pseudois nayaur) was the most frequently detected prey species in the Cetartiodactyla order, and woolly hares (Lepus oiostolus) were the most frequently detected prey species in the Lagomorpha order. At the species level, Kiang (Equus kiang) was the most frequently detected prey species among all food categories, accounting for 20. 12% of the carnivorous species diet. Among carnivore species, brown bear and wolf had the highest dietary overlap (O_jk= 0. 797), followed by snow leopard and dhole (O_jk= 0. 764), indicating a competitive relationship in the utilization of food resources, while Tibetan fox and red fox had relatively low dietary overlap. In this study, the dietary composition and niche partitioning of carnivores in Altun Mountain National Nature Reserve were obtained, which is helpful to better understand the relationship of competition and coexistence between different species and provide scientific basis for species conservation.

Key words: Nutritional niche, Interspecific competition, Species identification, Dietary composition, DNA metabarcoding

摘要： 比较同域食肉目动物的食性能够揭示它们在资源利用上的差异和重叠程度，是了解物种间相互作用和生态系统稳定性的重要途径。本研究利用DNA宏条形码技术，对在阿尔金山国家级自然保护区内收集的338份食肉目动物粪便样品进行物种鉴定及食性组成、相似性和营养生态位重叠分析。结果共鉴定出8种食肉目动物，分别为雪豹(Panthera uncia)、猞猁(Lynx lynx)、狼(Canis lupus)、豺(Cuon alpinus)、赤狐(Vulpes vulpes)、藏狐(V.fer-rilata)、棕熊(Ursus arctos)和石貂(Martes foina)。共鉴定出11目22种猎物，其中鲸偶蹄目(36.59%)和兔形目(24.39%)在食肉目动物食谱中出现频率最高，岩羊(Psuedois nayaur)是鲸偶蹄目中相对出现频率最高的物种，灰尾兔(Lepus oiostolus)是兔形目中相对出现频率最高的物种。藏野驴(Equus kiang)是相对出现频率最高的猎物，占食肉目动物食谱的20.12%。在不同食肉目动物物种间，棕熊与狼食性重叠最高(O_jk=0.797)，其次是雪豹与豺(O_jk=0.764)，表明这些物种间存在明显的食物资源竞争；而藏狐和赤狐等物种间的食性重叠相对较低，表明这些物种间可能形成了营养生态位分化。本研究掌握了阿尔金山国家级自然保护区食肉目动物的食性组成及其营养生态位分化，有助于更好地理解不同物种间的竞争和共存关系，并为物种保护提供科学依据。

关键词: 营养生态位, 种间竞争, 物种鉴定, 食性组成, DNA宏条形码