Exploitative competition implies an indirect interaction in which a resource exploited by one species is not available for another; e.g., when species share diet or habitat. It plays a key role in community structure and dynamics. Here we evaluated the niche overlap between the exotic aoudad (Ammotragus lervia) and the native Iberian ibex (Capra pyrenaica) where the species coexist in the Iberian Peninsula, along two main dimensions, the trophic niche and the environmental niche. Then we assessed the spatial segregation of the species. We expected that if a niche overlap was high, competition could drive spatial segregation to allow co-existence. We analyzed their trophic niche overlap by using the content of stable isotopes δ¹⁵N and δ¹³C in the hair of both species. To establish environmental niche competition, we compared the similarity in their habitat, estimated by environmental niche models based on the fine-scale presence records of each species obtained from field surveys. To test if spatial segregation occurred, we analyzed both species’ co-occurrence. Our results indicated that both species shared a similar trophic niche measured by stable isotopes, both species showed a similar distribution of suitable areas, and that both species’ environmental niches were more similar than expected. Finally, a negative spatial association was found between the aoudad and Iberian ibex. These results reveal that both species are ecologically similar and suggest that fine-scale spatial segregation might have favoured their co-existence in semiarid Mediterranean mountains. Our results show that integrating information on trophic and environmental niche overlap with fine scale spatial distribution might improve the study of competitive interactions among wild ungulates.

剥削性竞争是一种间接的相互作用，一种物种无法利用另一种物种的资源。例如，当物种共享饮食或栖息地时。它在社区结构和动态中起着关键作用。在这里，我们评估了外来物种（Ammotragus lervia）和本土伊比利亚高地山羊（Capra pyrenaica）之间的生态位重叠，沿两个主要方面，即营养生态位和环境生态位，该物种共存于伊比利亚半岛。然后，我们评估了物种的空间隔离。我们预计，如果利基重叠率很高，竞争会推动空间隔离，从而实现共存。我们用的稳定同位素含量分析其营养生态位重叠δ ¹⁵ N和δ ¹³C在两种物种的头发中。为了建立环境生态位竞争，我们根据环境生态位模型根据从实地调查获得的每种物种的精细存在记录，比较了它们栖息地的相似性。为了测试是否发生了空间隔离，我们分析了两种物种的同时出现。我们的结果表明，两个物种都具有通过稳定同位素测得的相似的营养生态位，两个物种都显示出相似的合适区域分布，并且两个物种的环境生态位都比预期的更为相似。最后，在原始和伊比利亚山羊之间发现了负的空间联系。这些结果表明，这两个物种在生态上都相似，并表明精细的空间隔离可能有利于它们在半干旱地中海山区的共存。