Aput Laura M, Farji-Brener Alejandro G, Pirk Gabriela I
Centro Regional Universitario Bariloche, Universidad Nacional del Comahue, Río Negro, Bariloche, Argentina.
LIHO, Laboratorio Ecotono, INIBIOMA (CONICET-Universidad Nacional del Comahue), Río Negro, Bariloche, Argentina.
Environ Entomol. 2019 Jun 7;48(3):567-572. doi: 10.1093/ee/nvz022.
Invasive species may interact with resident species and disrupt previously established interactions, with effects on the whole community. If introduced seeds are selectively consumed by native granivores, this could limit the establishment or spread of invasive plants (biotic resistance), and reduce the predation pressure upon native seeds. We determined if the presence of introduced plants affects the diet and the seed preferences of the ant Pogonomyrmex carbonarius (Mayr) in a Patagonian steppe. We expected a higher proportion of introduced seeds in the diet of nests located in areas with a high abundance of introduced species (roadsides) than in nests located in low invaded areas. Diet composition was obtained by collecting items retrieved by workers to colonies and compared between areas of contrasting abundance of introduced species. Field-based choice experiments were performed to evaluate whether exotic seeds were preferred to native ones under a paired comparisons design. Native seeds predominated in the diet. A low proportion of introduced species were included only in colonies close to the road. Ants preferred native seeds to introduced ones, and showed a marked preference for seeds of the native grass Pappostipa speciosa (Trin. & Rupr.) Romasch. (Poaceae), typical of the Patagonian steppe. The presence of introduced plants had little influence on interactions of P. carbonarius with seeds in the Patagonian steppe. Therefore, this ant species would not exert a control on the studied introduced plants, illustrating a case of low biotic resistance to invasion by these species.
入侵物种可能与本地物种相互作用，破坏先前建立的相互作用，从而影响整个群落。如果引入的种子被本地食谷动物选择性地食用，这可能会限制入侵植物的定殖或扩散（生物抗性），并减轻对本地种子的捕食压力。我们研究了引入植物的存在是否会影响巴塔哥尼亚草原上的碳角猛蚁（Pogonomyrmex carbonarius，梅尔）的食物组成和种子偏好。我们预计，位于引入物种丰富地区（路边）的蚁巢的食物中，引入种子的比例会高于位于低度入侵地区的蚁巢。通过收集工蚁带回蚁群的食物来确定食物组成，并对引入物种丰度不同的地区进行比较。在配对比较设计下进行实地选择实验，以评估外来种子是否比本地种子更受青睐。本地种子在食物中占主导地位。只有靠近道路的蚁群中包含少量引入物种。蚂蚁更喜欢本地种子而非引入种子，并且对巴塔哥尼亚草原特有的本地草类——美丽针茅（Pappostipa speciosa， Trin. & Rupr.）Romasch.（禾本科）的种子表现出明显偏好。引入植物的存在对巴塔哥尼亚草原上碳角猛蚁与种子的相互作用影响很小。因此，这种蚂蚁不会对所研究的引入植物起到控制作用，这说明了该物种对这些物种入侵的生物抗性较低的情况。
