Trophic consequences of introduced species: comparative impacts of increased inter-specific versus intra-specific competitive interactions

1. Invasive species can cause substantial ecological impacts on native biodiversity. Whilst ecological theory attempts to explain the processes involved in the trophic integration of invaders into native food webs and their competitive impacts on resident species, results are equivocal. In addition, quantifying the relative strength of impacts from non-native species (inter-specific competition) versus the release of native conspecifics (intra-specific competition) is important but rarely completed. 2. Two model non-native fishes, the globally invasive Cyprinus carpio and Carassius auratus, and the model native fish Tinca tinca, were used in a pond experiment to test how increased intra- and inter-specific competition influenced trophic niches and somatic growth rates. This was complemented by samples collected from three natural fish communities where the model fishes were present. The isotopic niche, calculated using stable isotope data, represented the trophic niche. 3. The pond expe...1. 外来入侵物种可对本土生物多样性造成显著生态影响。尽管生态学理论尝试阐释入侵物种融入本土食物网的营养整合过程，及其对本地常驻物种的竞争效应，但相关研究结论仍莫衷一是。此外，量化外来物种（种间竞争，inter-specific competition）与本土同种个体种群释放（种内竞争，intra-specific competition）所产生影响的相对强度具有重要科学价值，但此类研究极少开展。 2. 本研究选取两种全球入侵的外来模式鱼类——普通鲤（Cyprinus carpio）与鲫（Carassius auratus），以及本土模式鱼类丁鱥（Tinca tinca），开展池塘实验以探究种内与种间竞争加剧对营养生态位（trophic niche）及躯体生长速率的影响。本研究辅以采集自三个分布有该模式鱼类的自然鱼类群落的样本，以稳定同位素（stable isotope）数据计算得到的同位素生态位（isotopic niche）表征营养生态位。 3. 本次池塘实验……