Tran Thi Nhat Quyen, Jackson Michelle C, Sheath Danny, Verreycken Hugo, Britton J Robert
Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, BH12 5BB, UK.
Department of Zoology and Entomology, Centre for Invasion Biology, University of Pretoria, Gauteng, South Africa.
J Anim Ecol. 2015 Jul;84(4):1071-80. doi: 10.1111/1365-2656.12360. Epub 2015 Mar 30.
Ecological theory attempts to predict how impacts for native species arise from biological invasions. A fundamental question centres on the feeding interactions of invasive and native species: whether invasion will result in increased interspecific competition, which would result in negative consequences for the competing species, or trophic niche divergence, which would facilitate the invader's integration into the community and their coexistence with native species. Here, the feeding interactions of a highly invasive fish, topmouth gudgeon Pseudorasbora parva, with three native and functionally similar fishes were studied to determine whether patterns of either niche overlap or divergence detected in mesocosm experiments were apparent between the species at larger spatial scales. Using stable isotope analysis, their feeding relationships were assessed initially in the mesocosms (1000 L) and then in small ponds (<400 m(2) ) and large ponds (>600 m(2) ). In the mesocosms, a consistent pattern of trophic niche divergence was evident between the sympatric fishes, with niches shifting further apart in isotopic space than suggested in allopatry, revealing that sharing of food resources was limited. Sympatric P. parva also had a smaller niche than their allopatric populations. In eight small ponds where P. parva had coexisted for several years with at least one of the fish species used in the mesocosms, strong patterns of niche differentiation were also apparent, with P. parva always at a lower trophic position than the other fishes, as also occurred in the mesocosms. Where these fishes were sympatric within more complex fish communities in the large ponds, similar patterns were also apparent, with strong evidence of trophic niche differentiation. Aspects of the ecological impacts of P. parva invasion for native communities in larger ponds were consistent with those in the mesocosm experiments. Their invasion resulted in divergence in trophic niches, partly due to their reduced niche widths when in sympatry with other species, facilitating their coexistence in invaded ecosystems. Our study highlights the utility of controlled mesocosm studies for predicting the trophic relationships that can develop from introductions of non-native species into more complex ecosystems and at larger spatial scales.
生态理论试图预测生物入侵对本地物种的影响是如何产生的。一个基本问题集中在入侵物种与本地物种的摄食相互作用上：入侵是否会导致种间竞争加剧，进而对竞争物种产生负面影响，还是会导致营养生态位分化，从而促进入侵者融入群落并与本地物种共存。在此，研究了一种高度入侵性鱼类——麦穗鱼（Pseudorasbora parva）与三种本地且功能相似的鱼类的摄食相互作用，以确定在中宇宙实验中检测到的生态位重叠或分化模式在更大空间尺度上的物种之间是否明显。利用稳定同位素分析，首先在中宇宙（1000升）中评估它们的摄食关系，然后在小池塘（<400平方米）和大池塘（>600平方米）中进行评估。在中宇宙中，同域分布的鱼类之间明显存在营养生态位分化的一致模式，其生态位在同位素空间中的距离比异域分布时更远，这表明食物资源的共享是有限的。同域分布的麦穗鱼的生态位也比其异域种群的生态位小。在8个小池塘中，麦穗鱼与至少一种用于中宇宙实验的鱼类共存了数年，生态位分化的强烈模式也很明显，麦穗鱼的营养级位置总是低于其他鱼类，这与中宇宙实验中的情况相同。在大池塘中更复杂的鱼类群落中，当这些鱼类同域分布时，类似的模式也很明显，有强有力的证据表明存在营养生态位分化。麦穗鱼入侵对大池塘中本地群落的生态影响方面与中宇宙实验中的情况一致。它们的入侵导致了营养生态位的分化，部分原因是与其他物种同域分布时其生态位宽度减小，这有利于它们在入侵生态系统中共存。我们的研究强调了受控中宇宙研究在预测非本地物种引入到更复杂生态系统及更大空间尺度时可能形成的营养关系方面的实用性。
