Data from: No trade-offs in interspecific interference ability and predation susceptibility in newt larvae

Coexistence of species with similar requirements is allowed, among others, through trade-offs between competitive ability and other ecological traits. Although interspecific competition is based on two mechanisms, exploitation of resources and physical interference, trade-off studies largely consider only species’ ability to exploit resources. Using a mesocosm experiment, we examined the trade-off between interference competition ability and susceptibility to predation in larvae of two newt species, Ichthyosaura alpestris and Lissotriton vulgaris. In the presence of heterospecifics, L. vulgaris larvae slowed somatic growth and developmental rates, and experienced a higher frequency of injuries than in conspecific environments which suggests asymmetrical interspecific interference. During short-term predation trials, L. vulgaris larvae suffered higher mortality than I. alpestris. Larvae of the smaller species, L. vulgaris, had both lower interference and antipredator performance than the larger I. alpestris, which suggests a lack of trade-off between interference competition ability and predator susceptibility. We conclude that interference competition may produce a positive rather than negative relationship with predation susceptibility, which may contribute to the elimination of subordinate species from common habitats.

具有相似生态需求的物种能够实现共存，除却其他诸多影响因素外，这可通过竞争能力与其他生态性状之间的权衡（trade-off）得以实现。尽管种间竞争（interspecific competition）基于资源利用与物理干扰两大机制，但现有权衡研究大多仅关注物种的资源利用能力。本研究借助中型生态系统实验（mesocosm experiment），探究了两种蝾螈——阿尔卑斯蝾螈（Ichthyosaura alpestris）与普通欧螈（Lissotriton vulgaris）——的幼虫在干扰竞争能力与捕食易感性（susceptibility to predation）之间的权衡。当暴露于异种个体时，普通欧螈幼虫的体细胞生长速率与发育速率均出现放缓，且受伤频率显著高于同种个体饲养环境，这表明二者存在不对称种间干扰（asymmetrical interspecific interference）。在短期捕食试验中，普通欧螈幼虫的死亡率显著高于阿尔卑斯蝾螈幼虫。体型更小的普通欧螈幼虫，其干扰竞争能力与反捕食表现（antipredator performance）均弱于体型更大的阿尔卑斯蝾螈幼虫，这表明二者之间并不存在干扰竞争能力与捕食易感性之间的权衡。本研究结论表明，干扰竞争与捕食易感性之间可能呈现正向而非负向关联，这或可导致劣势物种被从常见生境中排挤出去。