An integrative approach to detect subtle trophic niche differentiation in the sympatric trawling bat species Myotis dasycneme and Myotis daubentonii

Bats are well known for species richness and ecological diversity thus they provide a good opportunity to study relationships and interaction between species. To assess interactions we consider distinct traits which are likely to be triggered by niche shape and evolutionary processes. We present data on the trophic niche differentiation between two sympatric European trawling bat species, Myotis dasycneme and M. daubentonii, incorporating a wide spectrum of methodological approaches. We measure morphological traits involved in foraging and prey handling performance including bite force, weight lifting capacity and wing morphology. We then measure resulting prey consumption using both morphological and molecular diet analysis. These species closely resemble each other in morphological traits however, subtle but significant differences were apparent in bite force and lift capacity which are related to differences in basic body and head size. Both morphological and molecular diet analyses show strong niche overlap. We detected subtle differences in less frequent prey items, as well as differences in the exploitation of terrestrial and aquatic-based prey groups. M. dasycneme feeds more on aquatic prey, like Chironomidae and their pupal stages, or the aquatic moth Acentria ephemerella. M. daubentonii feeds more on terrestrial prey, like Brachycera, or Coleoptera. This suggests that these bats use different micro-habitats within the habitat where they co-occur.

蝙蝠凭借极高的物种丰富度与生态多样性，成为研究物种间关系与相互作用的理想类群。为评估物种间的相互作用，本研究选取了可能由生态位（niche）格局与演化进程塑造的各类功能性状作为分析指标。本研究整合多维度研究方法，提供了两种同域分布的欧洲拖网型蝙蝠——沼鼠耳蝠（*Myotis dasycneme*）与水鼠耳蝠（*Myotis daubentonii*）的营养生态位（trophic niche）分化数据。研究测定了与觅食及猎物处理能力相关的形态性状，包括咬合力、负重能力与翼形态；随后通过形态学与分子生物学两种食性分析方法，对二者的猎物取食情况进行了测定。两种蝙蝠的形态性状整体高度相似，但咬合力与负重能力存在细微却显著的差异，该差异与二者基础体型及头部大小的分化相关。形态学与分子食性分析结果均显示，二者的生态位重叠度较高。研究还发现，二者在次要猎物类群的取食上存在细微差异，且对陆生与水生猎物类群的利用策略也有所不同：沼鼠耳蝠更多取食水生猎物，例如摇蚊科昆虫及其蛹期，或是水生蛾类水螟（*Acentria ephemerella*）；水鼠耳蝠则更多取食陆生猎物，例如短角亚目昆虫或鞘翅目昆虫。这表明两种蝙蝠在同域分布的栖息环境中，利用了不同的微生境。