Molecular versus microscopic analyses tell different stories of little brown bat (<em>Myotis lucifugus</em>) diet in Alaska

Populations of wide-ranging species on the edge of their geographic range may experience environmental conditions unlike those of conspecifics from the core of the range. We conducted a study on the diet of little brown bats (Myotis lucifugus) near the northern edge of their range in Alaska, USA, using molecular fecal dietary techniques and compared these results to a previous diet study using microscopic analysis of the same samples. Molecular dietary analysis suggested that M. lucifugus in this population rely heavily on flies (Diptera), moths (Lepidoptera), and caddisflies (Trichoptera). Our results are consistent with other studies in the insect orders eaten but differ in the relative importance of those orders compared with molecular analyses of diet from M. lucifugus populations nearer the core species range. Our results also contrast with microscopic assessments of diet from these Alaskan samples, which identified spiders (Araneae) as the primary prey item for this population. Importantly, our study demonstrates how different types of analyses can yield different characterizations of diet, even from the same samples.分布范围广泛的物种，其地理分布边缘的种群所经历的环境条件，可能与该物种分布核心区域的同种个体所处的环境截然不同。我们针对美国阿拉斯加州境内处于分布北缘的小棕蝠（Myotis lucifugus）种群开展饮食研究，采用分子粪便饮食分析技术，并将本次研究结果与此前针对同一样本开展的显微分析饮食研究进行对比。分子饮食分析结果显示，该种群的小棕蝠主要以双翅目（Diptera）昆虫、鳞翅目（Lepidoptera）蛾类以及毛翅目（Trichoptera）石蛾为食。本研究结果与其他针对此类昆虫类群的研究结论相符，但与分布核心区域小棕蝠种群的分子饮食分析结果相比，各昆虫类群的相对重要性存在差异。此外，本研究结果与针对这些阿拉斯加样本开展的显微饮食评估结果相悖，后者将蜘蛛（Araneae）认定为该种群的主要猎物。值得注意的是，本研究证实了即便针对同一样本，不同类型的分析方法也可能得出不同的饮食特征描述。