Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut.
Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Cumbayá, Quito, Ecuador.
Mol Ecol. 2019 May;28(9):2441-2450. doi: 10.1111/mec.15088. Epub 2019 Apr 25.
The gut microbiota of animal hosts can be influenced by environmental factors, such as unnatural food items that are introduced by humans. Over the past 30 years, human presence has grown exponentially in the Galapagos Islands, which are home to endemic Darwin's finches. Consequently, humans have changed the environment and diet of Darwin's finches, which in turn, could affect their gut microbiota. In this study, we compared the gut microbiota of two species of Darwin's finches, small ground finches (Geospiza fuliginosa) and medium ground finches (Geospiza fortis), across sites with and without human presence, where finches prefer human-processed and natural food, respectively. We predicted that: (a) finch microbiota would differ between sites with and without humans due to differences in diet, and (b) gut microbiota of each finch species would be most similar where finches have the highest niche overlap (areas with humans) compared to the lowest niche overlap (areas without humans). We found that gut bacterial community structure differed across sites and host species. Gut bacterial diversity was most distinct between the two species at the site with human presence compared to the site without human presence, which contradicted our predictions. Within host species, medium ground finches had lower bacterial diversity at the site with human presence compared to the site without human presence and bacterial diversity of small ground finches did not differ between sites. Our results show that the gut microbiota of Darwin's finches is affected differently across sites with varying human presence.
动物宿主的肠道微生物群可以受到环境因素的影响，例如人类引入的非自然食物。在过去的 30 年中，人类在加拉帕戈斯群岛的数量呈指数级增长，达尔文雀的特有种就在这里。因此，人类改变了达尔文雀的环境和饮食，这反过来可能会影响它们的肠道微生物群。在这项研究中，我们比较了有人类和没有人类存在的两个达尔文雀种（小地雀和中地雀）的肠道微生物群，在有人类和没有人类的地方，雀类分别更喜欢人类加工的和自然的食物。我们预测：（a）由于饮食的不同，雀类的微生物群在有人类和没有人类的地方会有所不同；（b）每种雀类的肠道微生物群在有人类的地方（高生态位重叠区）与在没有人类的地方（低生态位重叠区）的相似度最高。我们发现，肠道细菌群落结构在不同地点和宿主物种之间存在差异。与没有人类存在的地方相比，在有人存在的地方，两种雀类的肠道细菌多样性差异最大，这与我们的预测相反。在同一物种内，与没有人类存在的地方相比，中地雀在有人存在的地方的细菌多样性较低，而小地雀的细菌多样性在不同地点没有差异。我们的研究结果表明，在有不同人类存在的地方，达尔文雀的肠道微生物群受到不同的影响。
