As cities expand, understanding how urbanization affects biodiversity is a key ecological goal. Yet, little is known about how host-associated microbial diversity responds to urbanization. We asked whether communities of microbial (bacterial and fungal) in floral nectar and sugar-water feeders and vectored by nectar-feeding birds—thus forming a metacommunity—differed in composition and diversity between suburban and rural gardens. Compared to rural birds, we found that suburban birds vectored different and more diverse bacterial communities. These differences were not detected in the nectar of common plant species, suggesting that nectar filters microbial taxa and results in metacommunity convergence. However, when considering all the nectar sources present, suburban beta diversity was elevated compared to rural beta diversity due to turnover of bacterial taxa across a plant species and sugar-water feeders. While fungal metacommunity composition and beta diversity in nectar were similar between suburban and rural sites, alpha diversity was elevated in suburban sites, which mirrored the trend of increased fungal alpha diversity on birds. These results emphasize the interdependence of host, vector, and microbial diversity and demonstrate that human decisions can shape nectar microbial diversity in contrasting ways for bacteria and fungi.

中文翻译：

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花蜜资源影响郊区和乡村花园中鸟类传播的微生物群落

随着城市的扩张，了解城市化如何影响生物多样性是一个关键的生态目标。然而，关于宿主相关微生物多样性如何对城市化作出反应知之甚少。我们询问了花蜜和糖水喂食器中的微生物群落（细菌和真菌）以及被喂食花蜜的鸟类引导的微生物群落（从而形成了一个元群落）是否在郊区和乡村花园之间的组成和多样性上有所不同。与农村鸟类相比，我们发现郊区鸟类携带不同且更多样化的细菌群落。在常见植物物种的花蜜中未检测到这些差异，这表明花蜜过滤微生物类群并导致群落趋同。然而，当考虑到所有存在的花蜜来源时，由于细菌类群在植物物种和糖水饲养者之间的更替，与农村 β 多样性相比，郊区 β 多样性有所提高。虽然郊区和农村地点的花蜜中的真菌群落组成和 β 多样性相似，但郊区地点的 alpha 多样性升高，这反映了鸟类真菌 alpha 多样性增加的趋势。这些结果强调了宿主、载体和微生物多样性之间的相互依赖性，并证明人类的决定可以通过与细菌和真菌形成对比的方式来塑造花蜜微生物的多样性。这反映了鸟类真菌α多样性增加的趋势。这些结果强调了宿主、载体和微生物多样性之间的相互依赖性，并证明人类的决定可以通过与细菌和真菌形成对比的方式来塑造花蜜微生物的多样性。这反映了鸟类真菌α多样性增加的趋势。这些结果强调了宿主、载体和微生物多样性之间的相互依赖性，并证明人类的决定可以通过与细菌和真菌形成对比的方式来塑造花蜜微生物的多样性。