Microbial signatures of vertebrate visitation in floral nectar: a case study with two endemic Aotearoa New Zealand plant species

Microbes found in nectar and dispersed by animal visitors can mediate pollination and host fitness. While previous studies have characterised floral nectar microbiomes and their effects on invertebrate pollinators, fewer studies have focused on vertebrate pollinators, especially outside of the Northern Hemisphere. In Aotearoa New Zealand, vertebrates, such as birds and bats, are critical pollinators for many native plant species. Here, we present nectar microbiome profiles for two endemic, vertebrate-pollinated plant species in Aotearoa New Zealand, wharariki, mountain flax (<i>Phormium cookianum</i>), and pua o te Rēinga, wood rose (<i>Dactylanthus taylorii</i>). We used vertebrate exclusion treatments and camera traps to monitor visitation. Camera trap footage revealed silvereye (<i>Zosterops lateralis</i>), ship rat (<i>Rattus rattus</i>), and possum (<i>Trichosurus vulpecula)</i> visitation. We detected shifts in microbial species turnover in wood rose and varying relative abundances of fungal and bacterial taxa across the vertebrate exclusion treatments for both mountain flax and wood rose. However, we did not detect strong effects on floral nectar microbiome community composition or richness. Future work should move beyond profiling the microbial communities and identify fitness consequences and pollination outcomes, which could affect conservation and management decisions.

栖息于花蜜中、经动物访者携带传播的微生物可介导传粉过程并影响宿主适合度。既往研究已对花蜜微生物组（microbiome）及其对无脊椎动物传粉者的影响开展了表征分析，但针对脊椎动物传粉者的研究相对较少，尤其是在北半球以外的区域。在新西兰（奥特亚罗瓦），鸟类、蝙蝠等脊椎动物是诸多本土植物物种的关键传粉者。本研究提供了新西兰（奥特亚罗瓦）两种经脊椎动物传粉的特有植物的花蜜微生物组特征图谱：wharariki（山亚麻，<i>Phormium cookianum</i>）与pua o te Rēinga（木玫瑰，<i>Dactylanthus taylorii</i>）。我们设置了脊椎动物排除处理组，并利用相机陷阱监测植物的访花活动。相机陷阱录像显示，银眼鹟（<i>Zosterops lateralis</i>）、黑鼠（<i>Rattus rattus</i>）及帚尾袋貂（<i>Trichosurus vulpecula</i>）均存在访花行为。我们检测到木玫瑰的微生物物种更替发生变化，且在山亚麻和木玫瑰的脊椎动物排除处理组中，真菌与细菌类群的相对丰度均存在差异。然而，我们并未检测到这些处理对花蜜微生物组的群落组成或丰富度存在显著影响。未来研究应超越微生物群落的特征解析，探究其对宿主适合度及传粉结果的影响，这可为相关保护与管理决策提供科学依据。