A novel nectar drinking adaptation: Function and morphology of the grooved tongue of nectar-feeding Neotropical lonchophylline bats

一种新的花蜜饮用适应：食花蜜的新热带长茶碱蝙蝠的沟槽舌头的功能和形态

• 批准号: 464509708
• 负责人: Professor Dr. Marco Tschapka
• 金额: --
• 依托单位: Smithsonian Tropical Research Institute
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/464509708?language=en
• 关键词: novel; nectar; drinking; adaptation; Function

Morphological and behavioural specialisations on a nectar diet are mostly found in insects, however, there are also a few specialized flower-visiting mammals. Within the Neotropical leaf-nosed bats (Phyllostomidae), the two subfamilies Glossophaginae and the Lonchophyllinae show independently evolved adaptations towards nectarivory. Both share an elongation of the tongue, however, tongue morphology, and - as we could recently show - drinking behaviour differ distinctly between the subfamilies. Glossophagine bats have a brush-tipped tongue, where elongated papillae on the tip of the tongue aid in nectar uptake. These bats extend and withdraw their tongue repeatedly in a sinusoidal lapping movement when feeding at a flower. In contrast, the lonchophylline tongue lacks these hair-like papillae but shows two lateral longitudinal grooves. Recently we found that lonchophylline bats extend during a flower visit their tongue, immerse the tip into the nectar and then maintain this position without retractions to the end of the drinking bout, while nectar rises within the grooves into the mouth. The underlying mechanism of this drinking mode fits none of the so far described nectar uptake mechanisms. We hypothesised that nectar is transported within grooves through a combination of capillary forces and peristaltic muscle movements. We want to investigate the physiological base and potential ecological consequences of this unique drinking mode. On a physiological level, we first want to collect morphological data on the tongue grooves of different sized lonchophylline bat species by performing µCT (high resolution X-ray computed tomography) and SEM (scanning electron microscope) imaging. The obtained data will allow to develop a hypothetical fluid dynamic model based on the Hagen-Poiseuille equation, where fluid flow is just driven by capillarity. Additionally, we plan to perform behavioural experiments with lonchophylline bat species in Panama and Peru, including a motion analysis through high speed video. By comparing our model to empirical data on drinking performance of lonchophylline bats on artificial nectar with modified viscosity and surface tension we will determine the relative contribution of active mechanisms to nectar uptake. For assessing ecological consequences, we will analyse potential resource partitioning mechanisms between both subfamilies. Using 3D-printed artificial flowers with different nectar presentation we will compare the feeding performance of the subfamilies, using glossophagine bats from our colony at the Ulm University and lonchophylline bats in the field. The project provides unique opportunities to understand a novel, natural fluid transport system, to explore how foraging adaptations may affect resource partitioning and thus community ecology of nectar-feeding bat species, and might even be of interest for developing biomimetic micro pumps, e.g., for medical applications.

花蜜饮食的形态和行为专业化主要见于昆虫，然而，也有一些专门的访花哺乳动物。在新热带叶鼻蝙蝠（Phyllostomidae），两个亚科Glossophaginae和Lonchophyllinae显示独立进化的适应花蜜。两者都有舌头的伸长，然而，舌头的形态，以及-正如我们最近所展示的-饮用行为在亚科之间有明显的不同。舌蝠有一个刷尖的舌头，在舌尖上的细长乳头帮助花蜜的吸收。这些蝙蝠在觅食花朵时，会以正弦曲线的拍打动作反复地伸出和收回舌头。与此相反，lonchophylline舌缺乏这些毛状乳头，但显示两个横向纵向凹槽。最近，我们发现，lonchophylline蝙蝠延长在花访问他们的舌头，浸入尖端到花蜜，然后保持这个位置没有回缩到年底的饮用回合，而花蜜上升到口中的凹槽内。这种饮用模式的潜在机制不符合迄今为止描述的花蜜吸收机制。我们假设，花蜜是通过毛细管力和蠕动的肌肉运动的组合槽内运输。我们想研究这种独特的饮酒模式的生理基础和潜在的生态后果。在生理层面上，我们首先希望通过执行µCT（高分辨率X射线计算机断层扫描）和SEM（扫描电子显微镜）成像来收集不同大小的lonchophylline蝙蝠物种的舌槽的形态数据。所获得的数据将允许开发一个假设的流体动力学模型的基础上的哈根-Poietille方程，其中流体流动只是由毛细作用驱动。此外，我们计划在巴拿马和秘鲁用蝙蝠物种进行行为实验，包括通过高速视频进行运动分析。通过比较我们的模型的饮用性能的lonchophylline蝙蝠人工花蜜与改性粘度和表面张力的经验数据，我们将确定花蜜吸收的相对贡献的积极机制。为了评估生态后果，我们将分析两个亚科之间潜在的资源分配机制。使用具有不同花蜜呈现的3D打印人造花，我们将比较亚科的摄食性能，使用来自我们在乌尔姆大学的殖民地的glossophagine蝙蝠和野外的lonchophylline蝙蝠。该项目提供了独特的机会，以了解一种新的，自然的流体运输系统，探索觅食适应如何影响资源分配，从而影响花蜜喂养蝙蝠物种的群落生态，甚至可能对开发仿生微泵感兴趣，例如，用于医疗应用。