Raw data Frozen & Borax_Specimens from All-a-glow: spectral characteristics confirm widespread fluorescence for mammals

Mammalian fluorescence has been reported from numerous species of monotreme, marsupial and placental mammal. However, it is unknown how widespread this phenomenon is among mammals, it is unclear for many species if these observations of ‘glowing’ are true fluorescence and the biological function of fluorescence remains undetermined. We examined a wide range of mammal species held in a museum collection for the presence of apparent fluorescence using UV light, and then analysed a subset of preserved and non-preserved specimens by fluorescent spectroscopy at three different excitation wavelengths to assess whether the observations were fluorescence or optical scatter, and the impact of specimen preservation. We also evaluated if fluorescence was related to biological traits. We found that fluorescence is widespread in mammalian taxa; we identified examples of the phenomena among 125 species representing all 27 living mammalian orders and 79 families. For a number of model species, there was no evidence of a corresponding shift in the emission spectra when the wavelength of excitation was shifted, suggesting that observations of ‘glowing’ mammals were indeed fluorescence. Preservation method impacted the intensity of fluorescence. Fluorescence was most common and most intense among nocturnal species and those with terrestrial, arboreal and fossorial habits, with more of their body being more fluorescent. It remains unclear if fluorescence has any specific biological role for mammals. It appears to be an ubiquitous property of unpigmented fur and skin but may function to make these areas appear brighter therefore enhance visual signalling, especially for nocturnal species.

已有研究报道单孔目（Monotreme）、有袋目（Marsupial）以及胎盘类哺乳动物（Placental mammal）的多个物种存在荧光现象。然而，目前尚不明确该现象在哺乳动物类群中的分布广度；针对诸多物种而言，其"发光"观测结果是否为真正的荧光，以及荧光的生物学功能均尚未明确。本研究利用紫外光（UV light）对馆藏博物馆标本中的大量哺乳动物物种进行潜在荧光检测；随后选取部分保存与未保存的标本，采用三种不同激发波长（excitation wavelength）的荧光光谱法（fluorescent spectroscopy）进行分析，以甄别观测到的发光现象属于荧光还是光学散射（optical scatter），并评估标本保存方式的影响。此外，本研究还探究了荧光现象与生物学性状之间的关联。研究结果表明，荧光现象在哺乳动物类群中广泛分布：本研究在涵盖现存全部27个哺乳动物目、79个科的125个物种中均发现了荧光现象。针对多个模式物种（model species），当激发波长改变时，其发射光谱（emission spectra）未出现对应偏移，这表明此前观测到的"发光"哺乳动物现象确为荧光。标本保存方式会影响荧光强度。在夜行性物种以及陆生、树栖、穴居物种中，荧光现象最为普遍且强度最高，其身体更多区域呈现荧光。目前仍不清楚荧光对哺乳动物是否具有特定生物学功能。荧光似乎是无色素皮毛与皮肤的普遍属性，其可能通过使这些区域更明亮来增强视觉信号传递，尤其对夜行性物种而言。