Low-light adapted bees are substantially understudied components of the bee fauna, particularly in Australia. Whilst several species in Australia are thought to be adapted to low-light conditions, explicit records of these taxa actually foraging at twilight or night are absent from the scientific literature. We present the first observations of Australian bees foraging in low-light conditions as well as the first evidence of low-light foraging behaviour in the colletid bee subfamily, Hylaeinae. Using morphometrics of Australian and more broadly-distributed diurnal, facultative low-light and obligate low-light adapted bees, we explore the use of morphological traits to objectively assess possible low-light behaviour and corroborate low-light collection events. Our results show that it is possible to morphologically distinguish between diurnal and low-light adapted bees, and that there is a spectrum of characters that are associated with low light conditions. We use GIS to show that low-light adapted species occur mostly in the tropics, but that some species have subtropical, arid and even temperate distributions. As low-light foraging behaviour in bees is infrequently reported, it appears that low-light foraging behaviour is more common than currently appreciated, highlighting the need for extended bee-sampling periods and more consistent collection data to increase the understanding of this little-understood aspect of bee behaviour.

中文翻译：

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昼夜和低光觅食蜜蜂的形态测量比较和新观察

适应弱光的蜜蜂是蜜蜂动物群的重要组成部分，尤其是在澳大利亚。虽然澳大利亚的几个物种被认为适应弱光条件，但科学文献中没有这些分类群在黄昏或夜间觅食的明确记录。我们展示了澳大利亚蜜蜂在弱光条件下觅食的首次观察结果，以及蜂科蜜蜂亚科 Hylaeinae 弱光觅食行为的第一个证据。使用澳大利亚和更广泛分布的昼夜、兼性弱光和专性弱光适应蜜蜂的形态测量学，我们探索使用形态特征客观评估可能的弱光行为并证实弱光收集事件。我们的结果表明，可以在形态上区分昼夜适应和低光适应性蜜蜂，并且存在与低光条件相关的一系列特征。我们使用 GIS 显示适应弱光的物种主要出现在热带地区，但有些物种具有亚热带、干旱甚至温带的分布。由于很少报道蜜蜂的弱光觅食行为，因此弱光觅食行为似乎比目前所认识的更常见，这突出表明需要延长蜜蜂采样期和更一致的收集数据，以增加对这种鲜为人知的了解蜜蜂行为的一个方面。我们使用 GIS 显示适应弱光的物种主要出现在热带地区，但有些物种具有亚热带、干旱甚至温带的分布。由于很少报道蜜蜂的弱光觅食行为，因此弱光觅食行为似乎比目前所认识的更常见，这突出表明需要延长蜜蜂采样期和更一致的收集数据，以增加对这种鲜为人知的了解蜜蜂行为的一个方面。我们使用 GIS 显示适应弱光的物种主要出现在热带地区，但有些物种具有亚热带、干旱甚至温带的分布。由于很少报道蜜蜂的弱光觅食行为，因此弱光觅食行为似乎比目前所认识的更常见，这突出表明需要延长蜜蜂采样期和更一致的收集数据，以增加对这种鲜为人知的了解蜜蜂行为的一个方面。