The period of the Last Glacial Maximum (LGM) is characterised by severe cooling and extreme aridity in Australia. Australian temperate-adapted bees experienced entirely new conditions over the LGM; however, few studies focused on the response of these key pollinators and their dependent plants to the LGM in Australia. In this study, we investigated the impact of the LGM climatic conditions on the population histories of the Australian temperate exoneurine bees regarded as critical native pollinators in the continent. To address this issue, we first identified the bee species using a combination of morphological and molecular approaches including phylogenetic and species delimitation methods. The analyses revealed three exoneurine genera, including Brevineura, Exoneura and Inquilina. Our estimated divergence time between Exoneura and Inquilina was close to that of previous phylogenetic studies of the exoneurine bees, which used different dating methods. The haplotype network analyses indicated the geographical structuring of the haplotypes within Exonuera and Inquilina species. We then utilised Bayesian skyline analyses to reconstruct demographic histories of the genus Exoneura for which sufficient haplotype diversity was found. The results showed that the population size of Exoneura species remained unchanged over the LGM or even increased shortly before it. The wide geographical distribution of the exoneurine species in Australia and earlier development of genetic and physiological adaptations are discussed as possibilities that enabled the species to maintain their population sizes over the LGM.

中文翻译：

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澳大利亚温带外神经蜜蜂（膜翅目：蜂科）在末次冰川盛期的人口统计学稳定性

末次盛冰期 (LGM) 的特点是澳大利亚的严重降温和极度干旱。澳大利亚温带适应性蜜蜂在 LGM 期间经历了全新的条件；然而，很少有研究关注这些关键传粉媒介及其依赖植物对澳大利亚 LGM 的反应。在这项研究中，我们调查了 LGM 气候条件对澳大利亚温带外神经蜜蜂的种群历史的影响，这些蜜蜂被认为是非洲大陆的关键本地传粉者。为了解决这个问题，我们首先使用形态学和分子方法（包括系统发育和物种定界方法）的组合来确定蜜蜂物种。分析揭示了三个外神经元属，包括Brevineura、Exoneura和因奎利纳。我们估计的Exoneura和Inquilina之间的分歧时间接近于之前对 exoneurine 蜜蜂进行的系统发育研究，后者使用了不同的测年方法。单倍型网络分析表明Exonuera和Inquilina物种内单倍型的地理结构。然后，我们利用贝叶斯天际线分析来重建Exoneura属的人口统计历史，其中发现了足够的单倍型多样性。结果表明，Exoneura的种群规模物种在 LGM 期间保持不变，甚至在 LGM 之前不久增加。澳大利亚外神经元物种的广泛地理分布以及遗传和生理适应的早期发展被讨论为使该物种能够在 LGM 期间保持其种群规模的可能性。