Species range expansions are crucial for understanding niche formation and the interaction with the environment. Here, we studied the bumblebee Bombus haematurus Kriechbaumer, 1870, a species historically distributed from northern Serbia through northern Iran which has very recently started expanding north-westwards into Central Europe without human-mediated dispersal (i.e., it is a natural spread). After updating the global distribution of this species, we investigated if niche shifts took place during this range expansion between newly colonized and historical areas. In addition, we have explored which climatic factors may have favoured the natural range expansion of the species. Our results indicated that Bombus haematurus has colonized large territories in 7 European countries outside the historical area in the period from the 1980s to 2018, a natural expansion over an area that equals 20% of the historical distribution. In addition, this bumblebee performs generalism in flower visitation and it occurs in different habitats, although a preference for forested areas clearly emerges. The land-use associated with the species in the colonized areas is similar to the historical distribution, indicating that no major niche shifts occurred during the spread. Furthermore, in recently colonized localities, the range expansion was associated with warming temperatures during the winter and also during both queen overwintering and emergence phases. These findings document a case of natural range expansion due to environmental change rather than due to niche shifts, and specifically they suggest that warmer winters could be linked to the process of natural colonization of new areas. This article is protected by copyright. All rights reserved.

中文翻译：

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大黄蜂 Bombus haematurus 向中欧的西北范围扩张与温暖的冬季和生态位保守有关

物种范围扩展对于理解生态位形成和与环境的相互作用至关重要。在这里，我们研究了 1870 年的大黄蜂 Bombus haematurus Kriechbaumer，该物种历史上分布于塞尔维亚北部到伊朗北部，最近开始向西北扩展到中欧，而没有人类介导的传播（即，它是一种自然传播）。在更新了该物种的全球分布后，我们调查了在新殖民区和历史区之间的范围扩展期间是否发生了生态位变化。此外，我们还探讨了哪些气候因素可能有利于该物种的自然范围扩大。我们的研究结果表明，在 1980 年代至 2018 年期间，Bombus haematurus 在历史区域之外的 7 个欧洲国家的大片领土上进行了殖民，在相当于历史分布的 20% 的区域上的自然扩张。此外，这种大黄蜂在探花方面表现出普遍性，它出现在不同的栖息地，尽管明显偏爱森林地区。与殖民地区物种相关的土地利用与历史分布相似，表明在传播过程中没有发生重大的生态位变化。此外，在最近被殖民的地区，范围的扩大与冬季以及女王越冬和羽化阶段的温度升高有关。这些发现记录了一个由于环境变化而不是生态位变化引起的自然范围扩大的案例，特别是它们表明温暖的冬天可能与新地区的自然殖民过程有关。本文受版权保护。版权所有。