Temperature and livestock grazing trigger transcriptome responses in bumblebees along an elevational gradient

It is assumed that climate and land-use changes cause increasing stress to pollinators, which play pivotal roles in almost all terrestrial ecosystems, with consequences on population growth, diversity and ecosystem functions. While these responses to global change drivers are well located, the molecular pathways triggering the response are poorly understood. We analysed the transcriptomic response of Bombus lucorum workers in their systematic responses to temperature and livestock grazing, sampled along an elevational gradient from 650 – 1930 m.a.s.l., and from differently managed grassland sites (livestock grazing vs. unmanaged) in and around the National Park Berchtesgaden (German Alps). In total, 81 B. lucorum workers (Lowlands: 30; mid-elevation: 25; highlands: 26) were collected via sweep nets on 16 different study sites (lowlands: 6 study sites from 641-987 m a.s.l.; mid-elevations: 5 study sites from 1140-1420 m a.s.l; highlands: 5 study sites from 1579-1930 m a.s.l.) between end of July and mid of August 2019 between 9 am and 7 pm. We collected 5 workers per study site except for the highest site, where on one site less individuals were found, therefore on another site more individuals were captured.

学界普遍认为，气候变化与土地利用变化正持续加剧对传粉昆虫的胁迫压力；传粉昆虫在几乎所有陆地生态系统中均发挥关键作用，其种群增长、物种多样性与生态系统功能均会受到该胁迫的连锁影响。尽管传粉昆虫对全球变化驱动因子的响应已得到较为充分的解析，但触发这些响应的分子通路却鲜为人知。本研究针对明亮熊蜂（Bombus lucorum）工蜂对温度与家畜放牧的系统性响应展开转录组分析，实验样本沿650至1930 m.a.s.l.的海拔梯度采集，布设点位位于德国阿尔卑斯山区贝希特斯加登国家公园（National Park Berchtesgaden）及其周边的两类不同管理草地样地：家畜放牧样地与未管理样地。2019年7月末至8月中旬的每日9时至19时，研究人员通过扫网法在16个样地中共采集到81头明亮熊蜂工蜂，其中低海拔组30头、中海拔组25头、高海拔组26头；样地分组及海拔范围如下：低海拔样地6个，海拔区间为641至987 m.a.s.l.，中海拔样地5个，海拔区间为1140至1420 m.a.s.l.，高海拔样地5个，海拔区间为1579至1930 m.a.s.l.。每个样地原计划采集5头工蜂，但最高海拔组中有1个样地仅发现少量个体，因此研究人员在另一个样地额外采集了部分个体以补足样本量。