Weak effect of urbanisation on bdelloid rotifers living in lichens

Human activities have an overwhelming impact on the natural environment, leading to a deep biodiversity crisis whose effects range from genes to ecosystems. We here analysed the effect of such anthropogenic impacts on bdelloid rotifers (Rotifera: Bdelloidea), for whom these effects are poorly understood. We targeted bdelloid rotifers living in lichen patches across urbanisation gradients in Flanders and Brussels (Belgium). Urbanisation was measured as the percentage of built-up area across different spatial scales, at circles from 50 m to 3,200 m of radius around the lichen. Urbanisation effects on biodiversity were assessed on abundance, species richness, and community-weighted mean body size of bdelloid rotifers, as well as on genetic diversity of one of the most common and widespread bdelloid species, Adineta vaga. Overall, no negative effect of urbanisation was found at any diversity level and at any spatial scale. Counterintuitively, built-up area quantified at the largest spatial scale had a positive effect on abundance. These results leave open the question of whether negative effects of urbanisation are present for bdelloid rotifers, or if such effects are only visible at even larger spatial scales.人类活动对自然环境产生了压倒性影响，引发了波及从基因到生态系统全层级的严重生物多样性危机。本研究针对此类人为活动对蛭形轮虫（Rotifera: Bdelloidea）的影响展开分析，目前学界对这类影响的认知仍较为有限。研究对象为栖息于比利时佛兰德斯与布鲁塞尔地区不同城市化梯度下地衣斑块中的蛭形轮虫。城市化水平以各地衣斑块周边半径50米至3200米的不同空间尺度范围内的建成区占比进行量化。本研究从蛭形轮虫的种群丰度、物种丰富度、群落加权平均体型，以及分布最广泛的常见蛭形轮虫物种之一——迟钝旋轮虫（Adineta vaga）的遗传多样性这多个维度，评估了城市化对其生物多样性的影响。整体而言，在所有多样性维度与所有空间尺度下，均未观测到城市化产生负面影响。与直觉相悖的是，在最大空间尺度下量化得到的建成区占比对种群丰度呈现正向促进作用。本研究结果留下了待探讨的科学问题：城市化是否会对蛭形轮虫产生负面影响？抑或此类影响仅会在更大的空间尺度下才会显现？