Environmental Archaeology Lab, Department of Historical, Philosophical and Religious Studies, Umeå University, Biblioteksgränd 3, 907 36 Umeå, Sweden; Senckenberg Research Institute and Natural History Museum Frankfurt, Department of River Ecology and Conservation, Clamecystrasse 12, 63571 Gelnhausen, Germany.
Senckenberg Research Institute and Natural History Museum Frankfurt, Department of River Ecology and Conservation, Clamecystrasse 12, 63571 Gelnhausen, Germany; University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, 389 25 Vodňany, Czech Republic.
Sci Total Environ. 2022 Mar 1;810:151770. doi: 10.1016/j.scitotenv.2021.151770. Epub 2021 Nov 19.
Biotic homogenization is one of the key aspects of the current biodiversity crisis. Here we analyzed the trends of three facets of niche homogenization, i.e. niche specialization, trait α-diversity and spatial β-diversity, over a period of 25 years (1990-2014) using a large dataset of 3782 stream benthic invertebrate samples collected from central European low-mountain streams. We studied a set of traits describing the ecological niche of species and their functions: body size, feeding groups, substrate preferences, flow preferences, stream zonation preferences and saprobity. Trait composition changed significantly during the study period, and we identified an overall increase in niche homogenization. Specifically, community niche specialization significantly decreased by 20.3% over the 25-year period, with declines ranging from -16.0 to -40.9% for zonation-, flow-, substrate-preferences, body size and feeding traits. Trait diversity did not change significantly, although we recorded significant decreases by -14.2% and -10.2% for flow- and substrate-preference and increases by 5.8% and 22.6% for feeding traits and zonation preference over the study period. Trait spatial β-diversity significantly decreased by -53.0%, with substrate-preference, feeding groups and flow-preference traits declining from -61.9% to -75.3% over the study period. This increased niche homogenization is likely driven by the increase of down-stream typical taxa, which are favored by warming temperatures. Further, it is in apparent contradiction with the recorded increase in abundance (+35.9%) and taxonomic richness (+39.2%) over the same period. Even such increases do not safeguard communities from undergoing niche homogenization, indicating that recovery processes may differ with regard to community taxonomic composition and traits. Our results emphasize the complexity of community responses to global change and warrant caution when founding conclusions based solely on single community metrics.
生物同质化是当前生物多样性危机的关键方面之一。在这里，我们使用来自中欧低山溪流的 3782 个溪流底栖无脊椎动物样本的大型数据集，分析了生态位特化、特征 α 多样性和空间 β 多样性三个方面的趋同趋势，时间跨度为 25 年（1990-2014 年）。我们研究了一组描述物种生态位及其功能的特征：体型、摄食群、基质偏好、水流偏好、溪流分区偏好和污化度。特征组成在研究期间发生了显著变化，我们确定了生态位同质化的总体增加。具体而言，群落生态位特化在 25 年内显著下降了 20.3%，分区偏好、水流偏好、基质偏好、体型和摄食特征的下降范围分别为-16.0 至-40.9%。特征多样性没有显著变化，尽管我们记录到水流偏好和基质偏好分别显著下降了-14.2%和-10.2%，而摄食特征和分区偏好分别显著增加了 5.8%和 22.6%。特征空间 β 多样性显著下降了 53.0%，其中基质偏好、摄食群和水流偏好特征在研究期间下降了-61.9%至-75.3%。这种生态位同质化的增加可能是由变暖温度所青睐的下游典型类群的增加所驱动的。此外，这与同期记录的丰度增加（+35.9%）和分类丰富度增加（+39.2%）明显矛盾。即使有这样的增加，也不能保护群落免受生态位同质化的影响，这表明恢复过程可能在群落的分类组成和特征方面存在差异。我们的研究结果强调了群落对全球变化的复杂反应，并在仅基于单一群落指标得出结论时需要谨慎。
