Anthropogenic activities are supposed to reduce global biodiversity and negatively influence the development of diverse groups in the tree of life. Yet how agricultural management shapes the diversity of microscopic organisms and their evolution in the soil, especially at large spatial scale, remains unknown. Here, we investigated how agricultural land-use affected the biodiversity and the underlying evolutionary events of soil nematodes by comparing their communities in natural and agricultural soils covering a latitudinal transect spanning 2500 km across China. In natural habitats, nematode phylogenetic and taxonomic diversity and species richness showed a hump-shaped relationship with latitudes and peaked at 30° N, while in agricultural habitats those community matrices did not change across the studied latitudinal spectrum. Meanwhile, agricultural management reduced both diversity and richness of nematodes with the effect being more pronounced in subtropical zones. However, evolutionary diversification rates were greater in agricultural than in natural habitats across the entire latitudinal range. This was associated with reductions of soil organic carbon and nitrogen as well as shifts of nematode community compositions towards rapidly evolving taxa (r–strategists) in agricultural habitats. Together, our results suggest that the relatively unfavorable environmental status induced by agricultural management could accelerate the community-level speciation rates of nematodes through enriching rapidly evolving taxon. These insights increase our understanding of the systematic impacts of agricultural activities on soil biodiversity that might facilitate conservation and restoration policies for the purpose of sustainable agriculture.

人为活动应该减少全球生物多样性，并对生命树中不同群体的发展产生负面影响。然而，农业管理如何影响微生物的多样性及其在土壤中的进化，尤其是在大空间尺度上，仍然未知。在这里，我们通过比较覆盖全国2500 km纬度横断面的天然和农业土壤中的群落，研究了农业土地利用如何影响土壤线虫的生物多样性和潜在的进化事件。在自然生境中，线虫的系统发育和分类学多样性以及物种丰富度与纬度呈驼峰形关系，并在30°N达到峰值，而在农业生境中，这些群落矩阵在所研究的纬度光谱范围内没有变化。同时，农业管理减少了线虫的多样性和丰富度，其影响在亚热带地区更为明显。但是，在整个纬度范围内，农业的进化多样化率要高于自然栖息地。这与土壤有机碳和氮的减少以及线虫群落组成向农业生境中快速发展的分类单元（r策略家）的转移有关。总之，我们的结果表明，由农业经营引起的相对不利的环境状况可以通过丰富快速发展的分类单元来加速线虫的社区一级物种形成速度。