Unexpected species diversity in the understanding of selenium- containing soil invertebrates

Yutangba, situated in Enshi City, Hubei Province, is globally noted its high selenium (Se) content. Soil invertebrates are essential to the functionality and services of terrestrial ecosystems, yet their community composition in this region remains under-explored. This study utilized environmental DNA metabarcoding to investigate the interrelations among environmental factors, soil invertebrate diversity, and community characteristics concerning soil Se content, pH, and moisture content in the region. Environmental factors such as Se concentration, water content, and pH were strongly associated with the alpha and beta diversity of soil invertebrates in Se-rich areas, affecting their distribution and abundance. Among these, Se notably emerges as the primary regulatory factor influencing soil invertebrate diversity. The acidic soil pH, along with moisture, plays a fine-tuning role in regulating species diversity by directly or indirectly influencing the availability and bioavailability of Se, impacting the species richness and community composition. Unexpectedly, certain species, such as the Formicidae (ants, e.g., Odontomachus troglodytes ), the Noctuidae (e.g., Diarsia rosaria ), and the annelid Haplotaxida Perionyx excavates , exhibit a strong positive association with Se, indicating a high level of Se tolerance among the native species. This novel perspective reveals the complex role of Se in soil ecosystems, emphasizing the necessity of understanding its ecological functions and potential implications for ecosystem health and stability.