MADRID, 21 (EUROPA PRESS)
An international study with the participation of the Spanish National Research Council (CSIC) demonstrates that changes in land use favor the expansion of protists—single-celled microorganisms that play an important role in microbial food webs—from temperate regions to subtropical zones, beyond their native range.
This shift alters natural ecological patterns and contributes to the loss of soil diversity on a continental scale.
Land-use changes are altering the distribution patterns of a wide range of species. However, the impacts of these changes on the distribution of soil microbiota and their consequences for large-scale biodiversity patterns are unknown.
Research in which the CSIC participates shows that human land-use practices facilitate the expansion of the range of generalist soil protist taxa from temperate to subtropical regions.
This transregional flow of species contributes to biological homogenization at the continental scale. Our findings indicate that land-use changes create potential hotspots for microbial invasions, particularly in subtropical and tropical regions, highlighting the fact that understudied regions are likely to be strongly affected by biological homogenization related to the introduction of exotic species.
Land-use changes are transforming the distribution of aboveground species worldwide. However, the impact of these changes on the distribution of soil organisms remains poorly understood. In particular, there is no mechanistic understanding of the environmental factors that transform the distribution of soil microbiota in response to global biological homogenization.
In this study, metabarcoding was used to investigate the biogeography of protists and their relationships with prey and hosts in three human-dominated ecosystem types: croplands, residential areas, and parks, along with natural forests, in subtropical and temperate climatic regions of China. Human-driven land-use systems were found to extend the distribution range of habitat-generalist protists compared to forests.
This human-facilitated expansion of protists was highly directional and primarily driven by the range expansion of soil taxa from temperate to subtropical regions. In summary, increases in soil pH associated with human-driven land uses mitigate the natural acidity barrier typically found in subtropical ecosystems, facilitating the range expansion of protist species from temperate to subtropical regions.
However, in temperate regions, the northward expansion of subtropical species is likely restricted by a more arid climate with even higher soil pH. The interregional spread of soil protists was more pronounced in phagotrophs than in phototrophs and parasites, reflecting codispersal of phagotrophic protists and microbial prey (especially bacteria) related to close predator-prey specialization or similar responses to environmental changes.
The researchers' findings indicate that land-use changes create hotspots for potential microbial invasions, especially in subtropical and tropical regions, highlighting the potential for understudied regions to be severely affected by biological homogenization associated with the introduction of exotic species.
