Gut shuttle service: endozoochory of dispersal-limited soil fauna by gastropods
Numerous important ecosystem functions and services depend on soil biodiversity. However, little is known about the mechanisms which maintain the vast belowground biodiversity and about the filters shaping soil community composition. Yet, biotic interactions like facilitation and dispersal by animals are assumed to play a crucial role, particularly as most soil animal taxa are strongly limited in their active dispersal abilities. Here, we report on a newfound interaction of potentially high ubiquity and importance in soil communities: the endozoochorous dispersal of soil fauna by gastropods. We focus on the dispersal-limited group of oribatid mites, one of the most diverse and abundant soil animal groups. In a field survey in a German riparian forest, 73% of 40 collected slugs (Arion vulgaris) egested a total of 135 oribatid mites, belonging to 35 species. Notably, 70% of the egested mites were alive and survived the gut passage through slugs. Similar results were found for Roman snails (Helix pomatia), indicating the generality of our findings across different gastropod taxa. Complementary laboratory experiments confirmed our field observations, revealing that oribatid mites are, indeed, ingested and egested alive by slugs, and that they are able to independently escape the faeces and colonise new habitats. Our results strongly indicate that gastropods may help soil organisms to disperse within habitats, to overcome dispersal barriers, and to reach short-lived resource patches. Gastropods might even disperse whole multi-trophic micro-ecosystems, a discovery that could have profound implications for our understanding of dispersal mechanisms and the distribution of soil biodiversity.
KeywordsMicro-ecosystem dispersal Oribatid mites Seed dispersal Slugs Soil biodiversity
We are grateful to David Wardle and Wim van der Putten for their comments and suggestions on a previous version of the manuscript and Maria Feustel for her contribution to the surveys and experiments. Franz Horak and Bernhard Klarner identified oribatid and mesostigmatid mites, respectively. Julia Siebert identified protozoa, and Katja Steinauer the plants in the study area. Andrew Barnes improved the manuscript linguistically. MT and NE are supported by the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, funded by the German Research Foundation (DFG; FZT 118). ML is supported by the Max Planck Institute for Biogeochemistry, Jena, Germany and is funded by the German Research Foundation (DFG; FOR 456, FOR 1451–“The Jena Experiment”).
Author contribution statement
MT and NE conceived the study; MT performed the experiments and surveys; MT and ML analyzed the data; MT, ML, and NE wrote the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that there is no conflict of interest.
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