Extending conservation to include Earth's microbiome

The diversity of ignorance and the ignorance of diversity: origins and implications of "shadow diversity" for conservation biology and extinction

Biodiversity shortfalls and taxonomic bias can lead to inaccurate assessment of conservation priorities. Previous literature has begun to explore practical reasons why some species are discovered sooner or are better researched than others. However, the deeper socio-cultural causes for undiscovered and neglected biodiversity, and the value of collectively analysing species at risk of unrecorded, or "dark", extinction, are yet to be fully examined. Here, we argue that a new label (we propose "shadow diversity") is needed to shift our perspective from biodiversity shortfalls to living, albeit unknown, species. We suggest this linguistic shift imparts intrinsic value to these species, beyond scientific gaze and cultural systems. We review research on undiscovered, undetected and hidden biodiversity in the fields of conservation biology, macroecology and genetics. Drawing on philosophy, geography, history and sociology, we demonstrate that a range of socio-cultural factors (funding, education and historical bias) combine with traditional, practical impediments to limit species discovery and detection. We propose using a spectrum of shadow diversity which enables a complex, non-binary and comprehensive approach to biodiversity unknowns. Shadow diversity holds exciting potential as a tool to increase awareness, appreciation and support for the conservation of traditionally less studied wildlife species and sites, from soil microbes to less charismatic habitat fragments. We advocate for a shift in how the conservation community and wider public see biodiversity and an increase in popular support for conserving a wider range of life forms. Most importantly, shadow diversity provides appropriate language and conceptual frameworks to discuss species absent from conservation assessment and at potential risk of dark extinction.

Refocusing the microbial rare biosphere concept through a functional lens

The influential concept of the rare biosphere in microbial ecology has underscored the importance of taxa occurring at low abundances yet potentially playing key roles in communities and ecosystems. Here, we refocus the concept of rare biosphere through a functional trait-based lens and provide a framework to characterize microbial functional rarity, a combination of numerical scarcity across space or time and trait distinctiveness. We demonstrate how this novel interpretation of the rare biosphere, rooted in microbial functions, can enhance our mechanistic understanding of microbial community structure. It also sheds light on functionally distinct microbes, directing conservation efforts towards taxa harboring rare yet ecologically crucial functions.

Effects of increasing soil moisture on Antarctic desert microbial ecosystems

Overgeneralization and a lack of baseline data for microorganisms in high-latitude environments have restricted the understanding of the microbial response to climate change, which is needed to establish Antarctic conservation frameworks. To bridge this gap, we examined over 17,000 sequence variants of bacteria and microeukarya across the hyperarid Vestfold Hills and Windmill Islands regions of eastern Antarctica. Using an extended gradient forest model, we quantified multispecies response to variations along 79 edaphic gradients to explore the effects of change and wind-driven dispersal on community dynamics under projected warming trends. We also analyzed a second set of soil community data from the Windmill Islands to test our predictions of major environmental tipping points. Soil moisture was the most robust predictor for shaping the regional soil microbiome; the highest rates of compositional turnover occurred at 10-12% soil moisture threshold for photoautotrophs, such as Cyanobacteria, Chlorophyta, and Ochrophyta. Dust profiles revealed a high dispersal propensity for Chlamydomonas, a microalga, and higher biomass was detected at trafficked research stations. This could signal the potential for algal blooms and increased nonendemic species dispersal as human activities increase in the region. Predicted increases in moisture availability on the Windmill Islands were accompanied by high photoautotroph abundances. Abundances of rare oligotrophic taxa, such as Eremiobacterota and Candidatus Dormibacterota, which play a crucial role in atmospheric chemosynthesis, declined over time. That photosynthetic taxa increased as soil moisture increased under a warming scenario suggests the potential for competition between primary production strategies and thus a more biotically driven ecosystem should the climate become milder. Better understanding of environmental triggers will aid conservation efforts, and it is crucial that long-term monitoring of our study sites be established for the protection of Antarctic desert ecosystems. Furthermore, the successful implementation of an improved gradient forest model presents an exciting opportunity to broaden its use on microbial systems globally.

Disentangling microbial networks across pelagic zones in the tropical and subtropical global ocean

Microbial interactions are vital in maintaining ocean ecosystem function, yet their dynamic nature and complexity remain largely unexplored. Here, we use association networks to investigate possible ecological interactions in the marine microbiome among archaea, bacteria, and picoeukaryotes throughout different depths and geographical regions of the tropical and subtropical global ocean. Our findings reveal that potential microbial interactions change with depth and geographical scale, exhibiting highly heterogeneous distributions. A few potential interactions were global, meaning they occurred across regions at the same depth, while 11-36% were regional within specific depths. The bathypelagic zone had the lowest proportion of global associations, and regional associations increased with depth. Moreover, we observed that most surface water associations do not persist in deeper ocean layers despite microbial vertical dispersal. Our work contributes to a deeper understanding of the tropical and subtropical global ocean interactome, which is essential for addressing the challenges posed by global change.