Landscape connectivity for the invisibles

Abstract

Because of land use changes, a worldwide decrease in biodiversity is underway, mostly driven by habitat degradation and fragmentation. Increasing landscape connectivity (i.e. the degree to which the landscape facilitates movement between habitat patches) has been proposed as a key landscape-level strategy to counterbalance the negative effects of habitat fragmentation. A robust theoretical and methodological framework has been developed for the concept of connectivity, and an increasing body of empirical evidence supports the relevance of connectivity for biodiversity. However, the framework was built ignoring species that represent the dominant proportion of biodiversity on earth: microorganisms. The extent to which the existing conceptual and methodological frameworks on connectivity can be applied to microorganisms remain unknown. We reviewed existing evidence and analyzed methods to test the influence of connectivity on microorganisms. We included all types of microorganisms, from symbiotic to pathogenic and free-living microorganisms, across all ecosystems. We describe the effect of connectivity on microorganism populations and communities, and identify the limitations and large gaps in current knowledge. Microorganisms can differ from macroorganisms in their response to connectivity due to short (distance less than a meter) dispersal distance of some groups, longer time lag of microorganisms response (possibly accompanied by evolutionary processes) and host association. The latter relies on tight interactions and feedback effects that drive microbial-landscape relationships and lead to possible coadaptation processes. Incorporating the connectivity concept in microbial community assembly rules to preserve the diversity of microbial communities and the ecosystem services they provide could be a crucial step forward in the face of pressing global changes.

Landscape structure is a key driver of soil protist diversity in meadows in the Swiss Alps

“…While the present study and several other recent works (Mennicken et al 2020;Mony et al 2021Mony et al , 2022 provide a strong basis to further develop the field of microbial landscape ecology, much remains to be done. One of the most important questions arising from our work is the actual rate of dispersal (excess or limitations) of protists and microbes in general from surrounding habitats (Frey 2015).…”

“…Despite their potential, landscape ecology approaches applied to microbial communities remain scarce (Mony et al 2020(Mony et al , 2022, mostly due to the difficulty to observe these organisms. Progress in DNA-based characterization of community composition now makes it easier to conduct landscape-scale surveys of microbial diversity (Kibblewhite et al 2008).…”

Ecological corridors homogenize plant root endospheric mycobiota

“…Such time-lag effects in response to landscape structure are referred to as a colonization credit and have been repeatedly demonstrated in the case of macroorganisms (Kuussaari et al , 2009). There have only been a few demonstrations of such processes in microorganisms especially in response to habitat connectivity (Mony et al , 2022), probably because of the limited number of studies based on time-series analysis of microbial composition. The present work demonstrates the importance of analyzing temporal dynamics in microbial response to host landscapes.…”

“…An original aspect of this study is that we detected such corridor effects at the community level despite the wide range of modes of dispersal. Community-wide assessment of corridor effects is quite recent in landscape ecology for macroorganisms (Uroy et al , 2019), while it is one of the very first pieces of evidence for microorganisms (see Mony et al, 2022 for a review on habitat corridor studies for microbes). Because such effects are demonstrated at the community level, these results also demonstrate that most fungi are limited to short spatial scales for their dispersal.…”

Spatial Habitat Structure Assembles Willow-Dependent Communities across the Primary Successional Watersheds of Mount St. Helens

“…Thus, the ability of primary successional tree communities to influence connectivity is reliant on where water is found on the landscape, how much water is available, and how these characteristics change over time [41][42][43][44]. The connectivity of these tree communities, and by proxy the connectivity of water availability, should then be directly related to associated arthropod and microbial communities that establish on trees post-disturbance [45][46].…”