Solar salterns as model systems to study the units of bacterial diversity that matter for ecosystem functioning

Microbial communities often harbor overwhelming species and gene diversity, making it challenging to determine the important units to study this diversity. We argue that the reduced, and thus tractable, microbial diversity of manmade salterns provides an ideal system to advance this cornerstone issue. We review recent time-series genomic and metagenomic studies of the saltern-dominating bacterial and archaeal taxa to show that these taxa form persistent, sequence-discrete, species-like populations. While these populations harbor extensive intra-population gene diversity, even within a single saltern site, only a small minority of these genes appear to be functionally important during environmental perturbations. We outline an approach to detect and track such populations and their ecologically important genes that should be broadly applicable.
This work was partly funded by the US National Science Foundation, awards #1831582 and #1759831 (to KTK), and by the projects CLG2015_66686-C3-1-P, PGC2018-096956-B-C41 and RTC-2017-6405-1 of the Spanish Ministry of Science, Innovation and Universities (to RRM), which were also supported with European Regional Development Fund (FEDER) funds. RRM acknowledges the financial support of the sabbatical stay at Georgia Tech by the grant PRX18/00048 also from the Spanish Ministry of Science, Innovation and Universities.