How Do Environmental and Spatial Factors Influence Beta Diversity and Composition of Abundant and Rare Bacterioplankton Communities in Lakes From the Patagonian Plateaus?

Abstract

1. Lakes in the same geographic region often exhibit outstanding differences in environmental features, as is the case in the high-altitude lakes from the basaltic plateaus of Patagonia (Argentina).
2. We analysed bacterial community composition (BCC) at local and regional scales in 37 shallow lakes on two Patagonian plateaus and evaluated the influence of environmental variables and geographic position on community structure.
3. β diversity within each plateau was the key component of regional bacterioplankton diversity. The sum of amplicon sequence variants (ASV) exclusive to each plateau was greater than 50%. Most of the exclusive ASVs corresponded to rare ones from each plateau, whereas abundant ASVs were mostly shared by both plateaus (81%), which indicates a more restricted distribution of rare and higher dispersal of abundant ASVs.
4. The lakes of the Strobel and Buenos Aires plateaus spanned a wide range of environmental conditions, which were associated with the BCC of lakes from both plateaus. Macrophyte cover, fish presence, conductivity, dissolved organic carbon, pH, and altitude were associated with BCC in these lakes. Notably, differences at the phylum and class levels were observed in lakes with contrasting limnological features. Fishless lakes had significantly greater relative abundance of Bacteroidia and Gammaproteobacteria than fish-stocked lakes. Lakes without macrophytes showed significantly higher relative abundances of Cyanobacteria and Planctomycetota than vegetated environments, and, conversely, vegetated lakes exhibited the highest relative abundance of Bacteroidota.
5. Our study shows a strong link between BCC and environmental factors, regardless of their regional or local classifications. Rare bacteria were more strongly associated with spatial factors than total or abundant bacteria, suggesting a limited dispersal capacity. Our findings highlight that variability in environmental conditions influences BCC and determines high β diversity and, consequently, high γ diversity.