Title

Higher contribution of globally rare bacterial taxa reflects environmental transitions across the surface ocean

Document Type

Journal Article

Publication Title

Molecular Ecology

ISSN

1365-294X

Volume

28

Issue

8

First Page

1930

Last Page

1945

PubMed ID

30663830

Publisher

John Wiley & Sons

School

Centre for Marine Ecosystems Research

Funders

Funding information available at: https://doi.org/10.1111/mec.15026

Comments

Originally published as: Ruiz‐González, C., Logares, R., Sebastián, M., Mestre, M., Rodríguez‐Martínez, R., Galí, M., ... Gasol, J. M. (2019). Higher contribution of globally rare bacterial taxa reflects environmental transitions across the surface ocean. Molecular Ecology, 28(8), 1930-1945. Original publication available here

Abstract

Microbial taxa range from being ubiquitous and abundant across space to extremely rare and endemic, depending on their ecophysiology and on different processes acting locally or regionally. However, little is known about how cosmopolitan or rare taxa combine to constitute communities and whether environmental variations promote changes in their relative abundances. Here we identified the Spatial Abundance Distribution (SpAD) of individual prokaryotic taxa (16S rDNA-defined Operational Taxonomic Units, OTUs) across 108 globally-distributed surface ocean stations. We grouped taxa based on their SpAD shape ("normal-like"- abundant and ubiquitous; "logistic"- globally rare, present in few sites; and "bimodal"- abundant only in certain oceanic regions), and investigated how the abundance of these three categories relates to environmental gradients. Most surface assemblages were numerically dominated by a few cosmopolitan "normal-like" OTUs, yet there was a gradual shift towards assemblages dominated by "logistic" taxa in specific areas with productivity and temperature differing the most from the average conditions in the sampled stations. When we performed the SpAD categorization including additional habitats (deeper layers and particles of varying sizes), the SpAD of many OTUs changed towards fewer "normal-like" shapes, and OTUs categorized as globally rare in the surface ocean became abundant. This suggests that understanding the mechanisms behind microbial rarity and dominance requires expanding the context of study beyond local communities and single habitats. We show that marine bacterial communities comprise taxa displaying a continuum of SpADs, and that variations in their abundances can be linked to habitat transitions or barriers that delimit the distribution of community members.

DOI

10.1111/mec.15026

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