Trophic interactions with heterotrophic bacteria limit the range of
            <i>Prochlorococcus</i>

Follett, Christopher L.; Dutkiewicz, Stephanie; Ribalet, François; Zakem, Emily; Caron, David A.; Armbrust, E. Virginia; Follows, Michael J.

doi:10.1073/pnas.2110993118

Cited by 43 publications

(54 citation statements)

References 86 publications

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“…Breaking the general trend of correspondence, we predicted high growth rates of low light–adapted ecotypes in the southernmost stations of the transect where the observed population density was low. This might reflect a dominant top-down control of populations in that region ( 28 ) that cannot be captured by the bottom-up growth model. It might also be noted that the AMT-13 transect was conducted during the late boreal summer and austral winter, and mixed layer depths at stations south of 22°S were greater than 140 m (based on the Δσ t = 0.125 kg m −3 criterion).…”

Section: Resultsmentioning

confidence: 99%

Basin-scale biogeography of marine phytoplankton reflects cellular-scale optimization of metabolism and physiology

et al. 2022

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Extensive microdiversity within Prochlorococcus , the most abundant marine cyanobacterium, occurs at scales from a single droplet of seawater to ocean basins. To interpret the structuring role of variations in genetic potential, as well as metabolic and physiological acclimation, we developed a mechanistic constraint-based modeling framework that incorporates the full suite of genes, proteins, metabolic reactions, pigments, and biochemical compositions of 69 sequenced isolates spanning the Prochlorococcus pangenome. Optimizing each strain to the local, observed physical and chemical environment along an Atlantic Ocean transect, we predicted variations in strain-specific patterns of growth rate, metabolic configuration, and physiological state, defining subtle niche subspaces directly attributable to differences in their encoded metabolic potential. Predicted growth rates covaried with observed ecotype abundances, affirming their significance as a measure of fitness and inferring a nonlinear density dependence of mortality. Our study demonstrates the potential to interpret global-scale ecosystem organization in terms of cellular-scale processes.

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Section: Resultsmentioning

confidence: 99%

Basin-scale biogeography of marine phytoplankton reflects cellular-scale optimization of metabolism and physiology

et al. 2022

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“…However, very little is known about the in situ multidimensional regulation of ecotype-level activity and its relationship with the distribution of Prochlorococcus or SAR11. In fact, evidence suggests that the relationship between activity and distribution can be decoupled by trophic interactions [ 11 , 12 ]. Inferences into metabolic activity may both provide an added dimension to microbial niche dynamics and reveal the linkages between genome content and taxa-specific functional roles.…”

Section: Introductionmentioning

confidence: 99%

Basin-scale biogeography of Prochlorococcus and SAR11 ecotype replication

et al. 2022

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Establishing links between microbial diversity and environmental processes requires resolving the high degree of functional variation among closely related lineages or ecotypes. Here, we implement and validate an improved metagenomic approach that estimates the spatial biogeography and environmental regulation of ecotype-specific replication patterns (RObs) across ocean regions. A total of 719 metagenomes were analyzed from meridional Bio-GO-SHIP sections in the Atlantic and Indian Ocean. Accounting for sequencing bias and anchoring replication estimates in genome structure were critical for identifying physiologically relevant biological signals. For example, ecotypes within the dominant marine cyanobacteria Prochlorococcus exhibited distinct diel cycles in RObs that peaked between 19:00–22:00. Additionally, both Prochlorococcus ecotypes and ecotypes within the highly abundant heterotroph Pelagibacter (SAR11) demonstrated systematic biogeographies in RObs that differed from spatial patterns in relative abundance. Finally, RObs was significantly regulated by nutrient stress and temperature, and explained by differences in the genomic potential for nutrient transport, energy production, cell wall structure, and replication. Our results suggest that our new approach to estimating replication is reflective of gross population growth. Moreover, this work reveals that the interaction between adaptation and environmental change drives systematic variability in replication patterns across ocean basins that is ecotype-specific, adding an activity-based dimension to our understanding of microbial niche space.

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“…However, there might be other processes that can potentially affect the amplitude of diel nutrient cycles. These might include diel patterns in nutrient competition between phytoplankton and bacteria (Follett et al, 2022; Kirchman et al, 1994) or diel variations in remineralization rates (Graham et al, 2000) that are not included in the present model.…”

Section: Discussionmentioning

confidence: 99%

Diel light cycles affect phytoplankton competition in the global ocean

Tsakalakis

Follows

Dutkiewicz

et al. 2022

Global Ecol. Biogeogr.

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Aim: Light, essential for photosynthesis, is present in two periodic cycles in nature: seasonal and diel. Although seasonality of light is typically resolved in ocean biogeochemical-ecosystem models because of its significance for seasonal succession and biogeography of phytoplankton, the diel light cycle is generally not resolved.The goal of this study is to demonstrate the impact of diel light cycles on phytoplankton competition and biogeography in the global ocean. Location: Global ocean. Major taxa studied: Phytoplankton. Methods: We use a three-dimensional global ocean model and compare simulations of high temporal resolution with and without diel light cycles. The model simulates 15 phytoplankton types with different cell sizes, encompassing two broad ecological strategies: small cells with high nutrient affinity (gleaners) and larger cells with high maximal growth rate (opportunists). Both are grazed by zooplankton and limited by nitrogen, phosphorus and iron.Results: Simulations show that diel cycles of light induce diel cycles in limiting nutrients in the global ocean. Diel nutrient cycles are associated with higher concentrations of limiting nutrients, by 100% at low latitudes (−40° to 40°), a process that increases the relative abundance of opportunists over gleaners. Size classes with the highest maximal growth rates from both gleaner and opportunist groups are favoured by diel light cycles. This mechanism weakens as latitude increases, because the effects of the seasonal cycle dominate over those of the diel cycle. Main conclusions:Understanding the mechanisms that govern phytoplankton biogeography is crucial for predicting ocean ecosystem functioning and biogeochemical cycles. We show that the diel light cycle has a significant impact on phytoplankton competition and biogeography, indicating the need for understanding the role of diel processes in shaping macroecological patterns in the global ocean.

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Trophic interactions with heterotrophic bacteria limit the range of Prochlorococcus

Cited by 43 publications

References 86 publications

Basin-scale biogeography of marine phytoplankton reflects cellular-scale optimization of metabolism and physiology

Basin-scale biogeography of marine phytoplankton reflects cellular-scale optimization of metabolism and physiology

Basin-scale biogeography of Prochlorococcus and SAR11 ecotype replication

Diel light cycles affect phytoplankton competition in the global ocean

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