Genetic Diversity and Population Dynamics in Marine Phytoplankton

Marine phytoplankton, comprising diverse lineages of microalgae, form the foundation of oceanic food webs and drive global biogeochemical cycles through primary production and carbon sequestration. Genetic diversity within and between phytoplankton populations underpins their capacity to adapt to rapid environmental change, including ocean warming, acidification and nutrient shifts. Variability in allele frequencies arises through natural selection, genetic drift and dispersal, shaping population structure on spatial and temporal scales. Seasonal blooms often represent pulses of genetic diversification, followed by reductions in diversity during quiescent phases and resting‐stage formation. Patterns of connectivity via ocean currents influence gene flow, determining the extent of local adaptation and the potential for rescue by immigrant genotypes. High‐resolution molecular tools—ranging from microsatellite markers to genome‐wide approaches—have revealed cryptic subdivisions within morphospecies, recurrent hybridisation events and trade-offs among traits such as nutrient affinity and toxin production. Understanding these dynamics is critical to predicting ecosystem responses to climate perturbations and to designing management strategies, such as the placement of marine protected areas or mitigation of harmful algal blooms. Emerging insights establish that both ecological processes and evolutionary mechanisms operate on overlapping timescales, so that diversity and dispersal collectively shape the resilience and functioning of marine phytoplankton communities.

Research from Nature Portfolio

Recent studies have advanced our understanding of how physical transport structures connectivity and diversity among phytoplankton communities. One investigation in a frontal system of the North Sea employed coupled species abundance data and an Eulerian connectivity tracer to demonstrate that water‐mass exchange, rather than mere geographic proximity, best predicts community composition. This approach revealed timescales of dispersal barriers and suggested a framework for optimising the design of conservation zones. A foundational analysis at the global scale used Lagrangian particle tracking and network theory to quantify the decadal timescales over which surface currents connect ocean patches. It established that the average fastest pathway between two random surface locations is under ten years, implying that ocean currents may facilitate rapid mixing of resilient phytoplankton types and potentially allow communities to keep pace with climate‐driven habitat changes.

Genetic Diversity and Population Dynamics in Marine Phytoplankton publication trend

The graph below shows the total number of articles in genetic diversity and population dynamics in marine phytoplankton across all publications each year (not limited to Nature Index journals).

Technical terms

Genetic drift: Random fluctuations in allele frequencies within a population due to chance events rather than selection.

Allele frequency: The proportion of a specific variant of a gene within a population’s gene pool.

Connectivity tracer: A computational tool that tracks the exchange of water masses to infer dispersal pathways and barriers for plankton.

Lagrangian particle tracking: A modelling technique that simulates the trajectories of water parcels (or virtual particles) to study ocean transport.

Intraspecific variation: Genetic or phenotypic differences among individuals within the same species or population.

References

1. How does evolution work in superabundant microbes?. Trends in Microbiology (2024).
2. Phytoplankton diversity explained by connectivity across a mesoscale frontal system in the open ocean. Scientific Reports (2023).
3. The timescales of global surface-ocean connectivity. Nature Communications (2016).
4. Intraspecific trait variation and trade‐offs within and across populations of a toxic dinoflagellate. Ecology Letters (2018).
5. Strain-specific transcriptional responses overshadow salinity effects in a marine diatom sampled along the Baltic Sea salinity cline. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2022).