Fundamental differences in diversity and genomic population structure between Atlantic and Pacific Prochlorococcus

Area of Science:

• Marine microbiology
• Oceanography
• Genomics

Background:

• Prochlorococcus is a globally abundant marine cyanobacterium.
• Distinct biogeochemical regimes exist in the Atlantic and Pacific Oceans.
• Atlantic Prochlorococcus populations show high genomic diversity with numerous coexisting subpopulations.

Purpose of the Study:

• To investigate if oceanographic differences between the Atlantic and Pacific impact Prochlorococcus diversity and genomic composition.
• To compare Prochlorococcus populations from the Bermuda Atlantic Time Series (BATS) and Station ALOHA (Hawaii).

Main Methods:

• Large-scale single-cell genomics was employed.
• Cell-by-cell genomic composition of wild Prochlorococcus populations was compared between BATS and Station ALOHA.

Main Results:

• Fundamental differences in diversity and genomic structure were observed between Atlantic and Pacific Prochlorococcus.
• Pacific populations are more diverse, with more subpopulations and fewer dominant ones compared to Atlantic populations.
• Prochlorococcus populations from each ocean possess distinct genomic backbones, suggesting ocean-specific micro-niches and non-overlapping subpopulations.

Conclusions:

• Geographic separation and differential selection pressures significantly shape Prochlorococcus populations in the Atlantic and Pacific.
• Phylogenetically related strains share ocean-associated nutrient acquisition genes, indicating adaptation to distinct environmental conditions.
• Ocean-specific selection and geographic isolation are key drivers of Prochlorococcus population structure.