How Big Is Big? (Dr. Luo's lab new publication)

Our study in [Journal Name] challenges assumptions about effective population sizes (N_e) in abundant but genome-reduced marine bacteria like Prochlorococcus and CHUG. Despite their vast census numbers in ocean surface waters, genomic analyses reveal their N_e is 10× smaller than in less abundant, large-genome lineages (e.g., Ruegeria, Vibrio), suggesting stronger genetic drift limits adaptive potential. This paradox—where ecological success contrasts with constrained evolutionary flexibility—highlights the need to disentangle ancient genome reduction’s legacy from modern population dynamics. By pioneering methods to infer mutation rates in these lineages, we provide critical insights into how drift vs. selection shapes microbial evolution in the ocean. Our work redefines frameworks for understanding the genomic resilience of Earth’s most abundant photosynthetic organisms.

Read the full study here: https://doi.org/10.1146/annurev-marine-050823-104415

(Luo H. W. How Big Is Big? The Effective Population Size of Marine Bacteria. Annual Review of Marine Science. Vol. 17: 537-560 (2025). https://doi.org/10.1146/annurev-marine-050823-104415)