Insulated Outlier Chromosomes Drive Metabolic and Evolutionary Innovation in Minimal Marine Algae

Ostreococcus, exhibit remarkable ecological success despite possessing small and compact genomes. Here we investigate how these picoeukaryotes maintain adaptive potential within severe genomic constraints, focusing on a unique feature of Mamiellales genomes: two outlier chromosomes containing extensive low-GC regions with distinct genetic characteristics. Using a multi-omics approach combining Hi-C, transcriptomics, genome-wide methylation profiling, and metabolomics, we examined the physical and regulatory insulation of these outlier chromosomes in Ostreococcus and related species.