Geographic distribution and assembly improvements of medaka inbred strains. (A) Geographic distribution of wild medaka populations. The inbred strains Hd-rR, HNI, and HSOK were established from southern and northern Japanese populations and an eastern Korean population, respectively. Divergence times are based on a previous report (Yamahira et al. 2021), and the timing of the duplication/transposition event of (proto-)Dmy is inferred from the distribution of the Dmy-mediated sex-determination system within the genus Oryzias. (B) Assembly statistics on the v3 assemblies compared with the previous v2 assemblies. (C) Complete chromosomes of Hd-rR with annotations of important regions. Mean ONT-UL read depth (0–100×) in 10 kb bins is shown below each chromosome bar.