Comparison of satDNAs in the centromeric regions of the sibling species T. freemani and T. castaneum. (A) Proposed origin of the major satDNAs TfSat01 and TCAST from an ancestral satellite DNA and a transposon-like element in T. freemani and T. castaneum, respectively. Blue and red boxes show the resulting repeats in each species. (B) Schematic of long-range organization of the species-specific major satDNAs TfSat01 and TCAST, intermingled with orthologous minor satDNAs TfSat03 and Cast7, respectively, in the centromeric regions of T. freemani and T. castaneum. (C) PCA clustering of the orthologous Cast7, TfSat03, and TfSat04 repeats. The analysis included 1000 randomly selected Cast7 monomers from the TcasONT assembly, together with subunits A, B, and C from 1000 randomly selected TfSat03 repeats and all 159 TfSat04 monomers annotated in the Tfree1.0 assembly. Dots represent individual sequences, color-coded by repeat type.