Model for IGS homologous satellite repeat development. Ty3-Gypsy type LTR retrotransposon (TRRT) inserted in 18S rDNA might be integrated in the array at the early stage of divergence. The TRRT inserted 18S rDNA persist and increase its copy number through recombination. Duplication of IGS into 25S rDNA seems to be occurred prior to replace type II subrepeat to type I subrepeat. Homogenized satellite repeat may be developed through amplifying type I subrepeat with segmental duplication, but removing neighboring sequences such as 25S rDNA and type II subrepeat.