Fig. 4

Inverse relationship between the number of 5′ cassette tandem duplicates and gene duplicates. a, b The number of 5′ cassette duplicates correlated inversely with the number of gene duplicates in sDscamα (a) and sDscamβ (b) in Chelicerata species. c, d Comparison of the number of 5′ cassette (c) and gene duplicates (d) between sDscamα and sDscamβ. Data are expressed as mean ± standard deviation (SD). e−i The number of 5′ cassette tandem duplicates correlated inversely with the duplicate size. This reverse relationship is conserved in M. occidentalis (e), I. scapularis (f), M. martensii (g), S. mimosarum (h), and L. polyphemus (i). j Comparison of the size of cassette repeats in sDscamα and sDscamβ. k, l The size of the cassette repeats correlated with the genome size of Chelicerata in sDscamα (k) and sDscamβ (l). The number of 5′ cassette tandem duplicates is indicated by the circle size. m Intron loss occurred independently in the sDscamβ1 and sDscamβ2 genes of M. occidentalis. The introns are represented with lines (not drawn to scale). Red circles indicate the intron loss, and the arrows indicate the transcription start sites