Fig. 3

Chromosome rearrangement is associated with LTR insertion. A The species tree of Pieridae. B The synteny plots of Pieridae. We found that some species of Pieridae experienced extensive chromosomal rearrangements, such as P. napi, Pieris brassicae, Pieris rapae, and Aporia crataegi. Meanwhile, the synteny within the genus Pieris is highly conserved. C LTRs are enriched within C. croceus and P. napi synteny breakpoint regions in the P. napi genome. Histograms show the distribution of TE counts (by class) in 10,000 randomized sets of chromosomal regions with the same size distribution as observed in C. croceus and P. napi synteny breakpoint regions. Red lines indicate observed values for each TE class within autosomal synteny breakpoint regions, which shows that long terminal repeat retrotransposons (C LTR) are significantly enriched in the breakpoint regions. The DNA transposons (D DNA), unidentified transposons (E Unknown), rolling-circle Helitron transposons (F RC), and long and short interspersed nuclear elements (G LINE and H SINE) are not enriched. I The time of the burst of LTRs on P. napi genome is later than the divergence time between P. napi and C. croceus. Histograms showing the age distribution of LTRs located on the P. napi genome. Red lines indicate the divergence time between P. napi and C. croceus. The y-axis shows the LTR content (kb) of the P. napi genome