Fig. 6

LTR retrotransposons, female-specific genes, and palindromes. a Each vertical line with a wedge on top represents each of the 13 TEs identified in the palindromic region by LTRharvest. The height of each line indicates the number of estimated nucleotide substitutions in the two LTRs (transposons a-h), and an approximation of the insertion time based on the mutation rate in P. tremula [29]. b Colored boxes represent putative chromosomal origins of genes in the palindrome. Dark red, Chr19, cyan, Chr17. Blue boxes represent genes with paralogs on the Z chromosome. c The positions of 13 LTRs (shaded boxes). Hatched boxes represent incomplete duplications derived from Ltr-p2-b3/b4. d Exon positions and orientations, represented by colored arrows. e Schematic representation of female-specific palindromes. The box with a star represents a homologous region derived from part of one of the arms (preARM). Directions of arrows indicate the relative orientations of the four arms