Fig. 1

Sampling site, morphology, divergence distribution of transposable elements, chromosomal contact map and genomic landscape of P. buccinoides. a Morphology of P. buccinoides. b Sampling site of P. buccinoides. P. buccinoides used in the present study were collected from cold spring district. This specie is also common in cold spring vents. The mussels associated with P. buccinoides are also in photo. c Divergence distribution of transposable elements (TEs) in the P. buccinoides genome. De novo prediction. The distribution of sequence divergence rates of TEs as percentages of the genome size is shown. The y-axis shows the percentage of the genome that is annotated as TEs (TE contents). The x-axis shows sequence divergence rate. DNA transposon shown as DNA is indicated with red color, long interspersed nuclear element (LINE) is indicated with orange color, long terminal repeat (LTR) is indicated with yellow color, and short interspersed nuclear element (SINE) is indicated with green color. The percentage of genome and the sequence divergence rate show the cumulative proportion and inconsistency of repeat elements, respectively. d Chromosomal contact map of P. buccinoides. Based on Hi-C data, the chromosomal contact map was built. The contacts between one location and another are referred by blocks. The blocks correspond to 34 Chrs of P. buccinoides. The color reflects the intensity of each contact, and it represents the interaction density from high (red) to low (white) in the plot. In the x-axis and y-axis, each number means the genomic length (Mb). e Diagram and genomic landscape of the gastropod P. buccinoides. Circos atlas represents the Chr information of P. buccinoides. From outside to inside of the concentric circles, (I) Chr length (Mb) and numbers, (II) Density of gene distribution in each 100 kb genomic interval, (III) GC content of 100 kb genomic intervals, and (IV) distribution of genomic repeats density in 100 kb non-overlapping windows. Deep blue color indicates higher repeat density. (V) Major interchromosomal relationships of P. buccinoides Chrs are presented with purple lines, and each line indicates one pair of paralog genes