Comparative analysis of miRNAs
The evolutionary divergence of miRNAs may contribute to the diversification of species (Plasterk et al., 2006). Liu et al. (2020) analysed the miRNA data of FCDK based on genome and small RNA (sRNA) data from mixed embryos, juveniles and adults (GenBank accession No. SRP132383). In this study, we de novo sequenced sRNAs of mixed individual specimens of FCSH, including living embryos, juveniles and adults in different developmental stages (GenBank accession No. SRP308782). Based on the sRNA data and chromosomal-level genome assemblies of FCDK and FCSH, known miRNAs with homologous genes in the miRBase 21 database (Kozomara & Griffiths-Jones, 2014) were identified, and novel miRNAs were predicted according to the procedure described in Liu et al. (2020). By mapping miRNA precursors to the corresponding genome using MapChart (Voorrips, 2002), the locations of miRNAs were recorded and compared between FCDK and FCSH. The miRNA nomenclature followed previous studies (Fromm et al., 2015; Liu et al., 2020). The prefix MIR- indicates family names, and Mir- indicates gene names. Duplicated paralogous genes were identified with the letter ā€˜p’ and a number.