Hox gene cluster identification
Sequences of the known Hox genes were downloaded from the SwissProt database and used for Hox gene annotation in other species. Specifically, the downloaded sequences were aligned to the genome assembly using BLAST software (tblastn, v2.6.0) (Altschul et al. 1990) with an e-value of 1e-10. The lowest e-value of the annotation result was selected for the final annotation of each gene.