Comparative genome analysis reveals larger genome sizes and higher gene numbers in C. nigoni strains relative to C. briggsae strains. (Left) Phylogenetic relationships of eight C. nigoni and six C. briggsae wild isolates, along with their corresponding reference strains, namely, JU1421 and AF16 (highlighted in bold), respectively. The phylogenetic tree was constructed using concatenated protein sequences of orthologous genes based on the maximum likelihood method. (Right) Comparative genomic features between interspecific and intraspecific strains, including genome sizes (A), gene numbers (B), repeat content as a percentage of the genome (C), proportions of repeat types among total repeats (D), gene length distributions (E), and coding DNA sequence (CDS) length distributions (F). (Retro TE) Retrotransposon, (RC TE) rolling circle transposon.