Gene rearrangements in the mitochondrial genome of ten ascaris species

The Ascaridoidea familiy and Heterakoidea familiy are the most common and typical representative of large parasites, which occur in the digestive tract of almost all major vertebrates, including humans. Although our understanding of these parasites’ diversity has expanded by analyses of some mitochondrial genes, there is limited information on these species’ evolutionary rates. Here we determined ten complete mitogenome sequences of five subfamilies of Ascaridoidea and one subfamily of Heterakoidea. The phylogenetic tree divided the Ascaridoidea into six monophyletic major clades, and the divergence time of Heterakoidea familiy and Ascaridoidea familiy can be placed during the early Carboniferous Period (300 ~ 360 Mya). The reconstruction of the ancestral state showed that the gene orders of all species in Ascaridoidea were conserved, and the Heterakoidea had obvious genome rearrangement. The conserved blocks between them were divided into five and the main types are tandem-duplication/random loss (TDRL). These results will help to better understand the gene rearrangements and evolutionary position of ascaris species.