Comparative mitogenomic analyses provide evolutionary insights into the retrolateral tibial apophysis clade (Araneae: Entelegynae)

Abstract

The retrolateral tibial apophysis (RTA) clade is the largest spider lineage within Araneae. To better understand the diversity and evolution, we newly determined mitogenomes of ten RTA species from six families and performed a comparative mitogenomics analysis by combining them with 40 sequenced RTA mitogenomes available on GenBank. The ten mitogenomes encoded 37 typical mitochondrial genes and included a large non-coding region (putative control region). Nucleotide composition and codon usage were well conserved within the RTA clade, whereas diversity in sequence length and structural features was observed in control region. A reversal of strand asymmetry in nucleotide composition, i.e., negative AT-skews and positive GC-skews, was observed in each RTA species, likely resulting from mitochondrial gene rearrangements. All protein-coding genes were evolving under purifying selection, except for atp8 whose Ka/Ks was larger than 1, possibly due to positive selection or selection relaxation. Both mutation pressure and natural selection might contribute to codon usage bias of 13 protein-coding genes in the RTA lineage. Phylogenetic analyses based on mitogenomic data recovered a family-level phylogeny within the RTA; {[(Oval calamistrum clade, Dionycha), Marronoid clade], Sparassidae}. This study characterized RTA mitogenomes and provided some new insights into the phylogeny and evolution of the RTA clade.

Complete Mitogenomes of Ticks Ixodes acutitarsus and Ixodes ovatus Parasitizing Giant Panda: Deep Insights into the Comparative Mitogenomic and Phylogenetic Relationship of Ixodidae Species

“…The gene arrangement types T1, T2, and T3 were discovered in Prostriata ticks, while T4 and T5 were found in Metastriata ticks ( Figure 7 ). Type T1 was identical to the ancient Arthropoda gene arrangement type found in Limulus polyphemus [ 58 ], which was assumed to be the ancestral type of arthropods and also found in Liphistiidae spiders [ 24 , 34 ], Nuttalliellidae ticks [ 104 , 105 ], and Argasidae ticks [ 59 , 104 ]. The non-Australasian Prostriata ticks had type T1, and almost all Australasian Prostriata ticks had type T2, except that I. fecialis owned type T3; Type T4 was the most common type, occurring in almost all Metastriata ticks, whereas type T5 only occurred in Am.…”

“…danieli OM368292). Such a high proportion of A + T content was also present in other arthropod groups, such as Araneae [ 34 ] and Lepidoptera [ 89 ]. Among 10 genera of the Ixodidae family, Ixodes genus had the largest A + T content variation range from 72.28% to 79.98%, and its average was 77.56%, which was smaller than 79.51% (75.53–80.76%) of the Amblyomma genus, 79.15% (77.20–79.80%) of the Hyalomma genus, 78.24% (76.75–79.30%) of the Dermacentor genus, 78.21% (74.57–80.37%) of the Rhipicephalus genus, and larger than 77.40% (76.40–81.06%) of the Haemaphysalis genus ( Figure 3 A).…”

“…Apparently, the AT-skew of Ixodidae mitogenomes deviated from the general characteristics of metazoan mitogenomes. Negative AT-skews had also been found in the mitogenomes of other taxonomic groups, such as Lepidoptera [ 86 , 89 ] and Araneae [ 34 ]. Such skews towards a particular nucleotide can be related to asymmetric mutational constraints [ 92 ].…”

“…Comparative mitogenomic analyses are of great significance for understanding the biodiversity and evolution, and mitogenomic data can provide efficient phylogenetic signals for a wide variety of animal groups [ 3 , 24 , 33 , 34 ]. The phylogenetic relationships of hard ticks have been studied in depth [ 3 , 4 , 35 , 36 , 37 , 38 , 39 ], but comprehensive comparative mitogenome analyses of them are rarely performed.…”