| Glyptothorax zainaensis and Glyptothorax cavia belong to Glyptothorax, Sisoridae, Siluriformes, Osteichthyes; Pareuchiloglanis gongshanensis belongs to Pareuchiloglanis Glyptothorax, Sisoridae, Osteichthyes. In this study, we sequenced the whole mitochondrial genomes of the three Sisoridae fish, and annotated them in detail, then Submitted to NCBI database. We downloaded 12 species of Sisoridae mitochondrial genome which were published in GenBank, in combination with the mitochondrial genetic information of the three species in this study. We infer the phylogenetic relationships among these families from the perspective of the Cyt b and COX1 genes, and using BEAST to estimate the time span of genetic differentiation of Sisoridae fishes. The main conclusions were as follows:1. The complete mitochondrial genome of Glyptothorax zainaensis was sequenced to be 16537 bp in length, the Glyptothorax cavia was 16529 bp and the Pareuchiloglanis gongshanensis was 16588 bp. The sequence similarity between Glyptothorax zainaensis and Glyptothorax cavia, Glyptothorax zainaensis and Pareuchiloglanis gongshanensis, Glyptothorax cavia and Pareuchiloglanis gongshanensis were 93%, 81%, 81%, respectively. Their genetic make up and arrangement were similar, and the nucleotide composition in three species mt DNA showed A+T bias, the overall A+T% content account 57.2% in Glyptothorax zainaensis mtDNA, 56.8% in Glyptothorax cavia and 54.8% in Pareuchiloglanis gongshanensis. There are also several intergenic region and gene overlapping in the three species mt DNA.2. Glyptothorax zainaensis and the Glyptothorax cavia have the same initiation codons and termination codons which were similar with Pareuchiloglanis gongshanensis, they usually use ATG and GTG as start codons. ND2, ND4, COX2, COX3, ND3 and Cyt b used the incomplete termination codon T or TA, the other PCGs were terminated with the typical TAA or TAG.The number of the codons of both three Sisoridae fishes mtDNA that RSCU>1 is more than 30 in each species and these codons usually prefer to end with A or T base. All three Sisoridae fishes tRNA genes formed typical clover-leaf structure expect tRNA-Ser and most of the tRNA anticodon is GNN and TNN, the wobble nucleotide is T or G. There are several gene mismatch(mainly U-G mismatch) in their tRNA gene sequence and the most of which take place on the TΨC arm or the DHU arm.3. In this study, we support that Glyptosternon, Glaridoglanis and Exostoma were the primitive taxas of the Glyptosternoid fishes and the Glaridoglanis is the original. The phylogenetic position of Exostoma has always been controversial, but in this study, Exostoma formed a sistergroup with Glaridoglanis and this monophyletic group formed a sistergroup with Glyptosternon. Neither Pareuchiloglanis nor Glyptothorax was monophyly and Glyptothorax formed a sistergroup with Gagata.4.Chinese Sisoridae were found to originate in the Late Miocene(c. 9.87 Ma), the Glyptosternoids later in the Late Miocene(c. 8.93 Mya), the genera differentiation is mainly in the late pliocene to pleistocene(about 0.2 ~ 4.0 Mya), these results also show that explosive speciation of the specialized Glyptosternoids such as Pareuchiloglanis, Pseudexostoma, Oreoglanis and Euchiloglanis occurred during this period.The differentiation time of Glyptothorax-like fishes is mainly in 4.64 after Mya.As the rapid uplift of the qinghai-tibet plateau is around 3.6 Mya and at its peak in 3.0 Mya, meanwhile the explosive speciation of the specialized Glyptosternoids and sequential formation of the water system such as the Jinshajiang river, the Nujiang river, the Lancangjiang river and the Yuanjiang river occuered during this period, and then spread to the downstream of the Nujiang river, the Lancangjiang river, the Yarlung zangbo river and the Irrawaddy river.These results suggest that the Glyptosternoids’ species differentiation have inseparable relationship with the uplift of the qinghai-tibet plateau and the formation of the water system. |
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