Molecular evolution and phylogenetic utility of the internal transcribed spacer 2 (ITS2) in Calyptratae (Diptera: Brachycera).
The resolution potential of internal transcribed spacer 2 (ITS2) at deeper levels remains controversial. In this study, 105 ITS2 sequences of 55 species in Calyptratae were analyzed to examine the phylogenetic utility of the spacer above the subfamily level and to further understand its evolutionary characteristics. We predicted the secondary structure of each sequence using the minimum-energy algorithm and constructed two data matrixes for phylogenetic analysis. The ITS2 regions of Calyptratae display strong A-T bias and slight variation in length. The tandem and dispersed repeats embedded in the spacers possibly resulted from replication slippage or transposition. Most foldings conformed to the four-domain model. Sequence comparison in combination with the secondary structures revealed six conserved motifs. Covariation analysis from the conserved motifs indicated that the secondary structure restrains the sequence evolution of the spacer. The deep-level phylogeny derived from the ITS2 data largely agreed with the phylogenetic hypotheses from morphologic and other molecular evidence. Our analyses suggest that the accordant resolutions generated from different analyses can be used to infer deep-level phylogenetic relations.
Song
Zhong-kui
ZK
Southwest Forestry University, Kunming, 650224, People's Republic of China. songsir2003@yahoo.com.cn
Wang
Xun-zhang
XZ
Liang
Ge-qiu
GQ
D000465:Algorithms; D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D017124:Conserved Sequence; D021903:DNA, Ribosomal Spacer / Q000737:chemistry* / Q000235:genetics*; D004175:Diptera / Q000145:classification / Q000235:genetics*; D019143:Evolution, Molecular; D049810:Genetic Speciation; D020071:Interspersed Repetitive Sequences / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D016415:Sequence Alignment; D020080:Tandem Repeat Sequences / Q000235:genetics
D021903:DNA, Ribosomal Spacer