Identification Of Intron Loss And Phylogenetic Evolution Of MRP1Gene And EndoB Gene In The Drosophila And Other Arthropod Species

Nuclear introns are finer molecular markers actually. Introns evolve faster and are less conservative than exons. Intron sequences are better fit for studying the evolution of closely related species. On the other hand, intron insertion positions are relatively conservative in large-scale evolution, which provide clues in understanding the long-term evolution history. We found that intron positions are related to the species’relationship. The more identical intron positions with the relationship closer, maybe the selective constraint changed after speciation and the introns gained or lost. Introns in the conservative amino acid sequence regions can not be easily lost, suggests their unknown function, the species with relatively far relationship show clearly difference in introns position, Genetic relationship far species introns position difference, this may be due to the species differentiation by the selection pressure after change, this kind of change including choice direction and strength.Intron loss in Drosophila have received much recognition. In this study the intron loss of MRP1/CG6214gene and endoB/CG9834gene were found respectively in Drosophila. In the current study, the sequence of MRP1/CG6214and D-endoB from Drosophila melanogaster and Drosophila virilis were compared respectively. The results indicated that Drosophila virilis had an extra intron which located in the exon2, implying that event of intron loss or gain might happen on this locus during evolutionary process. The extra intron was named as Intron Y and Intron Z. In order to track the evolution of the Intron, the orthologous nucleotide sequences of40arthropod species were cloned or annotated. Based on phylogenetic analysis, it was found that the Intron should be present in the common ancestor of arthropod species, more than420million years ago. In addition, the phylogenetic tree indicated that Intron Y and Intron Z were not foumd in all of the sophophora species and the other species.The phylogenetic tree based on the sequence date of MRP1gene and endoB gene strongly support previously proposed classification based on morphological and molecular data. So the phylogenetic tree is right, the intron loss and the systematic relationship is consistent, sophophora species without introns Y and Z get together for a separate, other have introns Y and Z get together another branches. Through the analysis of system development it is found that introns Y and Z were lost in the evolutionary process.