Abstract: The mechanisms and evolutionary dynamics of intron insertion and loss in eukaryotic genes remain poorly known. A total of 604 protein-coding genes, which contain 12 585 introns and 3 074 conserved introns in distinct amino acid alignment sequences in orthologous genes from Vertebrata (Mus musculus, Rattus norvegicus and Homo sapiens), Diptera (Anopheles gambiae) and plant (Arabidopsis thaliana) were analyzed using systematic methods to assess the causes of present-day distribution of introns in different lineages. The results demonstrated that more than 850 introns lost in Diptera evolution and more than 1 600 introns gained in Vertebrata evolution, but the intron gain in Diptera evolution and intron loss in Vertebrata evolution are relatively less. Additionally, along with yeast, the distribution of introns in Diptera exhibits a bit more prevalent in the 5′end of genes, which was not found in vertebrates and plants. This may be due to intron loss mostly occurring in 3′end of genes in Diptera evolution. Meanwhile statistical results indicate that phase 0 intron is most common in the three species in Vertebrata, and this might be the consequence of that phase 0 intron was the most frequently gained intron type in evolution.

Key words: Diptera, Vertebrata, plant, intron loss, phylogeny