Phylogenetic Study Based On Mitochondrial Cytochrome B Gene Sequences Of10Species Of Birds In The Family Rallidae

Rallidae species in the world are widely distributed in vast areas outside the polar regions, deserts and high mountains above the snow line region. It is one of the most widely distributed species of terrestrial vertebrates, and also in Gruiformes. Rallidae is the largest class in the Gruiformes, but there has some controversy about its taxonomic status. It is difficult to construct their phylogenetic relationships based on the fossil records because the fossils are rarely been found.So, in this study, based on the mitochondrial cytochrome b gene we analysed the phylogenetic relationships about10species of Rallidae. After alignment, contrast and cutting, we got a total sequence of934bp. There were346variable sites, obtained319parsimony informative and27singleton variable sites, and no insertions or deletions found in all sequences. The number of substitution in the third codon sites was higher than other two codon sites. The transition to transversion ratio was1.54, reached saturation. The average content of the four bases (Thymine, Cytosine, Adenine and Guanine) in all species were25.2%(T),32.7%(C),28.6%(A) and13.5%(G), Where Cytosine (C) showed the highest content and Guanine (G) had the lowest content. And the four kinds of bases in average showed a high bias.The crane (Grus leucogeranus) and the Great Bustard (Otis tarda) were regarded as outgroups. The phylogenetic trees of10species of Rallidae were constructed by maximum parsimony (MP), neighbor joining (NJ), maximum likelihood (ML) and Bayesian methods respectively. The analysis results indicated all species were divided into5genera. The genus relationships were formed between White-breasted Waterhen(Amaurornis phoenicurus) and Watercock(Gallicrex cinerea), between Common Coot(Fulica atra) and Common Moorhen(Gallinula chloropus), between Slaty-breasted Rail(Gallirallus striatus) and Water Rail(Rallus aquaticus), between Brown Crake(Amaurornis akool) and Baillon’s Crake(Porzana pusilla) and between Ruddy-breasted Crake(Porzana fusca) and Band-bellied Crake(Porzana paykullii). There were4main branches in all4trees. The first branch was formed by the genus of Brown Crake and Baillon’s Crake and the gunus of Ruddy-breasted Crake and Band-bellied Crake; The second branch was formed by the genus of White-breasted Waterhen and Watercock; The third branch was formed by the genus of Common Coot and Common Moorhen; The forth branch was formedby the genus of Slaty-breasted Rail and Water Rail. The results of this study have basically reflected the relationship among the10kinds of the Rallidae birds’ classification.Based on the Cyt b gene nucleotide substitutions rate of Rallidae birds (0.82%per million years), we calculated the divergence time as follows:Brown Crake seperated from Baillon’s Crake separation at11.69MY; Ruddy-breasted Crake and seperated from Band-bellied Crake at10.38MY; White-breasted Waterhen seperated from Watercock at11.36MY; Common Coot seperated from Common Moorhen at16.78MY; Slaty-breasted Rail seperated from Water Rail at12.14MY. The divergence time between genera were as follows:the genus of Brown Crake and Baillon’s Crake and the gunes of Ruddy-breasted Crake and Band-bellied Crake has the closest genetic relationship, the divergence time between them was the latest, about14.10MY; The genus of Brown Crake and Baillon’s Crake and the genus of White-breasted Waterhen and Watercock has the earliest divergence time,20.89MY. Which except the genus of Brown Crake and Baillon’s Crake and the gunes of Ruddy-breasted Crake and Band-bellied Crake had the closest genetic relationship, the genetic relationship between the other genera were relatively longer.Rallidae birds are all important wetland indicators in China. There are great significances to give more in-depth researches and conservations for them both in wetland biodiversity and ecosystem diversity.