Molecular Taxonomic Redefinition Of Three Species Of Sciuridae In Hainan Island And Their Characteristics Of Mitochondrial Genome

The family Sciuridae (Mammalia:Rodentia), with about278species in51genera, widely distributed around the world. Phylogenetic relationship of some species in this family is not yet clear, for example, Hainan Hying squirrel (Pelaurista hainana) is whether a distinct species or not. Animal mitochondrial genome has unique advantages in study of phylogenetic relationship, and is widely used in researches of genome structure, function and evolutionary relationships. We sequenced complete mitohondrial genomes of three species of Sciuridae collecxted from Hainan Island, including Hainan flying squirrel (Pelaurista hainana), Indochinese flying squirrel (Hylopeles phayrei electilis) and Asian red-cheeked squirrel (Dremomys rufigenis) in this study, and downloaded the complete mitohondrial genomes of Eurasian red squirrel (Sciurus vulgaris), Siberian flying squirrel (Pleromys volans) and Himalayan marmot (Marmota himalayana) from GenBank, the characteristies of mitochondrial genome for these six Sciuridae species were analysed. Results show that they have similar structures, containing13proten-coding genes,22tRNA.2rRNA and2sections of non-coding region. Protein-coding genes ND6and8tRNA genes are encoded by the light strand and the heavy strand encod other genes. The A+T content of the genomes is greater than the G+C content, so the genomes have A+T bias. All the22tRNA genes have a typical clover leaf structure except tRNA-SerAGY, which is lack the DHU arm. Non-coding region is divided into two sections. The control region (D-loop region) are divided into three zones:extended termination-associated sequences, central domain and conserved sequence block.This study reconstructed three phylogenetic trees based on cyt b genes of our sequences and those deposited in GenBank and tried to explore the phylogeny of the family Sciuridae. The main conclusions are summarized as follows.1. Hainan flying squirrel (Pelaurista hainana) is a distinct species in Hainan Island, which is not the subspecies of Pelaurista philippensis or Petaurista albiventer.2. Indochinese flying squirrel (Hylopeles phayrei electilis) which is distributed in Hainan Island is a possible distinct species (Hylopeles electilis).3. Asian red-cheeked squirrel (Dremomys rujigenis) which is distributed in Hainan Island is neither the same species with Asian red-cheeked squirrel from Yunnan nor conspecific species with Red-hipped squirrel (Dremomys pyrrhomerus) from Yunnan. This maybe a distinct species should be named as Dremomys hainana.4. Flying squirrels are monophyletic, Steppan’s suggestion that subfamilial status of flying squirrels is not warranted. The genus Sciurus is a sister group of flying squirrels. They should belong to the subfamily Sciurinae, and flying squirrels maybe evolved from tree squirrels.5. The genus Marmota is not monophyletic, and the taxonomic status of M. olymus is worthy of further study. In the phylogenetic trees the prairie dogs genus Cynomys are grouped with the subgenera Xerospermophilus, Ictidomys and Poliocitellus. The genus Spermophilus is paraphyletic.