Phylogenetic Positions Of Nine Lordiphosa-like Species Based On Multiple-locus DNA Sequences

Fliesof the genus Drosophila play important roles in the genetics.They were known to be distributed all over the world,with high species diversity,including a series of model species,such as Drosophila melanogaster.In recent years,molecular biological studies shewed that the subgenus Sophophora of the genus Drosophila,containing important model organisms,such as Drosophila melanogaster and Drosophila pseudoobscura,is not monophyletic with respect to the genus Lordophosa.Species of Lordiphosa are morphologically similar to those of Sophophora.Recently,Gao et al.discovered a number of species which show close morphological affinity to Lordophosa,thus were named as “Lordophosa-like spp.”.In order to investigate the phylogenetic relationship between Lordiphosa-like spp.and Lordiphosa,nine putative “Lordophosa-like spp.”were identified in light of morphological features and DNA barcodes.Subsequently,we reconstruced the phylogenetic relationships of thity-five species of the Lordiphosa-like spp.,Lordiphosa,Sophophora,Hirtodrosophila and the subgenus Drosophila,based on combined DNA sequence of seven nuclear genes,using the maxium likelihood,bayesian and neighbor-joining methods,respectively.The topological structure results of the three methods are completely identical,showing that:(1)The Lordiphosa-like spp.are most closely related to the genus Lordiphosa,consistent with the fact that they are highly similar in morphology.Eight Lordiphosa-like spp.formed a monophletic group,meanwhile the orther one combined with the genus Lordiphosa became the sister group,whoes genetic distance with Lordiphosa-like spp.is significantly larger than with the genus Lordiphosa.(2)The five species of the genus Lordiphosa formed a monophyletic group,supporting the monophyly status of this genus.(3)The branch combined the genus Lordiphosa and Lordiphosa-like spp.is most closely related to saltan-willistoni clade,which is the new world clade of the subgenus Sophophora.(4)H.duncani,which was classified to the genus Hirtodrosophila,is likely to be closely related to melanogaster-obscura clade,i.e.,the old world Sophophora.They collectively formed a sister group of the new world Sophophora,the genus Lordiphosa and Lordiphosa-like spp..The results suggest that the Lordiphosa-like spp.except for sp.X01 are close to Lordiphosa,some species of which may form an independent group.Understanding of the phylogenetic relationship of the Lordiphosa-like spp.lent support to the species identification of these newspecies,and provide new insight in to taxonom and phylogenetic researches of both Lordiphosa and Sophophora.