Molecular Phylogenetics And Biogeography Of Chauliodinae From Eastern Asia(Megaloptera:Corydalidae)

Fishflies(Corydalidae:Chauliodinae)with a total of ca.130 extant species are one of three major groups of the holometabolous insect order Megaloptera,showing a remarkably discontinuous geographical distribution.According to the fossil evidence,Chauliodinae might have originated not later than the Middle Jurassic(-160 MA).Currently,the hypothesis on the evolutionary history of fishflies was based primarily on the morphological data,but lacks test based on the molecular data.This dissertation presented molecular phylogeny and biogeography of Chauliodinae from eastern Asia.Main results in this study are outlined below.1.We determined the complete mitochondrial(mt)genomes of 25 specimens of fishflies,representing five genera and 23 species,and analyzed the basic structure of these mt genomes.We detected that the structure and gene sequencing of mt genomes are basically same,without mutation or rearrangement.Based on the sequences of mt genomes,we reconstructed the phylogenetic relationship of Chauliodinae.The result indicated that the Dysmicohermes clade was the sister group of the Archiehauliodes clade +the Protochauliodes clade.The divergence time estimation suggested that the divergence among the three major subgroups of fishflies occurred during the Late Jurassic and Early Cretaceous when the Pangaea was undergoing sequential breakup.2.Based on the sequences of mt genomes and multi-locus markers,we reconstructed the interspecific relationships of the genus Neochauliodes.The monophyly of the N.sinensis group is corroborated.Using species delimitation,we found four possible cryptic species.Combining the information of geographic distribution,we inferred that the speciation of Neochauliodes was in connection with some geographical isolation formerly taken place in eastern Asia.The general trend of the dispersal is from south to north in eastern Asia.3.Based on the sequences of mt genomes and multi-locus markers,we reconstructed the interspecific relationships of the genera Parachauliodes and Sinochauliodes,the result indicated that Sinochauliodes was nested in Parachauliodes,and it was assigned to be the sister group of the clade including P.asahinai and P.continentalis.Based on the ancestral area reconstruction,we postulated that Parachauliodes might have originated from the mainland Asia and subsequently invaded the islands of eastern Asia,and the speciation is related to the geographical isolation resulted from the formation of Taiwan,Ryukyu islands,Japan islands and other islands.