Molecular Phylogenetics Of Oestridae With Adaptive Evolutionary Insights Emphasized On The Representative Groups

Bot flies(Diptera: Oestridae)are obligate endoparasites adapted to a larval life in mammalian hosts.They are highly host specific,possessing remarkable morphological and biological diversities,and hence becoming the crucial family for revealing the evolutionary scenarios and adaptions of Calyptrate.Nevertheless,phylogenetic and evolutionary analysis of Oestridae has long been impeded by a lack of morphological and molecular data.In the present project,the specimens of Oestridae deposited in around 10 national museums worldwide were carefully examined.A series of new ultrastructures were detected and detailly documented through comprehensive comparative morphological studies using scanning electron microscopy(SEM),confocal laser scanning microscopy(CLSM)and micro computerized tomography(Micro-CT).Phylogenetic and evolutionary analysis of Oestridae was conducted utilizing both morphological characters and mitochondrial genomes.The main results are listed as follow:1.The first phylogenomic analysis covering all four bot fly subfamilies was conducted,supporting the monophyly of Oestridae and the sister-group relationship of Hypodermatinae and Oestrinae.The mitochondrial genomic analysis of Oestridae showed that the evolutionary rates varied considerably between subfamilies,with Hypodermatinae and Oestrinae exhibiting a faster average rate than Cuterebrinae and Gasterophilinae.Nucleotide composition was highly heterogenous,with Gasterophilinae possessing highest GC content and smallest genomic size,which might be explained by the hypothesis of energy efficiency trade-offs.2.The molecular identification system of 25 common oestrid species distributed in China was established,which supported that the traditional 650 bp barcode region near the 5? terminus of the cytochrome c oxidase subunit I serving as a better molecular marker for species-level identification.Species Gasterophilus flavipes(Olivier)was resurrected as a valid species utilizing both morphological and molecular data,after spending half a century as a synonym of G.haemorrhoidalis(Linnaeus).Besides,the data suggested that the species of Pallasiomyia and Przhevalskiana need further taxonomic revision.3.The general and ultra-morphology of all the Gasterophilinae species in the world were examined through multiple microscopy techniques.The phylogeny of Gasterophilinae was analyzed at the specieslevel for the first time,using around 200 characters from all developmental stages(egg,larva,adult).Monophyly of Gasterophilinae is strongly supported.For the larvae,the strong and developed mouthhooks and the dense sensilla on the surface seem to contribute in locating species-specific parasitic sites.For the adults,the numerous sensory pits clustered on antennal post-pedicel might be an applicable strategy for enhancement of olfactory accuracy to increase the number of sensilla,trap odor molecules,facilitate odor detection,and enhance olfactory sensitivity.4.The first phylogenetic study of Portschinskia was presented through examining all the known 11 species,establishing four new species and a new junior synonym.The data showed that the modal color pattern of Portschinskia species is the same as for bumblebees,and a regional correlation in species diversity and color patterns can be detected between sympatric Portschinskia and Bombus species.As a result,we suggest that color patterns of Portschinskia can be explained as Batesian mimicry tracking locally dominant bumblebees.