Search

Oil-tea (Camellia oleifera) is a woody oil crop whose nectar includes galactose derivatives that are toxic to honey bees. Interestingly, some mining bees of the genus Andrena can entirely live on the nectar (and pollen) of oil-tea and are able to metabolize these galactose derivatives. We present the first next-generation genomes for five and one Andrena species that are, respectively, specialized and non-specialized oil-tea pollinators and, combining these with the published genomes of six other Andrena species which did not visit oil-tea, we performed molecular evolution analyses on the genes involved in the metabolizing of galactose derivatives. The six genes (NAGA, NAGA-like, galM, galK, galT, and galE) involved in galactose derivatives metabolism were identified in the five oil-tea specialized species, but only five (with the exception of NAGA-like) were discovered in the other Andrena species. Molecular evolution analyses revealed that NAGA-like, galK, and galT in oil-tea specialized species appeared under positive selection. RNASeq analyses showed that NAGA-like, galK, and galT were significantly up-regulated in the specialized pollinator Andrena camellia compared to the non-specialized pollinator Andrena chekiangensis. Our study demonstrated that the genes NAGA-like, galK, and galT have played an important role in the evolutionary adaptation of the oil-tea specialized Andrena species. [ABSTRACT FROM AUTHOR]

Leeches secrete various biologically active substances which have important medical and pharmaceutical values in antithrombotic treatments. Here, we provide a high quality genome of two Asian medicinal leeches Hirudo nipponia and Hirudo tianjinensis , based on which, we identified 22 antithrombotic gene families, including fourteen coagulation inhibitors, four platelet aggregation inhibitors, three fibrinolysis enhancers, and one tissue penetration enhancer. The total numbers of antithrombotic genes were similar between H. nipponia (N = 86) and H. tianjinensis (N = 83). Molecular evolution analysis showed that no significant differences were detected between the two species in any of the three selection indices (dN , dS , and dN/dS), nor in the number of sites under positive/purifying selection. RNA-Seq based gene expression analysis showed that the overall expression patterns of the antithrombotic gene families were not significantly deviated between the two species. Our results indicated that there were rather close similarities between the two leeches on genomic characteristics, especially for the molecular evolution and expression of antithrombotic genes. Our study provides the most comprehensive collection of antithrombotic biomacromolecules from the two Asian medicinal leeches to date. These results will greatly facilitate the research and application of leech derivatives for medical and pharmaceutical purposes of thrombosis. [ABSTRACT FROM AUTHOR]

Leeches secrete various biologically active substances which have important medical and pharmaceutical values in antithrombotic treatments. Here, we provide a high quality genome of two Asian medicinal leeches Hirudo nipponia and Hirudo tianjinensis , based on which, we identified 22 antithrombotic gene families, including fourteen coagulation inhibitors, four platelet aggregation inhibitors, three fibrinolysis enhancers, and one tissue penetration enhancer. The total numbers of antithrombotic genes were similar between H. nipponia (N = 86) and H. tianjinensis (N = 83). Molecular evolution analysis showed that no significant differences were detected between the two species in any of the three selection indices (dN , dS , and dN/dS), nor in the number of sites under positive/purifying selection. RNA-Seq based gene expression analysis showed that the overall expression patterns of the antithrombotic gene families were not significantly deviated between the two species. Our results indicated that there were rather close similarities between the two leeches on genomic characteristics, especially for the molecular evolution and expression of antithrombotic genes. Our study provides the most comprehensive collection of antithrombotic biomacromolecules from the two Asian medicinal leeches to date. These results will greatly facilitate the research and application of leech derivatives for medical and pharmaceutical purposes of thrombosis. [ABSTRACT FROM AUTHOR]

DNA barcoding has become a promising tool for species identification and phylogeny in a wide range of animal taxa using mitochondrial cytochrome c oxidase subunit I (COI). The Corvidae (Aves: Passeriformes) is a species rich and morphologically diverse family. In the present study, we analyzed the COI barcodes of 39 species from 12 genera of Corvidae. COI gene was also used to examine phylogenetic relationships of Corvidae. Every species possessed a barcode distinct from that of other species. Kimura two-parameter distances were calculated between species barcodes. The average genetic distance between the species was 22 times higher compared to the average genetic distance within species. Maximum likelihood method was used to construct a phylogenetic tree. All the species could be discriminated by their distinct clades in the phylogenetic tree. COI gene data provided good evidence for the monophyly of the Corvidae. Members of Cyanopica and Pyrrhocorax were the first to split from the Corvidae lineage. Analysis of COI genes supported the others genera fell into two clades. DNA barcoding is an effective molecular tool for Corvidae species identification and phylogenetic inference. [ABSTRACT FROM AUTHOR]

The superfamily Sylvioidea contains the most diversified species within the Passerida. The grey-cheeked fulvetta (Alcippe morrisonia) and the eyebrowed wren-babbler (Napothera epilepidota) are birds with a weak flight that live in lightly wooded or scrubland environments. In the present study, two new mitogenomes of A. morrisonia (KX376475) and N. epilepidota (KX831093) within the superfamily Sylvioidea were sequenced and their total lengths were 17 788 bp and 17 913 bp, respectively. Both mitogenomes comprised 13 protein-coding genes, 22 tRNAs, 2 rRNAs and two control regions (CR and CCR). Similar to most metazoans, both mitogenomes and their protein-coding genes encoded on the H-strand displayed typical positive AT skews and negative GC skews. Bayesian inference and maximum-likelihood phylogenetic analyses were conducted on the basis of partitioned data of mitogenomes and two identical topologies were observed. The family-level phylogenetic relationships ((((Pellorneidae, Leiothrichidae) Timaliidae) Zosteropidae) Sylviidae) among the superfamily Sylvioidea were strongly supported. Within the family Pellorneidae, A. morrisonia clustered with N. epilepidota. Within Leiothrichidae, we further demonstrated that Babax lanceolatus is sister to Garrulax perspicillatus , and Spizixos semitorques was nested within the genus Pycnonotus according to the mitogenomic data and we propose that the generic placement of Spizixos should be reconsidered. Family-level phylogenetic relationships of the superfamily Sylvioidea have always been debated and the mitogenome data have a high probability of resolving intractable phylogenetic relationships. On the basis of mitogenome data, the family-level phylogenetic relationships ((((Pellorneidae, Leiothrichidae) Timaliidae) Zosteropidae) Sylviidae) among the superfamily Sylvioidea were strongly supported and Spizixos semitorques was nested within the genus Pycnonotus. We propose that the generic placement of Spizixos should be reconsidered. [ABSTRACT FROM AUTHOR]

Despite being a non-hematophagous leech, Whitmania pigra is widely used in traditional Chinese medicine for the treatment of antithrombotic diseases. In this study, we provide a high quality genome of W. pigra and based on which, we performed a systematic identification of the potential antithrombotic genes and their corresponding proteins. We identified twenty antithrombotic gene families including thirteen coagulation inhibitors, three platelet aggregation inhibitors, three fibrinolysis enhancers, and one tissue penetration enhancer. Unexpectedly, a total of 79 antithrombotic genes were identified, more than a typical blood-feeding Hirudinaria manillensis, which had only 72 antithrombotic genes. In addition, combining with the RNA-seq data of W. pigra and H. manillensis, we calculated the expression levels of antithrombotic genes of the two species. Five and four gene families had significantly higher and lower expression levels in W. pigra than in H. manillensis, respectively. These results showed that the number and expression level of antithrombotic genes of a non-hematophagous leech are not always less than those of a hematophagous leech. Our study provides the most comprehensive collection of antithrombotic biomacromolecules from a non-hematophagous leech to date and will significantly enhance the investigation and utilization of leech derivatives in thrombosis therapy research and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

The control region is the major noncoding segment of animal mitochondrial DNA. To infer the structure and variation of Fringillidae mitochondrial DNA control region, the entire control region sequences of 25 species were analyzed. The length of the control region sequences was very conserved (1230 ± 18) and can be separated into three domains. The frequency of both substitutions and gaps was highest in the third domain and lowest in the central region. The control region has the same flanking gene order from tRNAGluto tRNAPhe. Genetic distances between species ranged from 1.80% (betweenCarduelis pinusandCarduelis spinus) to 25.34% (betweenCarduelis sinicaandCoccothraustes vespertinus). The average genetic distances among the species within the genera varied from 5.11% (Leucosticte) to 14.31% (Carpodacus). The average genetic distances showed insignificantly negative correlation with ts/tv. Domain III is the most variable of the three domains among all the genera. The control region of Fringillidae contains a putative TAS element and the highly conserved CSB-1, and F, E, D, C boxes. However, neither CSB-2 nor CSB-3 could be unambiguously identified in the Fringillidae. The maximum likelihood method was used to construct a phylogenetic tree. Control region analysis demonstrated that some currently recognized genera may be polyphyletic, includingCarpodacus, CarduelisandSerinus. [ABSTRACT FROM PUBLISHER]

The avian genera Calidris and Tringa are the largest of the widespread family of Scolopacidae. The phylogeny of members of the two genera is still a matter of controversial. Mitochondrial cytochrome c oxidase subunit I (COI) can serve as a fast and accurate marker for the identification and phylogeny of animal species. In this study, we analyzed the COI barcodes of thirty-one species of the two genera. All the species had distinct COI sequences. Two hundred and twenty-one variable sites were identified. Kimura two-parameter distances were calculated between barcodes. Neighbor-joining and maximum likelihood methods were used to construct phylogenetic trees. All the species could be discriminated by their distinct clades in the phylogenetic trees. The phylogenetic trees grouped all the species of Calidris and Tringa into different monophyletic clade, respectively. COI data showed a well-supported phylogeny for Calidris and Tringa species. [ABSTRACT FROM AUTHOR]

The family Ranidae has the widest distribution compared with other frog family. The phylogeny of the Ranidae is still a matter of dispute. In the present study, we analyzed the COI barcodes of 29 species from six genera belonging to the family Ranidae. Twenty-seven species (93.10% of all the species) were correctly identified by their DNA barcodes.Pelophylax lessonaeandPelophylax ridibundusshared the same one barcode sequence. Kimura two-parameter distances were calculated between barcodes. Pair-wise comparisons among-species were distributed from 0.16% (betweenPelophylax lessonaeandPelophylax esculenta) to 29.13% (betweenRana warszewitschiiandRana dybowskii). The average genetic distance between species was 28 times higher than the average genetic distance within species. The neighbor-joining method was used to construct a phylogenetic tree, which grouped all the genera into two divergent clades. The results indicated that some currently recognized genera of Ranidae may not be monophyletic.COIgene data supported the hypothesis of polyphyly forRana, Amolops, Babina,andHylarana. DNA barcoding is an effective molecular tool for Ranidae species identification and phylogenetic inference. [ABSTRACT FROM AUTHOR]

The control region is the major non-coding segment of animal mitochondrial DNA. To infer the structure and variation of Anseriformes mitochondrial DNA control region, the control region sequences of 52 species were analyzed. The length of the control region sequences ranged from 968 bp (Chenonetta jubata) to 1335 bp (Anseranas semipalmata) and can be separated into three domains. There is a deletion of 100–130 bp in Anatinae, compared to other groups of Anserinae. The average genetic distances among the species within the genera varied from 4.14% (Anser) to 10.58% (Cygnus). The average genetic distances showed insignificantly negative correlation with ts/tv. Domain I is the most variable among the three domains among all the genera. Five conserved sequence boxes in the domain II of Anseriformes sequences were identified. The alignment of the Anseriformes five boxes sequences showed considerable sequence variation. CSB-1, -2 and 3 were not found in the Anseriformes. Maximum-likelihood method was used to construct a phylogenetic tree, which grouped all of the genera into four divergent clades.Anseranas + ChaunaandDendrocygnawere identified as early offshoots of the Anatidae. All the remaining taxa fell into two clades that correspond to the two subfamilies Anserinae and Anatiane. [ABSTRACT FROM PUBLISHER]

The mitochondrial DNA control region is an area of the mitochondrial genome which is non-coding DNA. To infer the structural and evolutionary characteristics of Phasianidae mitochondrial DNA control region, the entire control region sequences of 34 species were analyzed. The length of the control region sequences ranged from 1144 bp (Phasianus colchicus) to 1555 bp (Coturnix japonica) and can be separated into three domains. The average genetic distances among the species within the genera varied from 1.96% (Chrysolophus) to 12.05% (Coturnix). The average genetic distances showed significantly negative correlation with ts/tv. In most genera (exceptCoturnix), domain I is the most variable among the three domains. However, the first 150 nucleotides apparently evolved at unusually low rates. Four conserved sequence boxes in the domain II of Phasianidae sequences were identified. The alignment of the Phasianidae four boxes and CSB-1 sequences showed considerable sequence variation. [ABSTRACT FROM AUTHOR]

Leeches are well-known annelids due to their obligate blood-feeding habits. Some leech species secrete various biologically active substances which have important medical and pharmaceutical value in antithrombotic treatments. In this study, we provided a high-quality genome of the Asian buffalo leech (Hirudinaria manillensis), based on which we performed a systematic identification of potential antithrombotic genes and their corresponding proteins. Combining automatic and manual prediction, we identified 21 antithrombotic gene families including fourteen coagulation inhibitors, three platelet aggregation inhibitors, three fibrinolysis enhancers, and one tissue penetration enhancer. A total of 72 antithrombotic genes, including two pseudogenes, were identified, including most of their corresponding proteins forming three or more disulfide bonds. Three protein families (LDTI, antistasin, and granulin) had internal tandem repeats containing 6, 10, and 12 conserved cysteines, respectively. We also measured the anticoagulant activities of the five identified hirudins (hirudin_Hman1 ~ hirudin_Hman5). The results showed that three (hirudin_Hman1, hirudin_Hman2, and hirudin_Hman5), but not the remaining two, exhibited anticoagulant activities. Our study provides the most comprehensive collection of antithrombotic biomacromolecules from a leech to date. These results will greatly facilitate the research and application of leech derivatives for medical and pharmaceutical purposes in the treatment of thrombotic diseases. [ABSTRACT FROM AUTHOR]

The golden pheasant (Chrysolophus pictus) is an endemic pheasant of central China and is protected under national legislation. The Qinling Mountains form a natural barrier between northern and southern China. We investigated the population genetic structure using 1123 nucleotides of mitochondrial DNA (mtDNA) control-region from 55 individuals sampled from five populations of gold pheasant in the Qinling Mountains. We found sixteen haplotypes defined by fourteen polymorphic sites. Phylogenetic analyses showed that the haplotypes sampled from the five putative populations did not cluster into separate geographic branches. There was an insignificant genetic differentiation among the putative populations (except GSTS population), probably due to high levels of gene flow. Results from the mismatch distribution and neutrality test analyses indicated the populations did not experience a range expansion over the course of their histories. They also suggested there was no geographical isolation shaped by the Qingling Mountains for Chrysolophus pictus. [ABSTRACT FROM AUTHOR]

Abstract: Chinese bamboo partridge (Bambusicola thoracica thoracica), an endemic subspecies of south China, distributes in mountainous areas that were affected by climate changes throughout the Pleistocene. We investigated the potential impact of cyclical Pleistocene climate changes on phylogeographic patterns using 1140 nucleotides of mitochondrial DNA (mtDNA) control-region from 180 individuals sampled from 13 populations of the partridge. We found 50 haplotypes defined by 39 polymorphic positions. Phylogenetic analyses revealed two robustly supported clades. There was a significant genetic differentiation among the populations with little gene flow. Refugia were identified in the southwestern mountains and Luoxiao Mountains in China, implying that topographic complexity played a substantial role in providing suitable habitats for the partridge during cold periods. Results from the mismatch distribution and neutrality test analysis suggested a range expansion of the two clades. The mtDNA marker suggested the existence of a geographical structure among Chinese bamboo partridge populations, resulting from the synergistic affect of Pleistocene climatic variations. [Copyright &y& Elsevier]

Mitochondrial cytochrome c oxidase subunit I (COI) has been used as a powerful marker in a variety of phylogenetic studies. According to studies of bird species, the 694-bp sequence of the mitochondrial gene encoding COI is extremely useful for species identification and phylogeny. In the present study, we analyzed the COI barcodes of 79 species from 26 genera belonging to the Anatidae family. Sixty-six species (83.54%) of the species were identified correctly from their DNA barcodes. The remaining 13 species shared barcodes sequences with closely related species. Kimura two-parameter (K2P) distances were calculated between barcodes. The average genetic distance between species was 41 times higher compared to the average genetic distance within species. Neighbor-joining method was used to construct a phylogenetic tree, which grouped all of the genera into three divergent clades.DendrocygnaandNomonyx + Oxyurawere identified as early offshoots of the Anatidae. All the remaining taxa fell into two clades that correspond to the two subfamilies Anserinae and Anatiane. Based on our results, DNA barcoding is an effective molecular tool for Anatidae species identification and phylogenetic inference. [ABSTRACT FROM AUTHOR]

Abstract: The taxonomic status of some genera within the Phasianidae remains controversial. To demonstrate the phylogenetic relationships of four endemic genera (Tetraophasis, Ithaginis, Crossoptilon and Chrysolophus) and other 11 genera of Phasianidae in China, a total of 1070 nucleotides of mitochondrial DNA (mtDNA) control-region genes were sequenced. There are 376 variable sites including 345 parsimony sites. The genetic distance ranged from 0.067 (Chrysolophus and Phasianus) to 0.181 (Perdix and Bambusicola) among the 15 genera. Maximum likelihood method was used to construct a phylogenetic tree, which grouped all the genera into two deeply divergent clades. Perdix was shown to be a non-partridge genus. Alternatively, it appears ancestral to either partridges or pheasants. The sibling taxa of the four endemic genera were Lophophorus, Tragopan, Lophura and Phasianus, respectively. Calibrated rates of molecular evolution suggested that the divergence time between the four genera and related taxa was 4.00–5.00million years ago, corresponding to the Pliocene. Considering their molecular phylogenetics, fossil and geographical distribution patterns, the four endemic genera might have originated in the southwestern mountains in China. [Copyright &y& Elsevier]

Abstract: Rusty-necklaced partridges (Alectoris magna) are found in Qinghai, Ningxia and Gansu provinces of northwestern China, distributed in mountainous areas that were heavily affected by cyclical climate changes throughout the Pleistocene. We investigated the potential impact of Pleistocene range shifts on phylogeographic patterns using 458 nucleotides of mitochondrial control-region from 102 individuals sampled from 10 populations across the current range. We found 31 haplotypes defined by 33 polymorphic positions. Phylogenetic analyses revealed two robustly supported clades, one corresponding to the Chaidamu Basin and the other including all individuals from all other populations. At the population level we also found significant evidence of differentiation. The phylogeographic structure of the rusty-necklaced partridge is consistent with the “phylogenetic discontinuity, spatial separation” pattern outlined by Avise et al. [Avise, J.C., Arnold, J., Ball, R.M., Bermingham, E., Lamb, T., Niegel, J.E., Reeb, C.A., Saunders, N.C., 1987. Intraspecific phylogeography: the mitochondrial DNA bridge between population genetics and systematics. Ann. Rev. Ecol. Syst. 18, 489–522]. [Copyright &y& Elsevier]

The Spotted DoveSpilopelia chinensis(Columbiformes: Columbidae) is widely distributed in Southeast Asia. In the present study, we investigated the complete mitochondrial genome ofS. chinensisand the mitogenome is 16,964 bp in length, consists of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a non-coding control region, with the base composition of A 31.1%, G 13.9%, T 23.9%, and C 32.1%. A single extra base “C” at position 174 is inserted in geneNd3, similar to some other birds and turtles. The phylogenetic relationships using partitioned Bayesian inference based on the 12 concatenated PCGs indicated that ((((Spilopelia, Columba)Ectopistes) (Geotrygon(Leptotila, Zenaida)))Hemiphaga). While, more complete mitogenome sequences should be determined to confirm the phylogenetic status ofSpilopeliawithin family Columbidae. [ABSTRACT FROM AUTHOR]

The taxonomic status of the avian genus Pucrasia is controversial and unstable. To demonstrate the phylogenetic relationships of Pucrasia, the complete mitochondrial genome of 19 genera in Phasianidae were analyzed. The genetic distance between Pucrasia and other genus ranged from 0.124 (Tetraophasis) to 0.170 (Arborophila). Maximum likelihood method, neighbor-joining method and minimum-evolution method were used to construct molecular phylogenetic trees. The phylogenetic trees grouped all the genera into a monophyletic cluster. Pucrasia, Tragopan, Tetraophasis and Lophophorus were closely related genera, which were consistent with the shape and behavior. Calibrated rates of molecular evolution suggested that their divergent time was late Pliocene between Pucrasia and other genus. Pucrasia was shown to be pheasant genus based on morphological traits and complete mitochondrial genome. The origin of Pucrasia might have been influenced by the uplift of Himalayan and Pleistocene climate fluctuations. [ABSTRACT FROM AUTHOR]

Diet specialization may affect the population genetic structure of pollinators by reducing gene flow and driving genetic differentiation, especially in pollen‐specialist bees. Colletes gigas is a pollen‐specialist pollinator of Camellia oleifera, one of the most important staple oil crops in China. Ca. oleifera blooms in cold climates and contains special compounds that make it an unusable pollen source to other pollinators. Thus, C. gigas undoubtedly plays a key role as the main pollinator of Ca. oleifera, with biological and economic significance. Here, we use a population genomic approach to analyze the roles of geography and climate on the genetic structure, genetic diversity, and demographic history of C. gigas. A total of 1,035,407 SNPs were identified from a 582.77 Gb dataset. Clustering and phylogenetic analyses revealed a marked genetic structure, with individuals grouped into nine local clusters. A significant isolation by distance was detected by both the Mantel test (R =.866, p =.008) and linear regression (R2 =.616, p <.001). Precipitation and sunshine duration were positively and significantly (R ≥.765, p ≤.016) correlated with observed heterozygosity (Ho) and expected heterozygosity (He). These results showed that C. gigas populations had a distinct phylogeographic pattern determined by geographical distance and environmental factors (precipitation and sunshine duration). In addition, an analysis of paleogeographic dynamics indicated that C. gigas populations exhibited patterns of glacial expansion and interglacial contraction, likely resulting from post‐glacial habitat contraction and fragmentation. Our results indicated that the peculiar phylogeographic patterns in C. gigas populations may be related to their specialization under long‐term adaptation to host plants. This work improves our understanding of the population genetics in pollen‐specialist bees. The distinct genetic clusters identified in this study should be taken into consideration for the protection and utilization of this specialized crop pollinator. [ABSTRACT FROM AUTHOR]

Vitellogenin (Vg), a storage protein, has been significantly studied for its egg yolk precursor role in oviparous animals. Recent studies found that vitellogenin and its Vg‐like homologs were fundamentally involved in many other biological processes in social insects such as female caste differences and oxidative stress resilience. In this study, we conducted the first large‐scale molecular evolutionary analyses of vitellogenin coding genes (Vg) and Vg‐like genes of bumble bees, a primitively eusocial insect belonging to the genus Bombus. We obtained sequences for each of the four genes (Vg, Vg‐like‐A, Vg‐like‐B, and Vg‐like‐C) from 27 bumble bee genomes (nine were newly sequenced in this study), and sequences from the two closest clades of Bombus, including five Apis species and five Tetragonula species. Our molecular evolutionary analyses show that in bumble bee, the conventional Vg experienced strong positive selection, while the Vg‐like genes showed overall relaxation of purifying selection. In Apis and Tetragonula; however, all four genes were found under purifying selection. Furthermore, the conventional Vg showed signs of strong positive selection in most subgenera in Bombus, apart from the obligate parasitic subgenus Psithyrus which has no caste differentiation. Together, these results indicate that the conventional Vg, a key pleiotropic gene in social insects, is the most rapidly evolving copy, potentially due to its multiple known social functions for both worker and queen castes. This study shows that concerted evolution and purifying selection shaped the evolution of the Vg gene family following their ancient gene duplication and may be the leading forces behind the evolution of new potential protein function enabling functional social pleiotropy. [ABSTRACT FROM AUTHOR]

Background: The oriental rat flea (Xenopsylla cheopis), which infests several mammals, primarily rats (Rattus spp.), is the most notorious vector of human plague. In this study, we measured the genetic differentiation among populations of fleas from the Asian house rat (Rattus tanezumi) and the brown rat (R. norvegicus) using microsatellite markers in order to investigate the extent of host-switching in this parasite. Results: We developed 11 polymorphic microsatellite loci for our study, nine of which showed high potential for inbreeding. AMOVA showed that the majority (84.07%, P < 0.001) of the variation was derived from within populations, followed by variation among groups (14.96%, P < 0.001); in contrast, variation within groups of populations was nearly absent (0.97%, P > 0.05). Analyses of the pairwise fixation index revealed that most of the ten allopatric population pairs but none of the five sympatric population pairs were significantly differentiated. Moreover, based on genetic structure clustering analysis, there was obvious differentiation between allopatric populations but not between sympatric population pairs. Conclusions: These results indicate the presence of frequent migrations of the oriental rat flea between the sympatric Asian house rat and brown rat, causing a high rate of gene flow and limited genetic differentiation. We suggest that there is no clear boundary limiting the migration of oriental rat fleas between the two hosts, and thus both rat species should be monitored equally for the purposes of plague prevention and control. [ABSTRACT FROM AUTHOR]