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1.
Trypanosoma (Megatrypanum) melophagium is a parasite of sheep transmitted by sheep keds, the sheep-restricted ectoparasite Melophagus ovinus (Diptera: Hippoboscidae). Sheep keds were 100% prevalent in sheep from five organic farms in Croatia, Southeastern Europe, whereas trypanosomes morphologically compatible with T. melophagium were 86% prevalent in the guts of the sheep keds. Multilocus phylogenetic analyses using sequences of small subunit rRNA, glycosomal glyceraldehyde-3-phosphate dehydrogenase, spliced leader, and internal transcribed spacer 1 of the rDNA distinguished T. melophagium from all allied trypanosomes from other ruminant species and placed the trypanosome in the subgenus Megatrypanum. Trypanosomes from sheep keds from Croatia and Scotland, the only available isolates for comparison, shared identical sequences. All biologic and phylogenetic inferences support the restriction of T. melophagium to sheep and, especially, to the sheep keds. The comparison of trypanosomes from sheep, cattle, and deer from the same country, which was never achieved before this work, strongly supported the host-restricted specificity of trypanosomes of the subgenus Megatrypanum. Our findings indicate that with the expansion of organic farms, both sheep keds and T. melophagium may re-emerge as parasitic infections of sheep.  相似文献   

2.
Genetic variation at 53 protein-coding loci (25 polymorphic) was analysed for 17 water buffalo populations – 12 swamp, three Lankan and two of the Murrah breed (river type), to determine the magnitude of genetic differentiation and the genetic relationships among the populations. In accord with previous cytological studies, the Lankan buffalo clearly are river type. Significant deviations from Hardy–Weinberg equilibrium were shown for a number of locus–population combinations, with all populations but one showing significant heterogeneity in these deviations among loci. By contrast, heterogeneity among populations for each locus was much less, indicating locus-specific deviations, which suggest selection affecting allele frequencies at some loci. There was significant genetic differentiation among populations of both the swamp and river types. The differentiation among the swamp populations may reflect the geography of south-east Asia and the presumed spread of the swamp buffalo through this region. Phylogenies derived from pairwise genetic distance estimates show the clear separation of swamp and river types, but the topology of the swamp populations shows rather poor consistency with their geographic locations. For at least one population (Australia), it is clear that bottleneck effects have distorted the phylogenetic topology. Average genetic distances for both the swamp and river types, as compared with previous studies of livestock breeds, show that the genetic differentiation of each of these sets of populations is of the same order of magnitude as that among well-recognized and established breeds of other species.  相似文献   

3.
Infection with hepatitis B virus (HBV) was detected by serological testing for HBV surface antigen and by PCR assay for HBV DNA in serum samples from two common chimpanzees (Pan troglodytes subsp. verus) born in West Africa. The complete genome sequences obtained by nucleotide sequencing of overlapping DNA fragments amplified by PCR were compared with HBV variants recovered from other primates and with human genotypes A to F. Both chimpanzee sequences were 3, 182 nucleotides in length, and the surface gene sequence predicted the existence of a, d, and w serological determinants. Neither sequence contained stop codons in the precore region. On phylogenetic analysis, the HBV variants infecting the chimpanzees clustered together with a third chimpanzee HBV isolate independently obtained from an infected captive animal (A. J. Zuckerman, A. Thornton, C. R. Howard, K. N. Tsiquaye, D. M. Jones, and M. R. Brambell, Lancet ii:652-654, 1978), with an overall sequence similarity of >94%. This provides strong evidence for a chimpanzee-specific genotype of HBV which circulates in nature. These findings add to the recent evidence for infection in the wild of other Old and New World primates (gibbon, orangutan, and woolly monkey) with species-specific variants of HBV. There is no evidence for close phylogenetic clustering of variants found so far in primates with any of the established HBV genotypes from humans. With the new evidence for the widespread distribution of HBV in primates, hypotheses for the origins of human infection are reviewed.  相似文献   

4.
The genus Pseudo-nitzschia includes several species capable of producing domoic acid, the causative agent of Amnesic Shellfish Poisoning. Some of these species have been recorded frequently in the Gulf of Naples. For one of the species, P. multistriata, which has been recurrently found in our sampling area since 1995, this is the first report for European waters. Here we provide further details on the fine structure of this species. Pseudo-nitzschia multistriata was the only one found to produce domoic acid among all the Pseudo-nitzschia species from the Gulf of Naples, and this finding raises the number of potentially toxic species in this genus to nine. Phylogenetic relationships among several Pseudo-nitzschia species were assessed using the hypervariable domains (D1–D3) of the large subunit (LSU) rDNA. The match between the phylogeny obtained and important taxonomic characters used in this genus are discussed. Results show that P. multistriata clusters with wider species lacking a central larger interspace in the raphe. Close genetic relationships were determined between P. fraudulenta and P. subfraudulenta, and between P. pungens and P. multiseries. Genetic differences among these pairs of species are comparable to those among isolates of P. pseudodelicatissima from the Gulf of Naples, indicating high intraspecific genetic diversity of Pseudo-nitzschia species in the relatively conserved LSU region. This could explain the problematic results obtained when testing a match between species-specific Pseudo-nitzschia LSU probes and our sequences.  相似文献   

5.
Seventy-five individuals of Bubalus bubalis belonging to four different breeds, three of river buffalo and one of swamp buffalo, were studied for polymorphism in MHC DRB (Bubu-DRB) and DRA (Bubu-DRA) loci. Eight alleles of Bubu-DRB were found, and all alleles in the swamp type were shared with the three river breeds. All alleles sampled from the breed of European origin (Mediterranean) were present in breeds sampled in Brazil, thus variability of this locus may have been preserved to a great extent in the more recently founded Brazilian population. Bubu-DRB alleles contained higher proportions of synonymous vs. non-synonymous substitutions in the non-peptide-binding sites (PBS) region, in contrast to the pattern of variation found in BoLA-DRB3, the orthologous locus in cattle. This indicated that either the first domain exon (exon 2) of Bubu-DRB has not undergone as much recombination and/or gene conversion as in cattle alleles, or Bubu-DRB may be more ancient than BoLA-DRB3 alleles. Phylogenetic analysis of DRB alleles from Bubalus, Syncerus c. caffer, the Cape buffalo, and domestic cattle demonstrated transspecies polymorphism. Water buffalo contained two alleles of DRA that differed from each other in two amino acid positions, including one in the PBS (alpha22) that was also shared with Anoa depressicornis, the anoa. Discovery of variation in DRA was surprising as the first domain of DRA is a highly conserved polypeptide in mammals in general and especially in ruminants, where no other substitution in PBS was seen.  相似文献   

6.
7.
The Balkan endemic species Microtus (Terricola) thomasi – Thomas' vole – is widely distributed in the Greek mainland and presents regionally confined karyotypic forms. In order to test the significance of geographical isolation and/or karyological differences in microevolutionary processes at the intraspecific level we used restriction enzymes and partial sequencing to study the polymorphism of the mtDNA d -loop control region in ten Greek populations. An overall high rate of both inter- and intrapopulation polymorphism was observed. The mtDNA diversity was unevenly distributed so that most of the populations studied were very similar and closely related, and only a few of them were clearly differentiated from the others. The mtDNA analysis failed to reveal any clear variation pattern that could be correlated with karyotypic forms or geographical proximity of the populations studied. Instead, the mtDNA phylogeny gave evidence in support of the coexistence of non-polymorphic (2 n  = 44) and polymorphic (2 n  < 44) karyotypic forms within the ancestral Greek M. (T.) thomasi stock. Interestingly, only one population (Agios Stefanos) seemed to significantly diverge from all the others in both methods used, forming a well-supported paraphyletic clade. Allozymic studies have already reported similar results, corroborating the genetic peculiarity of this population.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 55–68.  相似文献   

8.
Lithospermum (Boraginaceae) includes ca. 60 species and exhibits a wide range of floral, palynological, and vegetative diversity. Phylogenetic analyses based on 10 chloroplast DNA regions and 22 morphological characters were conducted in order to (i) examine evolutionary relationships within Lithospermum and among related genera of Boraginaceae, and (ii) investigate patterns of morphological evolution. Several morphological features, such as long‐funnelform corollas, faucal appendages, reciprocal herkogamy, and evident secondary leaf venation, have evolved multiple times within the genus. In contrast, other morphological features, including the presence of glands and the position and number of pollen pores, are less plastic and tend to characterize larger clades. Some features, including the presence of glands, are interpreted as symplesiomorphic for Lithospermum, while others, such as evident secondary leaf venation, appear to have originated repeatedly. The range of structural diversity that occurs among the species of Lithospermum suggests the potential utility of this genus as a model for integrative studies of evolution, development, and molecular biology.© The Willi Hennig Society 2011.  相似文献   

9.
A phylogenetic analysis was conducted on sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA in 23 species ofAveneae (Poaceae subfam.Pooideaae). These sequences ofHelictotrichon spp.,Arrhenatherum elatius, Avena spp.,Trisetum spp.,Koeleria spp.,Holcus lanatus, Alopecurus vaginatus together with published ITS sequences of furtherAveneae, Poeae, Triticeae, andBromeae were analysed by the neighbor-joining distance method to assess the molecular phylogenetic relationship in perennial and annualAveneae. The results suggest unexpectedly close affinities of the agronomically important genusAvena to comparatively small-flowered taxa ofAveneae. GenusArrhenatherum and small-flowered subgenera ofHelictotrichon are close extant relatives. The large genusHelictotrichon is para- if not polyphyletic, only its subgenera are monophyletic.Trisetum is clearly separated fromHelictotrichon and forms together withKoeleria and perhaps others a monophyletic lineage which is characterised by a conspicuous 9-bp deletion in ITS1. The impact of the ITS data on the delineation of some genera and subtribes ofAveneae and on the recognition of their biogeographical and ecological patterns is outlined.  相似文献   

10.
Switches in pollinators have been argued to be key drivers of floral evolution in angiosperms. However, few studies have tested the relationship between floral shape evolution and switches in pollination in large clades. In concert with a dated phylogeny, we present a morphometric analysis of corolla, anther connective, and style shape across 44% of nearly 1000 species of Salvia (Lamiaceae) and test four hypotheses of floral evolution. We demonstrate that floral morphospace of New World (NW) Salvia is largely distinct from that of Old World (OW) Salvia and that these differences are pollinator driven; shifts in floral morphology sometimes mirror shifts in pollinators; anther connectives (key constituents of the Salvia staminal lever) and styles co-evolved from curved to linear shapes following shifts from bee to bird pollination; and morphological differences between NW and OW bee flowers are partly the legacy of constraints imposed by an earlier shift to bird pollination in the NW. The distinctive staminal lever in Salvia is a morphologically diverse structure that has evolved in concert with both the corolla and style, under different pollinator pressures, and in contingent fashion.  相似文献   

11.
Eight hepatitis B virus (HBV) isolates of genotype G were recovered from patients and sequenced over the entire genome. Six of them had a genomic length of 3,248 bp and two had genomic lengths of 3,239 bp (USG15) and 3,113 bp (USG18) due to deletions. The 10 HBV/G isolates, including the 8 sequenced isolates as well as the original isolate (AF160501) and another isolate (B1-89), had a close sequence homology of 99.3 to 99.8% among themselves (excluding USG18 with a long deletion) but of <88.7% to any of the 68 HBV isolates of the other six genotypes with the full-length sequence known. The eight HBV/G isolates possessed an insertion of 36 bp in the core gene and two stop codons in the precore region, as did the AF160501 and B1-89 isolates. The 10 HBV/G isolates clustered on a branch separate from those bearing the other six genotypes (A through F [A-F]) in the phylogenetic tree constructed from full-length sequences of 78 HBV isolates as well as in those constructed from the core, polymerase, X, and envelope genes. Despite two stop codons in the precore region that prohibited the translation of the HBV e antigen (HBeAg), all of the eight patients with HBV/G infection possessed the HBeAg in serum. By restriction fragment length polymorphism of the surface gene, all of the eight patients were found to be coinfected with HBV of genotype A (HBV/A), which would be responsible for the expression of HBeAg in them. It is worthy of examination to determine how coinfection occurs and whether HBV/G needs HBV/A for replication.  相似文献   

12.
Genetic variation detected by protein electrophoresis at 41 presumptive gene loci was assayed in four populations of Gyps africanus and compared to values previously obtained for Gyps coprotheres. Values calculated for percentage of polymorphic loci (P=34.15%, 0.99 criterion) and average heterozygosity (&Hmacr;=0.108, +/-0.032) in G. africanus, confirm low levels of genetic variation as reported for G. coprotheres. Allele frequency data, assessed at 19 loci, were obtained to evaluate genetic differentiation among four vulture species. Six (31.58%) of the 19 shared loci were polymorphic. Values of 1.26 (+/-0.1), 26.32% and 0.076 (+/-0.047) for G. africanus, 1.21 (+/-0.1), 21.05% and 0.097 (+/-0.045) for Torgos tracheliotus, 1.11 (+/-0.7), 21.05% and 0.053 (+/-0.053) for Neophron percnopterus and 1.05 (+/-0.5), 5.26% and 0.044 (+/-0.047) for G. coprotheres were obtained for the mean number of alleles per locus, P and &Hmacr;, respectively. An average between-population fixation index (F(ST)) value of 0.322 was obtained, which is indicative of significant (P<0.01) differentiation between the four accipitrid species studied. Considerable concordance was obtained between dendograms produced from different analyses, pointing to the distinctiveness of N. percnopterus, which has evolved along a separate lineage as G. africanus, G. coprotheres and T. tracheliotus. Along the latter lineage G. africanus is clustered together with G. coprotheres which is consistent with the morphological similarities of these species.  相似文献   

13.
14.
Ranunculus is a large genus with a worldwide distribution. Phylogenetic analyses of c. 200 species of Ranunculus s.l. based on sequences of the nrITS using maximum parsimony and Bayesian inference yielded high congruence with previous cpDNA restriction site analyses, but strongly contradict previous classifications. A large core clade including Ranunculus subg. Ranunculus, subg. Batrachium, subg. Crymodes p.p., Ceratocephala, Myosurus, and Aphanostemma is separated from R. subg. Ficaria, subg. Pallasiantha, subg. Coptidium, subg. Crymodes p.p., Halerpestes, Peltocalathos, Callianthemoides, and Arcteranthis. Within the core clade, 19 clades can be described with morphological and karyological features. Several sections are not monophyletic. Parallel evolution of morphological characters in adaptation to climatic conditions may be a reason for incongruence of molecular data and morphology-based classifications. In some mountainous regions, groups of closely related species may have originated from adaptive radiation and rapid speciation. Split decomposition analysis indicated complex patterns of relationship and suggested hybridization in the apomictic R. auricomus complex, R. subg. Batrachium, and the white-flowering European alpines. The evolutionary success of the genus might be due to a combination of morphological plasticity and adaptations, hybridization and polyploidy as important factors for regional diversification, and a broad range of reproductive strategies.  相似文献   

15.
A combined data set of nuclear SSU rDNA, LSU rDNA, and mitochondrial SSU rDNA sequences was analyzed in order to examine the relationships of the major clades of euascomycetes. Partial sequences of 14 ascomycetes were determined and aligned with the corresponding sequences of 16 other ascomycetes retrieved from Genbank. The alignment was analyzed using maximum parsimony (MP) and a Bayesian analysis with Markov chain Monte Carlo (B/MCMC). The classification based on single-gene studies is supported, but the confidence is enhanced in the concatenated analysis. The monophyly of the superclass Leotiomyceta, which includes all euascomycetes with inoperculate asci, is strongly supported. The polyphyly of ascolocularous fungi is supported. The group is divided into two groups: the Dothideomycetes basal to all other Leotiomyceta and the Chaetothyriomycetes as sister-group to Eurotiomycetes. The Lecanoromycetes appear as a monophyletic group with strong support and form a sister-group to the Chaetothyriomycetes/Eurotiomycetes clade, but this lacks support. The Leotiomycetes and Sordariomycetes form a strongly supported sister-group. Alternative topologies are tested using parametric bootstrapping; a basal position of the Eurotiomycetes and Leotiomycetes in the Leotiomyceta cannot be rejected, while such a position can be rejected for Chaetothyriomycetes, Lecanoromycetes and Sordariomycetes. The character evolution with regard to ascoma type, ascus type and ascoma-ontogeny is examined using MP and maximum likelihood (ML). While it appears most likely that the ancestor of the inoperculate ascomycetes had apothecia and an ascohymenial ascoma-ontogeny using MP methods, the ML approach shows that there is some uncertainty at the current state of knowledge. The improvement of confidence of the combined data set in comparison with single-gene studies makes us confident that analyses with additional data sets will further improve the confidence and eventually uncover the branching order of euascomycetes.  相似文献   

16.
In order to determine an unknown fish population from the Vrana Lake, mitochondrial cytochrome b gene and non-coding nuclear region Cyfun P were investigated. Stabile population of Bulldog rudd, Scardinius dergle Heckel & Kner, the endemic Croatian freshwater fish in the Krka River, was genetically characterized with the same markers in order to compare it with the material from the Vrana Lake. Genetic markers were sequenced and aligned with the similar ones obtained from the GenBank in order to determine taxonomic and phylogenetic position of these two species. A significant discrepancy between nuclear genetic markers of our specimens and the sequence from the GenBank was found. Phylogenetic analysis suggested that the specimens from the Vrana Lake belong to the species S. hesperidicus. Morphometric characteristics, the maximum length and body mass showed new maximum values for both S. dergle and S. hesperidicus.  相似文献   

17.
The great majority of the Procamallaninae occur in teleosts from tropical regions; however, representatives of this group are also frequent parasites of aquatic clawed toads (Xenopus spp.) in Africa. The taxonomic status of procamallanines from different Xenopus spp. and their geographical distribution is reviewed. Batrachocamallanus n. g. is created to include forms from amphibians with large numbers of mucrons on the female tail and relatively small body size. B. occidentalis n. sp. and B. siluranae n. sp. are described, while Procamallanus brevis Kung, 1948, originally recorded from an unidentified African amphibian, is considered a synonym of B. slomei (Southwell & Kirshner, 1937) n. comb. Due to the presence of spiral thickenings on its buccal capsule, B. xenopodis (Baylis, 1929) n. comb. has previously been placed in the genus Spirocamallanus Olsen, 1952. However, this species shares the apomorphic presence of numerous mucrons on the female tail, and almost identical cephalic morphology, male caudal structures and female reproductive system with other procamallanines from clawed toads. This suggests that they represent a monophyletic grouping. There is also only limited morphometric differentiation between B. xenopodis and the other proposed representatives of Batrachocamallanus (supported by a multivariate analysis of male and female specimens), which further indicates a close relationship between them. Great variability in the presence and type of buccal capsule thickenings occurs within Batrachocamallanus. Members of this genus most closely resemble the African species Procamallanus laeviconchus (Wedl, 1862), which exhibits a smooth buccal capsule similar to that of B. siluranae. Buccal capsule thickenings of the remaining Batrachocamallanus spp. probably arose independently from those described in other procamallanines. Such characters may be evolutionarily unstable and an unsuitable basis for generic classification in this subfamily. Although B. siluranae is the only Batrachocamallanus species to occur in X. tropicalis-like hosts (which represent a separate lineage from other clawed toads), its distribution, and that of its congeners, may be determined more by host-independent ecological or biogeographical factors than by an association with host phylogeny. Thus, B siluranae occurs in Xenopus spp. from tropical rain forest (including those from other host lineages) while the other forms are typically found in savanna or montane forest, and in the cases of B. slomei and B. xenopodis at least, do not show narrow host specificity to particular clawed toad taxa. Although more than one Batrachocamallanus spp. were found in X. laevis, X. muelleri and X. fraseri-like clawed toads, co-existence at the same locality never occurred, perhaps indicating a high degree of interspecific ecological segregation.  相似文献   

18.
The diversity of phenotypically different and often reproductively isolated lacustrine forms of charrs of the genus Salvelinus represents a substantial problem for taxonomists and evolutionary biologists. Based on the analysis of variability of ten microsatellite loci and two fragments of mitochondrial DNA (control region and cyt‐b gene), the evolutionary history of three charr species from Lake El'gygytgyn was reconstructed, and phylogenetic relationships between the main representatives of the genus were revealed. Three species from Lake El'gygytgyn were strongly reproductively isolated. Long‐finned charr described previously as Salvethymus svetovidovi, an ancient endemic form in the lake, originated 3.5 Mya (95% Bayesian credible intervals: 1.7, 6.1). Placement of this species in the phylogenetic tree of Salvelinus was not determined strictly, but it should be located in the basal part of the clade Salvelinus alpinus – S. malma species complex. The origin of small‐mouth charr S. elgyticus and Boganida charr S. boganidae in Lake El'gygytgyn was related to allopatric speciation. Their ancestors were represented by two glacial lineages of Taranets charr S. alpinus taranetzi from Asia. In Lake El'gygytgyn, these lineages entered into secondary contact postglacially. A revision of the main phylogenetic groups within the Salvelinus alpinus – S. malma complex is conducted. The Boganida charrs from Lakes El'gygytgyn and Lama (Taimyr) belong to different phylogenetic groups of Arctic charr and should not be regarded as a single species S. boganidae. Using the charrs from Lakes El'gygytgyn and Lama as a case study, we show that a model of sympatric speciation, which seemed more probable based on previous empirical evidence, was rejected by other data.  相似文献   

19.
Molecular (mitochondrial cytochrome C oxidase subunit 1– COI) analysis was performed to characterize the poorly known Malapterurus minjiriya from Nigerian inland water bodies. Integrative taxonomy, involving morphological and molecular data, confirms the identity of M. minjiriya. Matrilineal genealogy reveals a sister relationship of M. minjiriya with Malapterurus electricus and Malapterurus microstoma. The genetic analysis further shows evidence of population divergence within M. electricus and Malapterurus beninensis. The findings of the study highlight the importance of the integration of DNA barcoding in biodiversity documentation of freshwater fish species in Nigeria.  相似文献   

20.
【目的】本研究旨在揭示河南省不同地区棉蚜Aphis gossypii种群共生菌Wolbachia的感染情况,明确Wolbachia的感染类型及分类地位。【方法】2016-2017年间采集河南省不同地区的13个棉蚜种群,通过扩增COI基因片段对其进行种类鉴定;通过扩增棉蚜种群中Wolbachia的wsp基因片段对其进行Wolbachia感染率的检测,应用neighbor-joining法构建系统进化树进行棉蚜种群中Wolbachia的系统发育分析。【结果】对河南省内不同地区采集的13个棉蚜种群的Wolbachia感染率而言,郑州(ZZ)种群最高(46.67%),信阳2(XY2)种群最低(6.67%),13个种群Wolbachia的感染率范围为6.67%~46.67%,平均感染率为28.35%。基于wsp基因构建的系统发育树表明,安阳和信阳的棉蚜种群感染的Wolbachia株系属于B大组,其余地区棉蚜种群感染的Wolbachia株系属于A大组。【结论】河南省不同地区的棉蚜种群Wolbachia感染率差别较大,且不同种群感染的Wolbachia株系分别属于A大组或B大组。  相似文献   

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