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1.
习欠云  王殉章 《昆虫知识》2010,47(6):1274-1279
水生肉食亚目(Hydradephaga)属于鞘翅目Coleoptera,是一类具有水生习性的食肉性真正水生甲虫(True water beetles)。在真正水生甲虫的系统分类中存在三种假说,一种是肉食亚目(Adephaga)位于该系统的基部,一种是多食亚目(Polyphaga)位于该系统基部,第三种是藻食亚目(Myxophaga)位于该系统基部。最近研究结果更多倾向第一种假说。目前水生肉食亚目大约有5 500个种,200多个属,含8个科。水生肉食亚目的科间水平系统发育关系虽被广泛研究,但观点仍不统一。有代表意义的有三个假说,一是豉甲科(Gyrinidae)位于系统基部,接下来是龙虱科(Dytiscidae)、两栖甲科(Amphizoidae)、水甲科(Hygrobiidae)、小粒龙虱科(Noteridae)与沼梭科(Haliplidae);二是沼梭科位于系统的基部;三是豉甲科位于系统的基部,接下来是沼梭科和龙虱总科(Dytiscoidea),其中龙虱总科由两栖甲科、水甲科、龙虱科、小粒龙虱科组成。目前根据形态学的分类,并结合分子系统学研究方法,第三种假说更符合水生肉食亚目的系统分类,也支持了水生肉食亚目作为一个单系,其祖先来自陆生的假说。  相似文献   

2.
The analysis of ancient DNA (aDNA) provides archaeologists and anthropologists with innovative, scientific and accurate data to study and understand the past. In this work, ancient seeds, found in the "Mora Cavorso" archaeological site (Latium, Central Italy), were analyzed to increase information about Italian Neolithic populations (plant use, agriculture, diet, trades, customs and ecology). We performed morphological and genetic techniques to identify fossil botanical species. In particular, this study also suggests and emphasizes the use of DNA barcode method for ancient plant sample analysis. Scanning electron microscope (SEM) observations showed seed compact structure and irregular surface but they did not permit a precise nor empirical classification: so, a molecular approach was necessary. DNA was extracted from ancient seeds and then it was used, as template, for PCR amplifications of standardized barcode genes. Although aDNA could be highly degraded by the time, successful PCR products were obtained, sequenced and compared to nucleotide sequence databases. Positive outcomes (supported by morphological comparison with modern seeds, geographical distribution and historical data) indicated that seeds could be identified as belonging to two plant species: Olea europaea L. and Cornus mas L.  相似文献   

3.
Because of their role in causing schistosomiasis, flukes of the genus Schistosoma are the best known of all digeneans. The genus has traditionally been divided into four familiar species groups. Here we report on three poorly known species of Schistosoma, one of which, Schistosoma hippopotami, is known from the hippopotamus, one of which is provisionally identified as Schistosoma edwardiense, another hippo parasite, and a third that has not previously been described. All were collected from freshwater snails obtained from Lake Edward, western Uganda, the type locality for both known hippo schistosomes. The three different kinds of schistosome cercariae differ from one another in size, and all are readily differentiated by their long tail stems from the cercariae of human-infecting species. Furthermore, each was recovered from a different genus of snail host, Biomphalaria sudanica, Bulinus truncatus or Ceratophallus natalensis. Molecular analysis, based on 8350 bases of combined nuclear and mitochondrial DNA, groups these three long tail-stem cercariae into a well supported clade that does not associate with any of the recognised species groups. The placement of this clade, basal to all African species plus several Asian species, suggests that there has been an ancient association between Schistosoma and hippos. This new African Schistosoma clade advocates the need for further modification of the traditional species group-based classification. Two of the four species groups are paraphyletic. It also suggests that Schistosoma has been remarkably plastic with respect to adapting to snail hosts-three distantly related genera of planorbid snails have been exploited by worms within a single clade. Finally, it adds a new layer of complexity to deciphering the origins of Schistosoma, often considered to be African but recently challenged as being Asian. In the late Cenozoic the distribution of hippo species straddled both Africa and Asia and they may have provided a means for the introduction of blood flukes to Africa.  相似文献   

4.
Although Africa harbors low species diversity compared to the neotropics or South East Asia, the African fern flora is of interest because of its specific composition and geographic location between the neotropics and Asia. We address the question of how the evolution of the African fern flora may have been enriched by repeated input from the neotropics and Asia. For the purpose of this paper we consider ihree major biogeographic regions: the neotropics, Africa and Madagascar, and Asia including Malesia and Australasia. We interpret distribution data for six clades of Polypodiaceae in a molecular phylogenetic framework. We conclude that African fern taxa shared with or closely related to ones in the neotropics or Asia have been brought about by ancient and recent dispersal events with or without subsequent speciation. The African fern flora is interpreted as being composed of endemic, neotropical, and Asian elements and as being situated in a zone of overlap of typical neotropical and Asian fern floras.  相似文献   

5.
Testate amoebae are amoeboid protists inhabiting a test (shell). They occur globally in soils, wetlands and freshwater, especially peats and mosses. They are of ancient origin, dating from at least the Mesozoic, with possible ancestors as old as the Neoproterozoic. Approximately 2,000 taxa have been described—a number which could easily rise to 4,000 with comprehensive recording. Whilst many protists appear to be cosmopolitan as morphospecies, some of the larger testate species (exceeding 100 μm) have long been considered, controversially, to be geographically restricted. Definitive conclusions have often been confounded by gaps in distributional data and misidentification. Recent increases in recording from previously little known regions, and the rise of molecular taxonomy, have started to resolve outstanding issues—processes still far from complete. Accordingly, biogeographical studies have concentrated on “flagship” species—those which can be identified with certainty and are sufficiently recorded to determine their ecological ranges. Apodera vas (Certes) has been proved to be largely restricted to the Gondwanaland continents and sub-Antarctic islands, but absent from the Holartic despite the availability of much suitable habitat. An early analysis postulated a Mesozoic origin of the species and a distribution influenced by continental drift. Recent molecular evidence could imply a later origin. Either way, its current distribution is clearly influenced by the pattern of global wind currents and lack of lowland tropical habitat. By contrast a “Gondwana-tropical” group of species appears to be restricted to latitudes unaffected by glaciation. Instances of local endemism, such as restriction to a single island, are also known, which await molecular evidence for substantiation. Special Issue: Protist diversity and geographic distribution. Guest editor: W. Foissner.  相似文献   

6.
Whilst archaeological evidence for many aspects of life in ancient China is well studied, there has been much less interest in ancient infectious diseases, such as intestinal parasites in past Chinese populations. Here, we bring together evidence from mummies, ancient latrines, and pelvic soil from burials, dating from the Neolithic Period to the Qing Dynasty, in order to better understand the health of the past inhabitants of China and the diseases endemic in the region. Seven species of intestinal parasite have been identified, namely roundworm, whipworm, Chinese liver fluke, oriental schistosome, pinworm, Taenia sp. tapeworm, and the intestinal fluke Fasciolopsis buski. It was found that in the past, roundworm, whipworm, and Chinese liver fluke appear to have been much more common than the other species. While roundworm and whipworm remained common into the late 20th century, Chinese liver fluke seems to have undergone a marked decline in its prevalence over time. The iconic transport route known as the Silk Road has been shown to have acted as a vector for the transmission of ancient diseases, highlighted by the discovery of Chinese liver fluke in a 2,000 year-old relay station in northwest China, 1,500 km outside its endemic range.  相似文献   

7.
Porcini (Boletus section Boletus: Boletaceae: Boletineae: Boletales) are a conspicuous group of wild, edible mushrooms characterized by fleshy fruiting bodies with a poroid hymenophore that is "stuffed" with white hyphae when young. Their reported distribution is with ectomycorrhizal plants throughout the Northern Hemisphere. Little progress has been made on the systematics of this group using modern molecular phylogenetic tools because sampling has been limited primarily to European species and the genes employed were insufficient to resolve the phylogeny. We examined the evolutionary history of porcini by using a global geographic sampling of most known species, new discoveries from little explored areas, and multiple genes. We used 78 sequences from the fast-evolving nuclear internal transcribed spacers and are able to recognize 18 reciprocally monophyletic species. To address whether or not porcini form a monophyletic group, we compiled a broadly sampled dataset of 41 taxa, including other members of the Boletineae, and used separate and combined phylogenetic analysis of sequences from the nuclear large subunit ribosomal DNA, the largest subunit of RNA polymerase II, and the mitochondrial ATPase subunit six gene. Contrary to previous studies, our separate and combined phylogenetic analyses support the monophyly of porcini. We also report the discovery of two taxa that expand the known distribution of porcini to Australia and Thailand and have ancient phylogenetic connections to the rest of the group. A relaxed molecular clock analysis with these new taxa dates the origin of porcini to between 42 and 54 million years ago, coinciding with the initial diversification of angiosperms, during the Eocene epoch when the climate was warm and humid. These results reveal an unexpected diversity, distribution, and ancient origin of a group of commercially valuable mushrooms that may provide an economic incentive for conservation and support the hypothesis of a tropical origin of the ectomycorrhizal symbiosis.  相似文献   

8.
Bird migration is one of the most spectacular and best-studied phenomena in behavioural biology. Yet, while the patterns of variation in migratory behaviour and its ecological causes have been intensively studied, its genetic, physiological and neurological control remains poorly understood. The lack of knowledge of the molecular basis of migration is currently not only limiting our insight into the proximate control of migration, but also into its evolution. We investigated polymorphisms in the exons of six candidate genes for key behavioural traits potentially linked to migration, which had previously been identified in several bird species, and eight control loci in 14 populations of blackcaps (Sylvia atricapilla), representing the whole range of geographical variation in migration patterns found in this species, with the aim of identifying genes controlling variation in migration. We found a consistent association between a microsatellite polymorphism and migratory behaviour only at one candidate locus: the ADCYAP1 gene. This polymorphism explained about 2.6 per cent of the variation in migratory tendency among populations, and 2.7-3.5% of variation in migratory restlessness among individuals within two independent populations. In all tests, longer alleles were associated with higher migratory activity. The consistency of results among different populations and levels of analysis suggests that ADCYAP1 is one of the genes controlling the expression of migratory behaviour. Moreover, the multiple described functions of the gene product indicate that this gene might act at multiple levels modifying the shift between migratory and non-migratory states.  相似文献   

9.
An intraspecific study on Phlebotomus sergenti, the main and only proven vector of Leishmania tropica among the members of the subgenus Paraphlebotomus was performed. The internal transcribed spacer 2 (ITS2) sequences of 12 populations from 10 countries (Cyprus, Egypt, Italy, Lebanon, Morocco, Pakistan, Portugal, Spain, Syria, and Turkey) were compared. Samples also included three species closely related to P. sergenti: Phlebotomus similis (three populations from Greece and Malta), Phlebotomus jacusieli and Phlebotomus kazeruni. Our results confirm the validity of the taxa morphologically characterised, and imply the revision of their distribution areas, which are explained through biogeographical events. At the Miocene time, a migration route, north of the Paratethys sea would have been followed by P. similis to colonise the north of the Caucasus, Crimea, Balkans including Greece and its islands, and western Turkey. Phlebotomus sergenti would have followed an Asiatic dispersion as well as a western migration route south of the Tethys sea to colonise North Africa and western Europe. This hypothesis seems to be well supported by high degree of variation observed in the present study, which is not related to colonisation or to intra-populational variation. Two groups can be individualised, one oriental and one western in connection with ecology, host preferences and distribution of L. tropica. We hypothesise that they could be correlated with differences in vectorial capacities.  相似文献   

10.
Enterobius vermicularis, pinworm, is one of the most common helminths worldwide, infecting nearly a billion people at all socio-economic levels. In prehistoric populations the paleoparasitological findings show a pinworm homogeneous distribution among hunter-gatherers in North America, intensified with the advent of agriculture. This same increase also occurred in the transition from nomad hunter-gatherers to sedentary farmers in South America, although E. vermicularis infection encompasses only the ancient Andean peoples, with no record among the pre-Colombian populations in the South American lowlands. However, the outline of pinworm paleoepidemiology has been supported by microscopic finding of eggs recovered from coprolites. Since molecular techniques are precise and sensitive in detecting pathogen ancient DNA (aDNA), and also could provide insights into the parasite evolutionary history, in this work we have performed a molecular paleoparasitological study of E. vermicularis. aDNA was recovered and pinworm 5S rRNA spacer sequences were determined from pre-Columbian coprolites (4110 BC-AD 900) from four different North and South American archaeological sites. The sequence analysis confirmed E. vermicularis identity and revealed a similarity among ancient and modern sequences. Moreover, polymorphisms were identified at the relative positions 160, 173 and 180, in independent coprolite samples from Tulán, San Pedro de Atacama, Chile (1080-950 BC). We also verified the presence of peculiarities (Splicing leader (SL1) RNA sequence, spliced donor site, the Sm antigen biding site, and RNA secondary structure) which characterise the SL1 RNA gene. The analysis shows that the SL1 RNA gene of contemporary pinworms was present in pre-Columbian E. vermicularis by 6110 years ago. We were successful in detecting E. vermicularis aDNA even in coprolites without direct microscopic evidence of the eggs, improving the diagnosis of helminth infections in the past and further pinworm paleoepidemiological studies.  相似文献   

11.
Discovery of Aspidytidae,a new family of aquatic Coleoptera   总被引:7,自引:0,他引:7  
The six extant aquatic families of Hydradephaga (Coleoptera) known so far represent a diverse group of beetles morphologically highly modified for life in the water. We report the discovery of a new genus with two species from South Africa and China, which differ greatly from all extant families, but resemble the Jurassic-Cretaceous dagger Liadytidae (the dagger symbol indicates that the taxa are known only as fossils). Based on a combined phylogenetic analysis of molecular and morphological data we erect a new family, Aspidytidae, which is the sister group of Dytiscidae plus Hygrobiidae. We propose a new scenario for the evolution of swimming behaviour in adephagan beetles, in which the transition into the aquatic environment is followed by complex and repeated changes in lifestyles, including the secondary complete loss of swimming ability in Aspidytidae.  相似文献   

12.
Partamona mulata is a stingless bee species endemic to cerrado, a severely threatened phytogeographical domain. Clearing for pasture without proper soil treatment in the cerrado facilitates the proliferation of termite ground nests, which are the nesting sites for P. mulata. The genetic consequences of these changes in the cerrado environment for bee populations are still understudied. In this work, we analyzed the genetic diversity of 48 colonies of P. mulata collected throughout the species’ distribution range by sequencing two mitochondrial genes, cytochrome oxidase I and cytochrome B. A very low polymorphism rate was observed when compared to another Partamona species from the Atlantic forest. Exclusive haplotypes were observed in two of the five areas sampled. The sharing of two haplotypes between collection sites separated by a distance greater than the flight range of queens indicates an ancient distribution for these haplotypes. The low haplotype and nucleotide diversity observed here suggests that P. mulata is either a young species or one that has been through population bottlenecks. Locally predominant and exclusive haplotypes (H2 and H4) may have been derived from local remnants through cerrado deforestation and the expansion of a few colonies with abundant nesting sites.  相似文献   

13.
Question: Do tree species, with different litter qualities, affect the within‐forest distribution of forest understorey species on intermediate to base‐rich soils? Since habitat loss and fragmentation have caused ancient forest species to decline, those species are the main focus of this study. Location: Three ancient forests, along a soil gradient from acidification‐sensitive to base‐rich, were studied: Limbrichterbosch and Savelsbos in The Netherlands and Holtkrat in Denmark. Methods: Canopy and soil surveys along transects generated data for Redundancy Analysis on tree – humus relationships. We analysed the distribution of forest plant species with Canonical Correspondence Analysis. The explanatory factors were soil characteristics (pH, organic matter, loam content and thickness of the humus layers), external crown projection, ground water and canopy data. We further analysed the relationship between forest species and humus characteristics with Spearman correlations. Results: Tree species have a significant impact on humus characteristics through the nature of their litter. Humus characteristics significantly explain the distribution of forest understorey species. The pH of the first 25 cm mineral soil and the thickness of the F‐ (fermentation) layer are the primary factors affecting the distribution of ancient forest species. Conclusion: This study indicates that the species composition of the forest canopy affects the distribution of forest understorey species. Ancient forest species are more abundant and frequent underneath trees with base‐rich litter. On acidification‐sensitive soils these relationships were stronger than on more base‐rich, loamy soils.  相似文献   

14.
Recently, the study of ancient DNA (aDNA) has been greatly enhanced by the development of second-generation DNA sequencing technologies and targeted enrichment strategies. These developments have allowed the recovery of several complete ancient genomes, a result that would have been considered virtually impossible only a decade ago. Prior to these developments, aDNA research was largely focused on the recovery of short DNA sequences and their use in the study of phylogenetic relationships, molecular rates, species identification and population structure. However, it is now possible to sequence a large number of modern and ancient complete genomes from a single species and thereby study the genomic patterns of evolutionary change over time. Such a study would herald the beginnings of ancient population genomics and its use in the study of evolution. Species that are amenable to such large-scale studies warrant increased research effort. We report here progress on a population genomic study of the Adélie penguin (Pygoscelis adeliae). This species is ideally suited to ancient population genomic research because both modern and ancient samples are abundant in the permafrost conditions of Antarctica. This species will enable us to directly address many of the fundamental questions in ecology and evolution.  相似文献   

15.
The diversity of Bt resistance genes in species of Lepidoptera   总被引:5,自引:0,他引:5  
Although the mode of action of Cry1A toxins produced by Bacillus thuringiensis is fairly well understood, knowledge of the molecular mechanisms by which lepidopteran species have evolved resistance to them is still in its infancy. The most common type of resistance has been called "Mode 1" and is characterized by recessive inheritance, >500-fold resistance to and reduced binding by at least one Cry1A toxin, and negligible cross-resistance to Cry1C. In three lepidopteran species, Heliothis virescens, Pectinophora gossypiella, and Helicoverpa armigera, Mode 1 resistance is caused by mutations in a toxin-binding 12-cadherin-domain protein expressed in the larval midgut. These mutations all interrupt the primary sequence of the protein and prevent its normal localization in the membrane, presumably removing a major toxic binding target of the Cry1A toxins. In Plutella xylostella, however, Mode 1 resistance appears to be caused by a different genetic mechanism, as Cry1A resistance is unlinked to the cadherin gene. Mapping studies in H. virescens have detected an additional major Cry1A resistance gene, which on the basis of comparative linkage mapping is distinct from the one in P. xylostella. An additional resistance mechanism supported by genetic data involves a protoxin-processing protease in Plodia interpunctella, and this is likely to be different from the genes mapped in Plutella and Heliothis. Thus, resistance to Cry1A toxins in species of Lepidoptera has a complex genetic basis, with at least four distinct, major resistance genes of which three are mapped in one or more species. The connection between resistance genes and the mechanisms they encode remains a challenging task to elucidate.  相似文献   

16.
17.
With ancient DNA technology, DNA sequences have been added to the list of characters available to infer the phyletic position of extinct species in evolutionary trees. We have sequenced the entire 12S rRNA and partial cytochrome b (cyt b) genes of one 60-70,000-year-old sample, and partial 12S rRNA and cyt b sequences of two 40-45,000-year-old samples of the extinct woolly rhinoceros (Coelodonta antiquitatis). Based on these two mitochondrial markers, phylogenetic analyses show that C. antiquitatis is most closely related to one of the three extant Asian rhinoceros species, Dicerorhinus sumatrensis. Calculations based on a molecular clock suggest that the lineage leading to C. antiquitatis and D. sumatrensis diverged in the Oligocene, 21-26 MYA. Both results agree with morphological models deduced from palaeontological data. Nuclear inserts of mitochondrial DNA were identified in the ancient specimens. These data should encourage the use of nuclear DNA in future ancient DNA studies. It also further establishes that the degraded nature of ancient DNA does not completely protect ancient DNA studies based on mitochondrial data from the problems associated with nuclear inserts.  相似文献   

18.
The superfamily Dytiscoidea contains six families with an aquatic lifestyle, with most of its extant diversity in two families: the burrowing water beetles (Noteridae) and the diving beetles (Dytiscidae). The other families have few species (up to six) and generally highly disjunct extant distributions. Aspidytidae currently contains one genus with two species, one in China and one in South Africa. Here we provide the first molecular data for the Chinese species, allowing us to explore the phylogenetic relationships and position of both species of this small family for the first time. Based on a matrix of 11 genes we inferred a phylogenetic hypothesis for Dytiscoidea including all extant families. Unexpectedly, Aspidytidae were consistently recovered as paraphyletic relative to Amphizoidae, despite being well characterized by apparently synapomorphic adult features. A re‐examination of larval characters in the two aspidytid species revealed that the larva of the Chinese species is strikingly similar to that of Amphizoidae. Both share a series of plesiomorphic features but also some potential synapomorphies, including a dense vestiture of short setae on the head capsule, anteriorly shifted posterior tentorial grooves and widely separated labial palps. Arguably these features may belong to the groundplan of the clade Aspidytidae + Amphizoidae, with far‐reaching secondary modifications (including reversals) in the South African Aspidytes niobe. At present we retain the family Aspidytidae, however, due to the strong adult morphological synapomorphies of the two extant species, and the fact that the molecular paraphyly of the family may result from the highly divergent nature of the two extant species. This long evolutionary separation and strong divergence, in terms of gene sequences and larval features, is undeniable, substantial levels of saturation in third codon positions of protein‐coding genes being present between the two taxa. We address this issue taxonomically by introducing the new genus S inaspidytes gen. nov. for the Chinese Aspidytes wrasei. The continued contentious relationships amongst Dytiscidae, Hygrobiidae, Aspidytidae and Amphizoidae highlight the need for more data to address dytiscoid phylogenetics, possibly involving a genomic approach. © 2016 The Linnean Society of London  相似文献   

19.
Characters of the newly discovered larvae of the South African Cliff Water Beetle Aspidytes niobe were examined and integrated into a data matrix including all families of Dytiscoidea as well as Haliplidae. Fifty-three morphological characters of adults and larvae were analysed separately and combined with molecular data from six nuclear and mitochondrial genes. The phylogeny of the group is reconstructed for the study of the evolution of swimming behaviour and larval feeding habits, as well as the shift in diversification rates leading to the two most speciose lineages. The parsimony analysis of all equally weighted morphological and molecular characters combined resulted in a single well supported tree with the topology (Noteridae (Hygrobiidae ((Aspidytidae, Amphizoidae) Dytiscidae))), in agreement with the molecular data alone, but in contradiction to the morphological data, which favoured a topology in which Hygrobiidae is sister to Dytiscidae. The exclusion of third codon positions of the three protein coding genes resulted in a topology identical to that obtained with the morphological data alone, but the use of Bayesian probabilities or the amino acid sequence resulted in the same topology as that of the tree obtained with parsimony using all equally weighted characters. We concluded that interactions of third codon positions with the other data are complex, and their removal is not justified. There was a significant increase in the diversification rate at the base of the richest families (Noteridae and Dytiscidae), which could be associated with the development of simultaneous stroke and higher swimming performance, although data on the swimming behaviour of some basal groups of Noteridae are incomplete. The presence of larval mandibular sucking channels may have contributed to the diversification of Dytiscidae and the species-rich noterid genera Hydrocanthus and Canthydrus .  相似文献   

20.
Eighteen of the 34 species of the fan palm genus Livistona (Arecaceae) are restricted to Australia and southern New Guinea, east of Wallace’s Line, an ancient biogeographic boundary between the former supercontinents Laurasia and Gondwana. The remaining species extend from SE Asia to Africa, west of Wallace’s Line. Competing hypotheses contend that Livistona is (a) ancient, its current distribution a relict of the supercontinents, or (b) a Miocene immigrant from the north into Australia as it drifted towards Asia. We have tested these hypotheses using Bayesian and penalized likelihood molecular dating based on 4 Kb of nuclear and chloroplast DNA sequences with multiple fossil calibration points. Ancestral areas and biomes were reconstructed using parsimony and maximum likelihood. We found strong support for the second hypothesis, that a single Livistona ancestor colonized Australia from the north about 10–17 Ma. Spread and diversification of the genus within Australia was likely favoured by a transition from the aseasonal wet to monsoonal biome, to which it could have been preadapted by fire-tolerance.  相似文献   

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