Coevolution between Lamellodiscus (Monogenea: Diplectanidae) and Sparidae (Teleostei): the study of a complex host-parasite system

Abstract.— Host-parasite coevolution was studied between Sparidae (Teleostei) fishes and their parasites of the genus Lamellodiscus (Monogenea, Diplectanidae) in the northwestern Mediterranean Sea. Molecular phylogenies were reconstructed for both groups. The phylogenetic tree of the Sparidae was obtained from previously published 16S mitochondrial DNA (mtDNA) sequences associated with new cytochrome-b mtDNA sequences via a "total evidence" procedure. The phylogeny of Lamellodiscus species was reconstructed from 18S rDNA sequences that we obtained. Host-parasite coevolution was studied through different methods: TreeFitter, TreeMap, and a new method, ParaFit. If the cost of a host switch is not assumed to be high for parasites, all methods agree on the absence of widespread cospeciation processes in this host-parasite system. Host-parasite associations were interpreted to be due more to ecological factors than to coevolutionary processes. Host specificity appeared not to be related to host-parasite cospeciation.     

Evolutionary relationships of sibling tapeworm species (Cestoda) parasitizing teleost fishes

DNA/DNA hybridization and sequencing of rDNA (partial 18S rDNA and ITS1) were used to investigate phylogenetic relationships among seven host-specific Bothriocephalus parasites (Cestoda, Pseudophyllidae). The small nucleotide divergence between six of the seven bothriocephalids suggests that isolation and differentiation of Bothriocephalus lineages in the different host species probably occurred recently and over a short time span. Comparison of the molecular phylogeny of the parasite species to the phylogeny of their hosts (teleostean fishes) revealed little congruence between the branching patterns of hosts and parasites, suggesting that bothriocephalids have not cospeciated with their hosts.      

中国野生稻及栽培稻核糖体DNA第一转录间隔区序列分析及其系统学意义

用 PCR技术从产于我国的 3种野生稻和亚洲栽培稻的 2个亚种中特异地扩增和测序了 r DNA的第一转录间隔区。普通野生稻 (Oryza rufipogon)、药用野生稻 (O.officinalis)、疣粒野生稻 (O.granu-lata)和栽培稻的两个亚种 (O.sativa ssp.indica,O.sativa ssp.japonica)的 ITS1序列为 1 93bp、1 94bp、2 1 8bp、1 94bp和 1 94bp,它们的 G/ C含量为 69.3%～ 72 .7% ,序列中位点趋异率为 1 .5%～ 1 0 .6%。序列的相似性比较和简约性分支分析的结果表明 ,普通野生稻与栽培稻的两个亚种之间的亲缘关系最为密切 ;药用野生稻与普通野生稻和与栽培稻的两个亚种的相似性都为 82 % ,说明它与 AA基因组有一定的亲缘关系 ;疣粒野生稻与普通野生稻、药用野生稻和栽培稻两个亚种的亲缘关系相对较远 ,它在稻属中可能是一个系统地位较独特的类群。以 ITS1序列构建的 3种野生稻和 2个栽培稻亚种的系统发育关系与前人用同工酶、叶绿体 DNA、线粒体 DNA和核 DNA资料重建的稻属的系统发育关系基本一致     

Cryptic diversity of the symbiotic cyanobacterium Synechococcus spongiarum among sponge hosts

Cyanobacteria are common members of sponge-associated bacterial communities and are particularly abundant symbionts of coral reef sponges. The unicellular cyanobacterium Synechococcus spongiarum is the most prevalent photosynthetic symbiont in marine sponges and inhabits taxonomically diverse hosts from tropical and temperate reefs worldwide. Despite the global distribution of S. spongiarum , molecular analyses report low levels of genetic divergence among 16S ribosomal RNA (rRNA) gene sequences from diverse sponge hosts, resulting either from the widespread dispersal ability of these symbionts or the low phylogenetic resolution of a conserved molecular marker. Partial 16S rRNA and entire 16S–23S rRNA internal transcribed spacer (ITS) genes were sequenced from cyanobacteria inhabiting 32 sponges (representing 18 species, six families and four orders) from six geographical regions. ITS phylogenies revealed 12 distinct clades of S. spongiarum that displayed 9% mean sequence divergence among clades and less than 1% sequence divergence within clades. Symbiont clades ranged in specificity from generalists to specialists, with most (10 of 12) clades detected in one or several closely related hosts. Although multiple symbiont clades inhabited some host sponges, symbiont communities appear to be structured by both geography and host phylogeny. In contrast, 16S rRNA sequences were highly conserved, exhibiting less than 1% sequence divergence among symbiont clades. ITS gene sequences displayed much higher variability than 16S rRNA sequences, highlighting the utility of ITS sequences in determining the genetic diversity and host specificity of S. spongiarum populations among reef sponges. The genetic diversity of S. spongiarum revealed by ITS sequences may be correlated with different physiological capabilities and environmental preferences that may generate variable host–symbiont interactions.     

Patterns of association between crucifers and their flower-mimic pathogens: host jumps are more common than coevolution or cospeciation

Morphological and molecular phylogenies of animal parasites have often shown parallel cladogenesis, supporting hypotheses of coevolution. Few studies of the phylogenetic history for plants and their pathogens exist. Gene-for-gene interactions suggest that plant pathogens ought to have similar phylogenetic histories as their hosts. However, high dispersability combined with an inability to choose to leave if an inappropriate host has been landed on could increase the likelihood of host jumps and thus decrease phylogenetic congruence between plant pathogens and their hosts. In this study, I examined the pattern of association between the flower-mimicking crucifer rusts and their hosts by comparing independent host phylogenies (based on both cpDNA trnL-F introns and nuclear internal transcribed spacer [ITS] sequences) with that of their rust pathogens (based on ITS sequences). The expectation was that if the pathogens coevolved or cospeciated with their hosts, then their phylogenies should be congruent. Host-tracking coevolution can be differentiated from cospeciation by examining the times of divergence: If the pathogens are younger than the hosts, then it is likely that host tracking has occurred. For the crucifer rusts and their hosts, there was little evidence of parallel cladogenesis, suggesting that both cospeciation and coevolutionary tracking are rare. Instead, the most common pattern was one of host jumps to geographically associated taxa. There are at least three factors that may have contributed to the geographic structuring of the data. First, along the east-west transect stretching from the Rocky Mountains to California, large differences in rainfall and the timing of rainfall may reduce long-distance gene flow. Second, although dispersal of infectious spores is by wind, sexual reproduction of these fungi depends on insects, which move short distances. Third, host shifts are most likely to occur to geographically available taxa. Any species that grows adjacent to infected plants will be exposed to millions of spores, and the probability of eventual infection by a new mutant increases with greater exposure. Thus, patterns of association between the crucifers and their flower-mimic pathogens reflect jumps to geographically available hosts, which are not necessarily those that are most closely related.     

Migratory behavior of birds affects their coevolutionary relationship with blood parasites

Host traits, such as migratory behavior, could facilitate the dispersal of disease-causing parasites, potentially leading to the transfer of infections both across geographic areas and between host species. There is, however, little quantitative information on whether variation in such host attributes does indeed affect the evolutionary outcome of host-parasite associations. Here, we employ Leucocytozoon blood parasites of birds, a group of parasites closely related to avian malaria, to study host-parasite coevolution in relation to host behavior using a phylogenetic comparative approach. We reconstruct the molecular phylogenies of both the hosts and parasites and use cophylogenetic tools to assess whether each host-parasite association contributes significantly to the overall congruence between the two phylogenies. We find evidence for a significant fit between host and parasite phylogenies in this system, but show that this is due only to associations between nonmigrant parasites and their hosts. We also show that migrant bird species harbor a greater genetic diversity of parasites compared with nonmigrant species. Taken together, these results suggest that the migratory habits of birds could influence their coevolutionary relationship with their parasites, and that consideration of host traits is important in predicting the outcome of coevolutionary interactions.     

A large‐scale molecular survey of Clinostomum (Digenea,Clinostomidae)

Members of the genus Clinostomum Leidy, 1856 are parasites that mature in birds, with occasional reports in humans. Because morphological characters for reliable discrimination of species are lacking, the number of species considered valid has varied by an order of magnitude. In this study, sequences from the DNA barcode region of cytochrome c oxidase I (CO1) and/or internal transcribed spacer (ITS) from specimens from Mexico, Bolivia, Peru, Brazil, Kenya, China and Thailand were analysed together with published sequences from Europe, Africa, Indonesia and North America. Although ITS and CO1 distances among specimens were strongly correlated, distance‐based analysis of each marker yielded different groups. Putative species indicated by CO1 distances were consistent with available morphological identifications, while those indicated by ITS conflicted with morphological identifications in three cases. There was little overlap in sequence variation within and between species, particularly for CO1. Although ITS and CO1 distances tended to increase in specimens that were further apart geographically, this did not impair distance‐based species delineation. Phylogenetic analysis suggests a deep division between clades of Clinostomum inhabiting the New World and Old World, which parallels the distribution of their principal definitive hosts, the Ardeidae.     

Population structure of three species of Anisakis nematodes recovered from Pacific sardines (Sardinops sagax) distributed throughout the California Current system

Members of the Anisakidae are known to infect over 200 pelagic fish species and have been frequently used as biological tags to identify fish populations. Despite information on the global distribution of Anisakis species, there is little information on the genetic diversity and population structure of this genus, which could be useful in assessing the stock structure of their fish hosts. From 2005 through 2008, 148 larval anisakids were recovered from Pacific sardine (Sardinops sagax) in the California Current upwelling zone and were genetically sequenced. Sardines were captured off Vancouver Island, British Columbia in the north to San Diego, California in the south. Three species, Anisakis pegreffii, Anisakis simplex 'C', and Anisakis simplex s.s., were identified with the use of sequences from the internal transcribed spacers (ITS1 and ITS2) and the 5.8s subunit of the nuclear ribosomal DNA. The degree of nematode population structure was assessed with the use of the cytochrome c oxidase 2 (cox2) mitochondrial DNA gene. All 3 Anisakis species were distributed throughout the study region from 32°N to 50°N latitude. There was no association between sardine length and either nematode infection intensity or Anisakis species recovered. Larval Anisakis species and mitochondrial haplotype distributions from both parsimony networks and analyses of molecular variance revealed a panmictic distribution of these parasites, which infect sardines throughout the California Current ecosystem. Panmictic distribution of the larval Anisakis spp. populations may be a result of the presumed migratory pathways of the intermediate host (the Pacific sardine), moving into the northern portion of the California Current in summer and returning to the southern portion to overwinter and spawn in spring. However, the wider geographic range of paratenic (large piscine predators), and final hosts (cetaceans) can also explain the observed distribution pattern. As a result, the recovery of 3 Anisakis species and a panmictic distribution of their haplotypes could not be used to confirm or deny the presence of population subdivision of Pacific sardines in the California Current system.     

不同地理种群美洲斑潜蝇及近缘种的rDNA-ITS1序列分析和比较

【目的】通过对美洲斑潜蝇Liriomyza sativae Blanchard 不同地理种群及近缘种间的核糖体DNA第一内转录间隔区（rDNA-ITS1）进行比较,分析美洲斑潜蝇不同地理种群间的遗传分化情况,并为美洲斑潜蝇与近缘种间提供分子鉴别标记。【方法】用PCR产物直接测序法及克隆测序法对我国美洲斑潜蝇8个地理种群的rDNA-ITS1序列进行测序,并调用GenBank中3个近缘种的rDNA-ITS序列,运用软件MEGA3.1对美洲斑潜蝇不同地理种群及近缘种间的rDNA-ITS1序列进行分析。【结果】美洲斑潜蝇8个地理种群间的分化程度较低,只有8个变异位点,遗传距离都在0.02以下,但4个近缘种间的碱基差异显著,遗传距离为0.149～0.390,有126个变异位点,12个美洲斑潜蝇特异性识别位点。【结论】虽然基于rDNA-ITS1序列所显示的美洲斑潜蝇各地理种群之间的遗传分化很小,但是其分化趋势与地理分布基本相吻合;得到的12个特异性识别位点不仅可以作为美洲斑潜蝇与其近缘种间鉴别的分子标记,而且可为今后设计鉴别性PCR引物提供重要的参考依据。     

Distinct lineages of Schistocephalus parasites in threespine and ninespine stickleback hosts revealed by DNA sequence analysis

Parasitic interactions are often part of complex networks of interspecific relationships that have evolved in biological communities. Despite many years of work on the evolution of parasitism, the likelihood that sister taxa of parasites can co-evolve with their hosts to specifically infect two related lineages, even when those hosts occur sympatrically, is still unclear. Furthermore, when these specific interactions occur, the molecular and physiological basis of this specificity is still largely unknown. The presence of these specific parasitic relationships can now be tested using molecular markers such as DNA sequence variation. Here we test for specific parasitic relationships in an emerging host-parasite model, the stickleback-Schistocephalus system. Threespine and ninespine stickleback fish are intermediate hosts for Schistocephalus cestode parasites that are phenotypically very similar and have nearly identical life cycles through plankton, stickleback, and avian hosts. We analyzed over 2000 base pairs of COX1 and NADH1 mitochondrial DNA sequences in 48 Schistocephalus individuals collected from threespine and ninespine stickleback hosts from disparate geographic regions distributed across the Northern Hemisphere. Our data strongly support the presence of two distinct clades of Schistocephalus, each of which exclusively infects either threespine or ninespine stickleback. These clades most likely represent different species that diverged soon after the speciation of their stickleback hosts. In addition, genetic structuring exists among Schistocephalus taken from threespine stickleback hosts from Alaska, Oregon and Wales, although it is much less than the divergence between hosts. Our findings emphasize that biological communities may be even more complex than they first appear, and beg the question of what are the ecological, physiological, and genetic factors that maintain the specificity of the Schistocephalus parasites and their stickleback hosts.     

Phylogenetic position of the copepod-infesting parasite Syndinium turbo (Dinoflagellata, Syndinea)

Sequences were determined for the nuclear-encoded small subunit (SSU) rRNA and 5.8S rRNA genes as well as the internal transcribed spacers ITS1 and ITS2 of the parasitic dinoflagellate genus Syndinium from two different marine copepod hosts. Syndinium developed a multicellular plasmodium inside its host and at maturity free-swimming zoospores were released. Syndinium plasmodia in the copepod Paracalanus parvus produced zoospores of three different morphological types. However, full SSU rDNA sequences for the three morphotypes were 100% identical and also their ITS1-ITS2 sequences were identical except for four base pairs. It was concluded that the three morphotypes belong to a single species that was identified as Syndinium turbo, the type species of the dinoflagellate subdivision Syndinea. The SSU rDNA sequence of another Syndinium species infecting Corycaeus sp. was similar to Syndinium turbo except for three base pairs and the ITS1-ITS2 sequences of the two species differed at 34-35 positions. Phylogenetic analyses placed Syndinium as a sister taxon to the blue crab parasite Hematodinium sp. and both parasites were affiliated with the so-called marine alveolate Group II. This corroborates the hypothesis that marine alveolate Group II is Syndinea.     

Molecular characteristics of Camallanus Spp. (Spirurida: Camallanidae) in fishes from China based on its rDNA sequences

In the paper, we explored the intra- and interspecific evolutionary variation among species of Camallanus collected from different fish species in various regions of China. We determined the internal transcribed spacers of ribosomal DNA (ITS rDNA) sequences of these nematodes. The divergence (uncorrected p-distance) of ITS1, ITS2, and ITS rDNA data sets confirmed 2 valid species of Camallanus in China, i.e., C. cotti and C. hypophthalmichthys. The 2 species were distinguished not only by their different morphologies and host ranges but also by a tetranucleotide microsatellite (TTGC)n present in the ITS1 region of C. cotti. Phylogenetic analyses of the nematodes disclosed 2 main clades, corresponding to different individuals of C. cotti and C. hypophthalmichthys from different fish species in various geographical locations, although the interior nodes of each clade received poor support.     

Phylogenetic analysis of nuclear and mitochondrial genes supports species groups for Columbicola (Insecta: Phthiraptera)

The dove louse genus Columbicola has become a model system for studying the interface between microevolutionary processes and macroevolutionary patterns. This genus of parasitic louse (Phthiraptera) contains 80 described species placed into 24 species groups. Samples of Columbicola representing 49 species from 78 species of hosts were obtained and sequenced for mitochondrial (COI and 12S) and nuclear (EF-1alpha) genes. We included multiple representatives from most host species for a total of 154 individual Columbicola, the largest molecular phylogenetic study of a genus of parasitic louse to date. These sequences revealed considerable divergence within several widespread species of lice, and in some cases these species were paraphyletic. These divergences correlated with host association, indicating the potential for cryptic species in several of these widespread louse species. Both parsimony and Bayesian maximum likelihood phylogenetic analyses of these sequences support monophyly for nearly all the non-monotypic species groups included in this study. These trees also revealed considerable structure with respect to biogeographic region and host clade association. These patterns indicated that switching of parasites between host clades is limited by biogeographic proximity.     

Evolution and determinants of host specificity in the genus Lamellodiscus (Monogenea)

The evolution and determinants of host specificity in Lamellodiscus species (Monogenea, Diplectanidae) were investigated. The 20 known Mediterranean species were studied, all parasites of fishes from the family Sparidae (Teleostei). An index of specificity, which takes into account the phylogenetic relationships of their fish host species, was defined. The link between specificity and its potential determinants was investigated in a phylogenetic context using the method of independent contrasts. Host specificity in Lamellodiscus species appeared to be highly constrained by phylogeny, but also linked to host size. Mapping specificity onto the parasite phylogenetic tree suggests that specialist species do not represent an evolutionary dead end, and that specialization is not a derived condition. It is hypothesized that the ability to be generalist or specialist in Lamellodiscus is controlled by intrinsic, phylogenetically-related characteristics, and that specialist species tend to use large hosts, which may be more predictable.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77, 431−443.     

Molecular evidence that Langeronia macrocirra and Langeronia cf. parva (Trematoda: Pleurogenidae) parasites of anurans from Mexico are conspecific

The genus Langeronia parasitizing the intestine of several species of anurans is distributed from North to Central America. We identified Langeronia macrocirra and Langeronia cf. parva from the same host and localities, and present here new data not applicable about their tegumental surface by scanning electron microscopy. We compared sequences of the rDNA ITS2 region and mtDNA cox1 gene for the two morphotypes. ITS2 exhibited a high degree of conservation. Phylogenetic reconstruction using cox1 revealed three clades (I, II, and III), which did not correspond to a previous identification or host. Little divergence was found within clades: sequences were identical in clade I, whereas clade II had 0.27% and clade III had 1.08%. Inter-clade divergence reached 8.69% (I vs. III). This pattern of genetic divergence indicated that both taxa probably belong to the same species, so we posit that the morphological changes could be correlated with development. Increasing sample size and geographical coverage will contribute to the taxonomy of the genus based on morphological and molecular evidence, and will open tracks toward the use of DNA barcodes to the genus in Mexico.     

Molecular phylogeny of species of Ligophorus (Monogenea: Dactylogyridae) and their affinities within the Dactylogyridae

The taxonomic framework of Ligophorus, monogenean specialists of the gills of grey mullets (Mugilidae), is evaluated and its interspecific relationships are assessed for the first time using molecular data. The position of Ligophorus within the paraphyletic Ancyrocephalinae is re-assessed based on newly sequenced species. Furthermore, the relationship between morphometric and genetic interspecific similarities is evaluated. Partial 28S and complete ITS1 rDNA sequences from representatives of 14 of the 16 nominal species of Ligophorus from the Mediterranean, Black and Azov Seas were analysed together with published sequences of members of the Dactylogyridae. The phylogenetic analyses of the Dactylogyridae (i) confirmed the position of Ligophorus within the marine Ancyrocephalinae; (ii) revealed a sister relationship between Ergenstrema and Ligophorus, whose species are all exclusive parasites of grey mullets; and (iii) substantiated the affinities of Ergenstrema with the marine Ancyrocephalinae. The phylogenetic analysis restricted to Ligophorus confirmed the distinct status of the included species. The ITS1 region provided the highest divergence between species and phylograms with the strongest branch support. Both the 28S and ITS1 phylograms revealed two main clades. One included species from hosts with Mediterranean and NE Atlantic distribution and another was formed by species parasitising several Liza spp., including Lz. haematocheilus from the Northwestern Pacific, and Mugil cephalus, which suggests an origin outside the Mediterranean for the latter clade. The phylogenetic evidence presented herein indicated that a combination of host-switching and lineage duplication events accounted for the diversification of this genus in the Mediterranean basin. The agreement between molecular and morphological interspecific similarities observed in Ligophorus supports the validity of morphometric characters used for species identification.     

ITS1 Sequences of Nuclear Ribosomal DNA in Wild Rices and Cultivated Rices of China and Their Phylogenetic Implications

he first internal transcribed spacer (ITS1) of nuclear ribosomal DNA of three wild rice species and two subspecies of cultivated rice, which are distributed in China, was amplified using PCR technique and sequenced with automated fluorescent sequencing. The sequences of ITS1 ranged from 193 bp to 218 bp in size and G/C content varied from 69.3%to 72.7%. In pairwise comparison among the five taxa, sequence site divergence ranged from 1.5 % to 10.6%. Phylogenetic analysis of ITS1 sequences using Wagner parsimony generated a single well-resolved tree, which revealed that Oryza rufipogon was much more closely related to cultivated rice species than to the other two wild species. Oryza granulata was less closely related to either cultivated rice species or the other two wild species, and might be a unique and isolated taxon in the genus Oryza. The phylogenetic relationships of the three wild rice species and two cultivated rice subspecies inferred from ITS1 sequences is highly concordant with those based on the molecular evidence from isozyme, chloroplast DNA (cpDNA), mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) of the genus Oryza.     

Cophylogenetic relationships between Dactylogyrus (Monogenea) ectoparasites and endemic cyprinoids of the north-eastern European peri-Mediterranean region

The study of host–parasite coevolution is one of the cornerstones of evolutionary biology. The majority of fish ectoparasites belonging to the genus Dactylogyrus (Monogenea) exhibit a high degree of host specificity. Therefore, it is expected that their evolutionary history is primarily linked with the evolutionary history of their cyprinoid fish hosts and the historical formation of the landmasses. In the present study, we used a cophylogenetic approach to investigate coevolutionary relationships between endemic Cyprinoidea (Cyprinidae and Leuciscidae) from selected regions in southern Europe and their respective Dactylogyrus species. A total of 49 Dactylogyrus species including endemic and non-endemic species were collected from 62 endemic cyprinoid species in the Balkan and Apennine Peninsulas. However, 21 morphologically identified Dactylogyrus species exhibited different genetic variants (ranging from 2 to 28 variants per species) and some of them were recognized as cryptic species on the basis of phylogenetic reconstruction. Phylogenetic analyses revealed several lineages of endemic and non-endemic Dactylogyrus species reflecting some morphological similarities or host affinities. Using distance-based and event-based cophylogenetic methods, we found a significant coevolutionary signal between the phylogenies of parasites and their hosts. In particular, statistically significant links were revealed between Dactylogyrus species of Barbini (Cyprinidae) and their hosts belonging to the genera Aulopyge, Barbus and Luciobarbus. Additionally, a strong coevolutionary link was found between the generalist parasites D. alatus, D. sphyrna, D. vistulae, and their hosts, and between Dactylogyrus species of Pachychilon (Leuciscidae) and their hosts. Cophylogenetic analyses suggest that host switching played an important role in the evolutionary history of Dactylogyrus parasitizing endemic cyprinoids in southern Europe. We propose that the high diversification of phylogenetically related cyprinoid species in the Mediterranean area is a process facilitating the host switching of specific parasites among highly diverse congeneric cyprinoids.     

虫草属分子系统学研究现状

近年来的分子系统学研究结果表明 ,麦角菌目 (Clavicipitales)与肉座菌目 (Hypocreales)以及虫草属[Cordyceps(Fr.)Link]与麦角菌科 (Clavicipitaceae)内的有关种属关系密切 ,但虫草属为一多系群 ,其中只有新虫草亚属的种类形成单系群。虫草属种类的进化与寄主有一定的关系 ,有关研究显示它们在亲缘关系相差很大的寄主之间多次转移。多个独立的ITS序列研究表明 ,阔孢虫草 (CordycepscrassisporaM .Zangetal.)、甘肃虫草(CordycepsgansuensisK .Y .Zhangetal.)、多轴虫草 (CordycepsmultiaxialisM .Zang&Kinjo)、尼泊尔虫草 (CordycepsnepalensisM .Zang&Kinjo)与冬虫夏草 [Cordycepssinensis(Berk.)Sacc.]为同一物种 ;RAPD和ITS序列分析还显示不同地理分布的冬虫夏草存在明显的遗传分化。分子生物学方法在确定有性型与无性型的关系上已经为多种虫草菌提供了有力的证据。本文主要对虫草属分子系统学研究现状进行了综述 ,同时就分子生物学研究中的取样问题、一些分子方法的适用范围以及有性型与无性型的关系等问题进行了讨论。