共查询到20条相似文献，搜索用时 15 毫秒
1.
Marko Mutanen Mari Kekkonen Sean W. J. Prosser Paul D. N. Hebert Lauri Kaila 《Molecular ecology resources》2015,15(4):967-984
Each holotype specimen provides the only objective link to a particular Linnean binomen. Sequence information from them is increasingly valuable due to the growing usage of DNA barcodes in taxonomy. As type specimens are often old, it may only be possible to recover fragmentary sequence information from them. We tested the efficacy of short sequences from type specimens in the resolution of a challenging taxonomic puzzle: the Elachista dispunctella complex which includes 64 described species with minuscule morphological differences. We applied a multistep procedure to resolve the taxonomy of this species complex. First, we sequenced a large number of newly collected specimens and as many holotypes as possible. Second, we used all >400 bp examine species boundaries. We employed three unsupervised methods (BIN, ABGD, GMYC) with specified criteria on how to handle discordant results and examined diagnostic bases from each delineated putative species (operational taxonomic units, OTUs). Third, we evaluated the morphological characters of each OTU. Finally, we associated short barcodes from types with the delineated OTUs. In this step, we employed various supervised methods, including distance‐based, tree‐based and character‐based. We recovered 658 bp barcode sequences from 194 of 215 fresh specimens and recovered an average of 141 bp from 33 of 42 holotypes. We observed strong congruence among all methods and good correspondence with morphology. We demonstrate potential pitfalls with tree‐, distance‐ and character‐based approaches when associating sequences of varied length. Our results suggest that sequences as short as 56 bp can often provide valuable taxonomic information. The results support significant taxonomic oversplitting of species in the Elachista dispunctella complex. 相似文献
2.
Gergin A. Blagoev Jeremy R. deWaard Sujeevan Ratnasingham Stephanie L. deWaard Liuqiong Lu James Robertson Angela C. Telfer Paul D. N. Hebert 《Molecular ecology resources》2016,16(1):325-341
Approximately 1460 species of spiders have been reported from Canada, 3% of the global fauna. This study provides a DNA barcode reference library for 1018 of these species based upon the analysis of more than 30 000 specimens. The sequence results show a clear barcode gap in most cases with a mean intraspecific divergence of 0.78% vs. a minimum nearest‐neighbour (NN) distance averaging 7.85%. The sequences were assigned to 1359 Barcode index numbers (BINs) with 1344 of these BINs composed of specimens belonging to a single currently recognized species. There was a perfect correspondence between BIN membership and a known species in 795 cases, while another 197 species were assigned to two or more BINs (556 in total). A few other species (26) were involved in BIN merges or in a combination of merges and splits. There was only a weak relationship between the number of specimens analysed for a species and its BIN count. However, three species were clear outliers with their specimens being placed in 11–22 BINs. Although all BIN splits need further study to clarify the taxonomic status of the entities involved, DNA barcodes discriminated 98% of the 1018 species. The present survey conservatively revealed 16 species new to science, 52 species new to Canada and major range extensions for 426 species. However, if most BIN splits detected in this study reflect cryptic taxa, the true species count for Canadian spiders could be 30–50% higher than currently recognized. 相似文献
3.
Christophe Vieira Sofie D'hondt Olivier De Clerck Claude E Payri 《Journal of phycology》2014,50(6):1101-1119
Until the recent use of molecular markers, species diversity of Lobophora, an ecologically important brown algal genus with a worldwide distribution in temperate and tropical seas, has been critically underestimated. Using a DNA‐based taxonomic approach, we re‐examined diversity of the genus from New Caledonia in the Southwest Pacific Ocean. First, species were delineated using general mixed Yule coalescent‐based and barcoding gap approaches applied to a mitochondrial cox3 data set. Results were subsequently confirmed using chloroplast psbA and rbcL data sets. Species delimitation analyses agreed well across markers and delimitation algorithms, with the barcoding gap approach being slightly more conservative. Analyses of the cox3 data set resulted in 31–39 molecular operational taxonomic units (MOTUs), four of which are previously described species (L. asiatica, L. crassa, L. nigrescens s.l., L. pachyventera). Of the remaining MOTUs for which we obtained a representative number of sequences and results are corroborated across analyses and genes, we described 10 species de novo: L. abaculusa, L. abscondita, L. densa, L. dimorpha, L. gibbera, L. hederacea, L. monticola, L. petila, L. rosacea, and L. undulata. Our study presents an excellent case of how a traditional morphology‐based taxonomy fails to provide accurate estimates of algal diversity. Furthermore, the level of Lobophora diversity unveiled from a single locality in the Pacific Ocean raises important questions with respect to the global diversity of the genus, the distributions and range sizes of the individual species, as well as the mechanisms facilitating coexistence. 相似文献
4.
Damon P. Little 《Molecular ecology resources》2014,14(3):437-446
Small portions of the barcode region – mini‐barcodes – may be used in place of full‐length barcodes to overcome DNA degradation for samples with poor DNA preservation. 591,491,286 rbcL mini‐barcode primer combinations were electronically evaluated for PCR universality, and two novel highly universal sets of priming sites were identified. Novel and published rbcL mini‐barcode primers were evaluated for PCR amplification [determined with a validated electronic simulation (n = 2765) and empirically (n = 188)], Sanger sequence quality [determined empirically (n = 188)], and taxonomic discrimination [determined empirically (n = 30 472)]. PCR amplification for all mini‐barcodes, as estimated by validated electronic simulation, was successful for 90.2–99.8% of species. Overall Sanger sequence quality for mini‐barcodes was very low – the best mini‐barcode tested produced sequences of adequate quality (B20 ≥ 0.5) for 74.5% of samples. The majority of mini‐barcodes provide correct identifications of families in excess of 70.1% of the time. Discriminatory power noticeably decreased at lower taxonomic levels. At the species level, the discriminatory power of the best mini‐barcode was less than 38.2%. For samples believed to contain DNA from only one species, an investigator should attempt to sequence, in decreasing order of utility and probability of success, mini‐barcodes F (rbcL1/rbcLB), D (F52/R193) and K (F517/R604). For samples believed to contain DNA from more than one species, an investigator should amplify and sequence mini‐barcode D (F52/R193). 相似文献
5.
The analysis of DNA barcode sequences with varying techniques for cluster recognition provides an efficient approach for recognizing putative species (operational taxonomic units, OTUs). This approach accelerates and improves taxonomic workflows by exposing cryptic species and decreasing the risk of synonymy. This study tested the congruence of OTUs resulting from the application of three analytical methods (ABGD, BIN, GMYC) to sequence data for Australian hypertrophine moths. OTUs supported by all three approaches were viewed as robust, but 20% of the OTUs were only recognized by one or two of the methods. These OTUs were examined for three criteria to clarify their status. Monophyly and diagnostic nucleotides were both uninformative, but information on ranges was useful as sympatric sister OTUs were viewed as distinct, while allopatric OTUs were merged. This approach revealed 124 OTUs of Hypertrophinae, a more than twofold increase from the currently recognized 51 species. Because this analytical protocol is both fast and repeatable, it provides a valuable tool for establishing a basic understanding of species boundaries that can be validated with subsequent studies. 相似文献
6.
O. Hawlitschek J. Morinière G. U. C. Lehmann A. W. Lehmann M. Kropf A. Dunz F. Glaw M. Detcharoen S. Schmidt A. Hausmann N. U. Szucsich S. A. Caetano‐Wyler G. Haszprunar 《Molecular ecology resources》2017,17(5):1037-1053
We present a DNA barcoding study on the insect order Orthoptera that was generated in collaboration between four barcoding projects in three countries, viz. Barcoding Fauna Bavarica (Germany), German Barcode of Life, Austrian Barcode of Life and Swiss Barcode of Life. Our data set includes 748 COI sequences from 127 of the 162 taxa (78.4%) recorded in the three countries involved. Ninety‐three of these 122 species (76.2%, including all Ensifera) can be reliably identified using DNA barcodes. The remaining 26 caeliferan species (families Acrididae and Tetrigidae) form ten clusters that share barcodes among up to five species, in three cases even across different genera, and in six cases even sharing individual barcodes. We discuss incomplete lineage sorting and hybridization as most likely causes of this phenomenon, as the species concerned are phylogenetically young and hybridization has been previously observed. We also highlight the problem of nuclear mitochondrial pseudogenes (numts), a known problem in the barcoding of orthopteran species, and the possibility of Wolbachia infections. Finally, we discuss the possible taxonomic implications of our barcoding results and point out future research directions. 相似文献
7.
Robert W. Bryson Jr 《Molecular ecology resources》2014,14(4):789-793
Bacterial endosymbionts are common among arthropods, and maternally inherited forms can affect the reproductive and behavioural traits of their arthropod hosts. The prevalence of bacterial endosymbionts and their role in scorpion evolution have rarely been investigated. In this study, 61 samples from 40 species of scorpion in the family Vaejovidae were screened for the presence of the bacterial endosymbionts Cardinium, Rickettsia, Spiroplasma and Wolbachia. No samples were infected by these bacteria. However, one primer pair specifically designed to amplify Rickettsia amplified nontarget genes of other taxa. Similar off‐target amplification using another endosymbiont‐specific primer was also found during preliminary screenings. Results caution against the overreliance on previously published screening primers to detect bacterial endosymbionts in host taxa and suggest that primer specificity may be higher in primers targeting nuclear rather than mitochondrial genes. 相似文献
8.
El Mahdi Bendif Ian Probert Margaux Carmichael Sarah Romac Kyoko Hagino Colomban de Vargas 《Journal of phycology》2014,50(1):140-148
Emiliania huxleyi and Gephyrocapsa oceanica are abundant coccolithophore morpho‐species that play key roles in ocean carbon cycling due to their importance as both primary producers and cal‐cifiers. Global change processes such as ocean acidification impact these key calcifying species. The physiology of E. huxleyi, a developing model species, has been widely studied, but its genetic delineation from G. oceanica remains unclear due to a lack of resolution in classical genetic markers. Using nuclear (18S rDNA and 28S rDNA), mitochondrial (cox1, cox2, cox3, rpl16, and dam), and plastidial (16S rDNA, rbcL, tufA, and petA) DNA markers from 99 E. huxleyi and 44 G. oceanica strains, we conducted a multigene/multistrain survey to compare the suitability of different markers for resolving phylogenetic patterns within and between these two morpho‐species. The nuclear genes tested did not provide sufficient resolution to discriminate between the two morpho‐species that diverged only 291Kya. Typical patterns of incomplete lineage sorting were generated in phylogenetic analyses using plastidial genes. In contrast, full morpho‐species delineation was achieved with mitochondrial markers and common intra‐morpho‐species phylogenetic patterns were observed despite differing rates of DNA substitution. Mitochondrial genes are thus promising barcodes for distinguishing these coccolithophore morpho‐species, in particular in the context of environmental monitoring. 相似文献
9.
Jing Li Xin Zheng Yansen Cai Xiuyue Zhang Min Yang Bisong Yue Jing Li 《Molecular ecology resources》2015,15(1):153-167
Identification of rodents is very difficult mainly due to high similarities in morphology and controversial taxonomy. In this study, mitochondrial cytochrome oxidase subunit I (COI) was used as DNA barcode to identify the Murinae and Arvicolinae species distributed in China and to facilitate the systematics studies of Rodentia. In total, 242 sequences (31 species, 11 genera) from Murinae and 130 sequences (23 species, 6 genera) from Arvicolinae were investigated, of which 90 individuals were novel. Genetic distance, threshold method, tree‐based method, online BLAST and BLOG were employed to analyse the data sets. There was no obvious barcode gap. The average K2P distance within species and genera was 2.10% and 12.61% in Murinae, and 2.86% and 11.80% in Arvicolinae, respectively. The optimal threshold was 5.62% for Murinae and 3.34% for Arvicolinae. All phylogenetic trees exhibited similar topology and could distinguish 90.32% of surveyed species in Murinae and 82.60% in Arvicolinae with high support values. BLAST analyses yielded similar results with identification success rates of 92.15% and 93.85% for Murinae and Arvicolinae, respectively. BLOG successfully authenticated 100% of detected species except Leopoldamys edwardsi based on the latest taxonomic revision. Our results support the species status of recently recognized Micromys erythrotis, Eothenomys tarquinius and E. hintoni and confirm the important roles of comprehensive taxonomy and accurate morphological identification in DNA barcoding studies. We believe that, when proper analytic methods are applied or combined, DNA barcoding could serve as an accurate and effective species identification approach for Murinae and Arvicolinae based on a proper taxonomic framework. 相似文献
10.
The monotypic genus Auxenochlorella with its type species A. protothecoides is so far only known from specific habitats such as the sap of several tree species. Several varieties were described according to physiological performances in culture on different organic substrates. However, two strains designated as Auxenochlorella were isolated from other habitats (an endosymbiont of Hydra viridis and an aquatic strain from an acidic volcano stream). We studied those isolates and compared them with six strains of Auxenochlorella belonging to different varieties. The integrative approach used in this study revealed that all strains showed similar morphology but differed in their SSU and ITS rDNA sequences. The Hydra endosymbiont formed a sister taxon to A. protothecoides, which included the varieties protothecoides, galactophila, and communis. The variety acidicola is not closely related to Auxenochlorella and represented its own lineage within the Trebouxiophyceae. In view of these results, we propose a new species of Auxenochlorella, A. symbiontica, for the Hydra symbiont, and a new genus Pumiliosphaera, with its type species, P. acidophila, for acidophilic strain. These results are supported by several compensatory base changes in the conserved region of ITS‐2 and ITS‐2 DNA barcodes. 相似文献
11.
Kjersti S. Kvie Silje Hogner Leif Aarvik Jan T. Lifjeld Arild Johnsen 《Ecology and evolution》2013,3(1):126-144
Deep sympatric intraspecific divergence in mtDNA may reflect cryptic species or formerly distinct lineages in the process of remerging. Preliminary results from DNA barcoding of Scandinavian butterflies and moths showed high intraspecific sequence variation in the autumnal moth, Epirrita autumnata. In this study, specimens from different localities in Norway and some samples from Finland and Scotland, with two congeneric species as outgroups, were sequenced with mitochondrial and nuclear markers to resolve the discrepancy found between mtDNA divergence and present species‐level taxonomy. We found five COI sub‐clades within the E. autumnata complex, most of which were sympatric and with little geographic structure. Nuclear markers (ITS2 and Wingless) showed little variation and gave no indications that E. autumnata comprises more than one species. The samples were screened with primers for Wolbachia outer surface gene (wsp) and 12% of the samples tested positive. Two Wolbachia strains were associated with different mtDNA sub‐clades within E. autumnata, which may indicate indirect selection/selective sweeps on haplotypes. Our results demonstrate that deep mtDNA divergences are not synonymous with cryptic speciation and this has important implications for the use of mtDNA in species delimitation, like in DNA barcoding. 相似文献
12.
Lauren Speare Sarah W. Davies John P. Balmonte Justin Baumann Karl D. Castillo 《Molecular ecology》2020,29(13):2334-2348
A coral's capacity to alter its microbial symbionts may enhance its fitness in the face of climate change. Recent work predicts exposure to high environmental variability may increase coral resilience and adaptability to future climate conditions. However, how this heightened environmental variability impacts coral‐associated microbial communities remains largely unexplored. Here, we examined the bacterial and algal symbionts associated with two coral species of the genus Siderastrea with distinct life history strategies from three reef sites on the Belize Mesoamerican Barrier Reef System with low or high environmental variability. Our results reveal bacterial community structure, as well as alpha‐ and beta‐diversity patterns, vary by host species. Differences in bacterial communities between host species were partially explained by high abundance of Deltaproteobacteria and Rhodospirillales and high bacterial diversity in Siderastrea radians. Our findings also suggest Siderastrea spp. have dynamic core bacterial communities that likely drive differences observed in the entire bacterial community, which may play a critical role in rapid acclimatization to environmental change. Unlike the bacterial community, Symbiodiniaceae composition was only distinct between host species at high thermal variability sites, suggesting that different factors shape bacterial versus algal communities within the coral holobiont. Our findings shed light on how domain‐specific shifts in dynamic microbiomes may allow for unique methods of enhanced host fitness. 相似文献
13.
Muhammad Ashfaq Muhammad Asif Zahid Iqbal Anjum Yusuf Zafar 《Molecular ecology resources》2013,13(4):573-582
Although two plastid regions have been adopted as the standard markers for plant DNA barcoding, their limited resolution has provoked the consideration of other gene regions, especially in taxonomically diverse genera. The genus Gossypium (cotton) includes eight diploid genome groups (A–G, and K) and five allotetraploid species which are difficult to discriminate morphologically. In this study, we tested the effectiveness of three widely used markers (matK, rbcL, and ITS2) in the discrimination of 20 diploid and five tetraploid species of cotton. Sequences were analysed locus‐wise and in combinations to determine the most effective strategy for species identification. Sequence recovery was high, ranging from 92% to 100% with mean pairwise interspecific distance highest for ITS2 (3.68%) and lowest for rbcL (0.43%). At a 0.5% threshold, the combination of matK+ITS2 produced the greatest number of species clusters. Based on ‘best match’ analysis, the combination of matK+ITS2 was best, while based on ‘all species barcodes’ analysis, ITS2 gave the highest percentage of correct species identifications (98.93%). The combination of sequences for all three markers produced the best resolved tree. The disparity index test based on matK+rbcL+ITS2 was significant (P < 0.05) for a higher number of species pairs than the individual gene sequences. Although all three barcodes separated the species with respect to their genome type, no single combination of barcodes could differentiate all the Gossypium species, and tetraploid species were particularly difficult. 相似文献
14.
DNA barcoding methods use a single locus (usually the mitochondrial COI gene) to assign unidentified specimens to known species in a library based on a genetic distance threshold that distinguishes between‐species divergence from within‐species diversity. Recently developed species delimitation methods based on the multispecies coalescent (MSC) model offer an alternative approach to individual assignment using either single‐locus or multiloci sequence data. Here, we use simulations to demonstrate three features of an MSC method implemented in the program bpp . First, we show that with one locus, MSC can accurately assign individuals to species without the need for arbitrarily determined distance thresholds (as required for barcoding methods). We provide an example in which no single threshold or barcoding gap exists that can be used to assign all specimens without incurring high error rates. Second, we show that bpp can identify cryptic species that may be misidentified as a single species within the library, potentially improving the accuracy of barcoding libraries. Third, we show that taxon rarity does not present any particular problems for species assignments using bpp and that accurate assignments can be achieved even when only one or a few loci are available. Thus, concerns that have been raised that MSC methods may have problems analysing rare taxa (singletons) are unfounded. Currently, barcoding methods enjoy a huge computational advantage over MSC methods and may be the only approach feasible for massively large data sets, but MSC methods may offer a more stringent test for species that are tentatively assigned by barcoding. 相似文献
15.
Chia‐Hao Chang Kwang‐Tsao Shao Han‐Yang Lin Yung‐Chieh Chiu Mao‐Ying Lee Shih‐Hui Liu Pai‐Lei Lin 《Molecular ecology resources》2017,17(4):796-805
Species identification based on the DNA sequence of a fragment of the cytochrome c oxidase subunit I gene in the mitochondrial genome, DNA barcoding, is widely applied to assist in sustainable exploitation of fish resources and the protection of fish biodiversity. The aim of this study was to establish a reliable barcoding reference database of the native ray‐finned fishes in Taiwan. A total of 2993 individuals, belonging to 1245 species within 637 genera, 184 families and 29 orders of ray‐finned fishes and representing approximately 40% of the recorded ray‐finned fishes in Taiwan, were PCR amplified at the barcode region and bidirectionally sequenced. The mean length of the 2993 barcodes is 549 bp. Mean congeneric K2P distance (15.24%) is approximately 10‐fold higher than the mean conspecific one (1.51%), but approximately 1.4‐fold less than the mean genetic distance between families (20.80%). The Barcode Index Number (BIN) discordance report shows that 2993 specimens represent 1275 BINs and, among them, 86 BINs are singletons, 570 BINs are taxonomically concordant, and the other 619 BINs are taxonomically discordant. Barcode gap analysis also revealed that more than 90% of the collected fishes in this study can be discriminated by DNA barcoding. Overall, the barcoding reference database established by this study reveals the need for taxonomic revisions and voucher specimen rechecks, in addition to assisting in the management of Taiwan's fish resources and diversity. 相似文献
16.
17.
Cesc Múrria Amanda T. Rugenski Matt R. Whiles Alfried P. Vogler 《Diversity & distributions》2015,21(8):938-949
18.
Per Milberg Karl‐Olof Bergman Kerem Sancak Nicklas Jansson 《Ecology and evolution》2016,6(6):1614-1625
Old living oaks (Quercus robur) are known as a very species‐rich habitat for saproxylic beetles, but it is less clear to what extent such veteran trees differ from an even rarer feature: downed trunks of large oaks. In this study, we set out to sample this habitat, using window traps, with two aims: (1) to describe the variation of assemblages among downed trunks of different type and (2) to compare beetles on downed oaks with data from veteran standing trees. The results showed that trunk volume and sun exposure better explained assemblages as well as species numbers on downed trunks than did decay stage. Furthermore, species classified as facultative saproxylic species showed weak or no differentiation among downed trunks. Species with different feeding habits showed no apparent differentiation among downed trunks. Furthermore, species composition on dead, downed oak trunks differed sharply from that of living, veteran oaks. Wood or bark feeders were more common on veterans than downed trunks, but there was no difference for those species feeding on fungi or those feeding on insects and their remains. In conclusion, for a successful conservation of the saproxylic beetle fauna it is important to keep downed oak trunks, and particularly large ones, in forest and pastures as they constitute a saproxylic habitat that differs from that of living trees. 相似文献
19.
Thomas Knebelsberger Monica Landi Hermann Neumann Matthias Kloppmann Anne F. Sell Patrick D. Campbell Silke Laakmann Michael J. Raupach Gary R. Carvalho Filipe O. Costa 《Molecular ecology resources》2014,14(5):1060-1071
Valid fish species identification is an essential step both for fundamental science and fisheries management. The traditional identification is mainly based on external morphological diagnostic characters, leading to inconsistent results in many cases. Here, we provide a sequence reference library based on mitochondrial cytochrome c oxidase subunit I (COI) for a valid identification of 93 North Atlantic fish species originating from the North Sea and adjacent waters, including many commercially exploited species. Neighbour‐joining analysis based on K2P genetic distances formed nonoverlapping clusters for all species with a ≥99% bootstrap support each. Identification was successful for 100% of the species as the minimum genetic distance to the nearest neighbour always exceeded the maximum intraspecific distance. A barcoding gap was apparent for the whole data set. Within‐species distances ranged from 0 to 2.35%, while interspecific distances varied between 3.15 and 28.09%. Distances between congeners were on average 51‐fold higher than those within species. The validation of the sequence library by applying BOLDs barcode index number (BIN) analysis tool and a ranking system demonstrated high taxonomic reliability of the DNA barcodes for 85% of the investigated fish species. Thus, the sequence library presented here can be confidently used as a benchmark for identification of at least two‐thirds of the typical fish species recorded for the North Sea. 相似文献
20.
Feng‐Ming Ren Ying‐Wei Wang Zhi‐Chao Xu Ying Li Tian‐Yi Xin Jian‐Guo Zhou Yao‐Dong Qi Xue‐Ping Wei Hui Yao Jing‐Yuan Song 《Ecology and evolution》2019,9(4):1934-1945
The genus Corydalis is recognized as one of the most taxonomically challenging plant taxa. It is mainly distributed in the Himalaya–Hengduan Mountains, a global biodiversity hotspot. To date, no effective solution for species discrimination and taxonomic assignment in Corydalis has been developed. In this study, five nuclear and chloroplast DNA regions, ITS, ITS2, matK, rbcL, and psbA‐trnH, were preliminarily assessed based on their ability to discriminate Corydalis to eliminate inefficient regions, and the three regions showing good performance (ITS, ITS2 and matK) were then evaluated in 131 samples representing 28 species of 11 sections of four subgenera in Corydalis using three analytical methods (NJ, ML, MP tree; K2P‐distance and BLAST). The results showed that the various approaches exhibit different species identification power and that BLAST shows the best performance among the tested approaches. A comparison of different barcodes indicated that among the single barcodes, ITS (65.2%) exhibited the highest identification success rate and that the combination of ITS + matK (69.6%) provided the highest species resolution among all single barcodes and their combinations. Three Pharmacopoeia‐recorded medicinal plants and their materia medica were identified successfully based on the ITS and ITS2 regions. In the phylogenetic analysis, the sections Thalictrifoliae, Sophorocapnos, Racemosae, Aulacostigma, and Corydalis formed well‐supported separate lineages. We thus hypothesize that the five sections should be classified as an independent subgenus and that the genus should be divided into three subgenera. In this study, DNA barcoding provided relatively high species discrimination power, indicating that it can be used for species discrimination in this taxonomically complicated genus and as a potential tool for the authentication of materia medica belonging to Corydalis. 相似文献