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1.
With the decreasing cost and availability of many newly developed bioinformatics pipelines, next-generation sequencing (NGS) has revolutionized plant systematics in recent years. Genome skimming has been widely used to obtain high-copy fractions of the genomes, including plastomes, mitochondrial DNA (mtDNA), and nuclear ribosomal DNA (nrDNA). In this study, through simulations, we evaluated the optimal (minimum) sequencing depth and performance for recovering single-copy nuclear genes (SCNs) from genome skimming data, by subsampling genome resequencing data and generating 10 data sets with different sequencing coverage in silico. We tested the performance of four data sets (plastome, nrDNA, mtDNA, and SCNs) obtained from genome skimming based on phylogenetic analyses of the Vitis clade at the genus level and Vitaceae at the family level, respectively. Our results showed that optimal minimum sequencing depth for high-quality SCNs assembly via genome skimming was about 10× coverage. Without the steps of synthesizing baits and enrichment experiments, coupled with incredibly low sequencing costs, we showcase that deep genome skimming (DGS) is as effective for capturing large data sets of SCNs as the widely used Hyb-Seq approach, in addition to capturing plastomes, mtDNA, and entire nrDNA repeats. DGS may serve as an efficient and economical alternative and may be superior to the popular target enrichment/Hyb-Seq approach.  相似文献   

2.
Blastocystis hominis, a parasite of the human intestine, has recently been positioned within stramenopiles by the small subunit rRNA phylogeny. To further confirm its phylogenetic position using multiple molecular sequence data, we determined the nucleotide sequences putatively encoding small subunit ribosomal RNA, cytosolic-type 70-kDa heat shock protein, translation elongation factor 2, and the non-catalytic 'B' subunit of vacuolar ATPase of B. hominis (HE87-1 strain). Moreover, we determined the translation elongation factor 2 sequence of an apicomplexan parasite, Plasmodium falciparum, that belongs to alveolates. The maximum likelihood analyses of small subunit rRNA and cytosolic-type 70-kDa heat shock protein clearly demonstrated that B. hominis (HE87-1 strain) is positioned within stramenopiles, being congruent with the previous small subunit rRNA analysis, including the sequences of B. hominis (Nand strain) and a Blastocystis isolate from guinea pig. Although no clear resolution among major eukaryotic groups was obtained by the individual phylogenies based on the four molecules analyzed here, a combined analysis of various molecules, including these, clearly indicated that Blastocystis/stramenopiles are the closest relatives of alveolates.  相似文献   

3.
Yunnanopilia longistaminea (W.Z. Li) C.Y. Wu & D.Z. Li, which is a controversial species in Opiliaceae, is treated as a variety of Champereia manillana (Blume) Merrill in the Flora of China and morphological analysis has produced conflicting results regarding its affinity to Melientha and Champereia. To determine the systematic position of Yunnanopilia in Opiliaceae, we selected two nuclear regions (internal transcribed spacer [ITS4‐ITS5] and 18S rDNA) and four chloroplast regions (rbcL, matK, psbAtrnH, and trnStrnG) to test the phylogenetics of the family Opiliaceae using maximum likelihood and Bayesian inference analysis. Morphological characteristics were also examined to clarify the similarities and differences among Y. longistaminea and two closely related species. Agonandra was located at the basal position in the family Opiliaceae; in the large clade including other remaining genera, two main clades were clearly identified and correlated with inflorescence morphological characteristics. All samples of Y. longistaminea formed a clade. Yunnanopilia, Melientha, and Champereia were more closely related than other genera of Opiliaceae. Yunnanopilia longistaminea was sister to M. suavis Pierre and was more closely related to M. suavis than to C. manillana. Morphological analysis also showed that differences in the inflorescences and flowers between Y. longistaminea and M. suavis were substantial enough to warrant the retention of Y. longistaminea in its current genus. Thus, we suggest that the monotypic Yunnanopilia be treated as a distinct genus and that the name Y. longistaminea should be adopted.  相似文献   

4.
The Hawaiian archipelago is often cited as the premier setting to study biological diversification, yet the evolution and phylogeography of much of its biota remain poorly understood. We investigated crab spiders (Thomisidae, Mecaphesa ) that demonstrate contradictory tendencies: (i) dramatic ecological diversity within the Hawaiian Islands, and (ii) accompanying widespread distribution of many species across the archipelago. We used mitochondrial and nuclear genetic data sampled across six islands to generate phylogenetic hypotheses for Mecaphesa species and populations, and included penalized likelihood molecular clock analyses to estimate arrival times on the different islands. We found that 17 of 18 Hawaiian Mecaphesa species were monophyletic and most closely related to thomisids from the Marquesas and Society Islands. Our results indicate that the Hawaiian species evolved from either one or two colonization events to the archipelago. Estimated divergence dates suggested that thomisids may have colonized the Hawaiian Islands as early as ~10 million years ago, but biogeographic analyses implied that the initial diversification of this group was restricted to the younger island of Oahu, followed by back-colonizations to older islands. Within the Hawaiian radiation, our data revealed several well-supported genetically distinct terminal clades corresponding to species previously delimited by morphological taxonomy. Many of these species are codistributed across multiple Hawaiian Islands and some exhibit genetic structure consistent with stepwise colonization of islands following their formation. These results indicate that dispersal has been sufficiently limited to allow extensive ecological diversification, yet frequent enough that interisland migration is more common than speciation.  相似文献   

5.
Summary The evolution of the main regulatory region (D-loop) of the mammalian mitochondrial genome was analyzed by comparing the sequences of eight mammalian species: human, common chimpanzee, pygmy chimpanzee, dolphin, cow, rat, mouse, and rabbit. The best alignment of the sequences was obtained by optimization of the sequence similarities common to all these species.The two peripheral left and right D-loop domains, which contain the main regulatory elements so far discovered, evolved rapidly in a species-specific manner generating heterogeneity in both length and base composition. They are prone to the insertion and deletion of elements and to the generation of short repeats by replication slippage. However, the preservation of some sequence blocks and similar cloverleaf-like structures in these regions, indicates a basic similarity in the regulatory mechanisms of the mitochondrial genome in all mammalian species.We found, particularly in the right domain, significant similarities to the telomeric sequences of the mitochondrial (mt) and nuclear DNA ofTetrahymena thermophila. These sequences may be interpreted as relics of telomeres present in ancestral linear forms of mtDNA or may simply represent efficient templates of RNA primase-like enzymes.Due to their peculiar evolution, the two peripheral domains cannot be used to estimate in a quantitative way the genetic distances between mammalian species. On the other hand the central domain, highly conserved during evolution, behaves as a good molecular clock.Reliable estimates of the times of divergence between closely and distantly related species were obtained from the central domain using a Markov model and assuming nonhomogeneous evolution of nucleotide sites.  相似文献   

6.
Isolated closed basins provide a natural laboratory to study the differentiation among wild populations. Here we examined the phylogenetic relationships of the Southern Altiplano populations of Biomphalaria, a genus with medical importance, using nuclear (ITS1, ITS2) and mitochondrial (16S) ribosomal gene markers and a species of Helisoma as outgroup. Phylogenetic trees based on separate and combined analyses show that these populations form a particular lineage within Biomphalaria along with Biomphalaria peregrina (d'Orbigny, 1835) and Biomphalaria oligoza Paraense, 1974. The origin of this clade was estimated to have occurred in the middle Pleistocene. Molecular analyses showed that the nominal species Biomphalaria crequii ( Courty, 1907 ) from the Salar de Ascotán and Biomphalaria costata (Biese, 1951) from the Salar de Carcote, previously synonymized with Biomphalaria andecola (d'Orbigny, 1835) and B. peregrina, respectively, are distinct taxa. Molecular data did not resolve the relationship of Biomphalaria aymara Valdovinos & Stuardo, 1991 from the Isluga swamps to other Biomphalaria species, but confirm that the populations from the Lauca and Huasco basins may represent a distinct undescribed species of Biomphalaria from the Southern Altiplano. Snails examined for trematodes were found to be positive in some Altiplano localities. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 795–808.  相似文献   

7.
The parsimony and bootstrap branching pattern of major groups of land plants derived from relevant 5S rRNA sequence trees have been discussed in the light of paleobotanical and morphological evidences. Although 5S rRNA sequence information is not useful for dileneating angiosperm relationships, it does capture the earlier phase of land plant evolution. The consensus branching pattern indicates an ancient split of bryophytes and vascular plants from the charophycean algal stem. Among the bryophytes,Marchantia andLophocolea appear to be phylogenetically close and together withPlagiomnium form a monophyletic group.Lycopodium andPsilotum arose early in vascular land plant evolution, independent of fem-sphenopsid branch. Gymnosperms are polyphyletic; conifers, Gnetales and cycads emerge in that order with ginkgo joiningCycas. Among the conifers,Metasequoia,Juniperus andTaxus emerge as a branch independent ofPinus which joins Gnetales. The phylogeny derived from the available ss-RNA sequences shows that angiosperms are monophyletic with monocots and dicots diverging from a common stem. The nucleotide replacements during angiosperm descent from the gymnosperm ancestor which presumably arose around 370 my ago indicates that monocots and dicots diverged around 180 my ago, which is compatible with the reported divergence estimate of around 200 my ago deduced from chloroplast DNA sequences. Since deceased.  相似文献   

8.
Doradidae is a putatively monophyletic group of South American freshwater catfishes containing 30 extant genera and 72 valid species. Only one study to date has attempted to estimate phylogenetic relationships among doradids. This morphological analysis partitioned species into two basal genera ( Wertheimeria and Francisodoras ) and a crown group of three subfamilies (Platydoradinae, Astrodoradinae and Doradinae) whose relationships were unresolved. No subsequent work has been done to resolve the subfamilial trichotomy or to assess whether postulated intergeneric relationships are accurate. We address this problem with complete sequences (2.5 kilobases, kb) of mitochondrial 12S and 16S rRNA genes and partial (1.3 kb) sequences of the nuclear elongation factor-1 alpha (EF1α) gene from representatives of 23 doradid genera (43 species) and 13 outgroups from additional siluriform families. Phylogenetic analysis of these data yields strong support for the monophyly of Doradidae and Astrodoradinae (as well as other relationships), but otherwise shows significant conflict with morphological results. A partial re-examination of published morphological data indicates that many characters may have been incorrectly polarized and many taxa have incorrect state assignments. Our results provide a framework for ongoing efforts to describe the species-level diversity of this poorly understood neotropical family.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 551–575.  相似文献   

9.
The phylogenetic relationship of the genera Arthroderma and Nannizzia, was investigated by mitochondrial DNA analysis based on the restriction-fragment-length polymorphisms. Phylogenetic trees made on ten species. A. benhamiae, A. insingulare, A. quadrifidum, A. simii, A. vanbreuseghemii, N. fulva, N. grubyia, N. gypsea, N. incurvata and N. otae showed no definite distinctions between the genera Arthroderma and Nannizzia. These results support the conclusion of Weitzman et al. that the genera Arthroderma and Nannizzia are congeneric.  相似文献   

10.
The putative complexity of Combretaceae and lack of information on phylogenetic relationships within the family led us to explore relationships between genera of Combretaceae by means of combined analyses of plastid and nuclear sequences. We collected DNA sequence data from the nuclear ribosomal internal transcribed spacer region and plastid rbcL, psaA‐ycf3 spacer and psbA‐trnH spacer for 14 of the 17 genera of Combretaceae. The current classification of the family into two subfamilies, Strephonematoideae and Combretoideae, is corroborated. Within Combretoideae, division into two tribes, Laguncularieae and Combreteae, is strongly supported. Within Combreteae subtribe Terminaliinae, relationships between genera are largely unresolved. Terminalia is not supported as monophyletic and two groups were identified, one containing mainly African species and another of mostly Asian species. Pteleopsis, Buchenavia and Anogeissus are embedded within Terminalia, and we suggest that all genera of Terminaliinae, with the exception of Conocarpus, should be included in an expanded circumscrition of Terminalia. Within subtribe Combretinae, a clade formed by the two monotypic genera Guiera and Calycopteris is sister to the rest of the subtribe. Groupings in Combretinae are consistent with recent results based on morphological data. Combretum is currently divided into three subgenera: Apethalanthum, Cacoucia and Combretum. The last two were included in this study and supported as monophyletic if Quisqualis is included within subgenus Cacoucia. Meiostemon is sister to subgenus Combretum. We recommend that subgenus Combretum should be expanded to include Meiostemon and subgenus Cacoucia to include Quisqualis. The sectional classification within Combretum proposed in earlier morphological studies is confirmed except for the exclusion of C. imberbe from section Hypocrateropsis in a separate and monotypic section and the inclusion of C. zeyheri (section Spathulipetala) in section Macrostigmatea. In order to accommodate C. imberbe, a new section is suggested. The reinstatement of previously recognized sections Grandiflora and Trichopetala, both of which had been sunk into subgenus Cacoucia section Poivrea, is proposed. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 453–476.  相似文献   

11.
Previous molecular phylogenetic analyses of the family Cyperaceae based on rbcL sequences showed Bulbostylis as paraphyletic, with B. atrosanguinea and B. hispidula forming a clade with Nemum spadiceum. On the contrary, phylogenetic analyses of the tribe Abildgaardieae based on nuclear (ITS ribosomal region) and plastid sequences (trnL-F region) showed Bulbostylis as monophyletic, although they only incorporated four species of Bulbostylis and none of Nemum. In this work, we presented a phylogenetic hypothesis of Bulbostylis based on a comprehensive sampling, including species from different continents for the first time. New sequences of Abildgaardia, Crosslandia, Fimbristylis, and Nemum were included to test the monophyly of Bulbostylis. In total, 84 sequences of both ITS and trnL regions were generated. Analyses were performed using Bayesian inference, maximum likelihood, and parsimony. Ancestral state reconstruction was performed using ML, MCMC, and parsimony methods. In all analyses, Bulbostylis resulted paraphyletic as Nemum atracuminatum is nested within it. Most American species of Bulbostylis grouped together, but relationships amongst them appeared poorly resolved. Ancestral state reconstructions of native distribution suggest an African ancestor of Bulbostylis, with at least three introduction independent events of the species in America. Morphological diagnostic characters such as the ‘style base permanence or detachment from the ripe achene’, and the ‘micromorphological patterns of the achene surface’ are homoplastic in this phylogenetic context, and therefore unsuitable to propose infrageneric groupings within the Bulbostylis.  相似文献   

12.
Species delimitation in the Abies chensiensis complex, consisting of A. chensiensis, A. recurvata, A. ernestii and A. ernestii var. salouenensis, has been the subject of a long‐term dispute, as various taxonomic combinations have been proposed. We combined different lines of evidence, including morphological characters and mitochondrial and plastid DNA sequence data, to assess species delimitation. Plastid DNA sequence variation was highly consistent with the morphological result and separated A. recurvata from the other three taxa, but the mitochondrial DNA genealogy was more strongly related to geographical distribution rather than species delimitation, as proposed in previous studies. On the basis of morphological characters and plastid DNA sequence variation, the current species status of A. recurvata was well supported, and we also accepted A. ernestii and A. ernestii var. salouenensis as varieties of A. chensiensis. Furthermore, the phylogeographical history of A. chensiensis was surveyed by molecular data and ecological niche modelling. On the basis of molecular data, the current phylogeographical pattern of the A. chensiensis complex was probably shaped by recent rapid expansions from multiple refugia in the Hengduan Mountains and habitat contraction after the last glaciation. This hypothesis was supported by the results of ecological niche modelling and previous fossil records. Our findings suggest that these fir taxa might have continued to expand their range after the largest glaciation until the end of the last glaciation, but have contracted since then with the increasing temperature and habitat changes. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 175–188.  相似文献   

13.
Summary A maximum likelihood method for inferring evolutionary trees from DNA sequence data was developed by Felsenstein (1981). In evaluating the extent to which the maximum likelihood tree is a significantly better representation of the true tree, it is important to estimate the variance of the difference between log likelihood of different tree topologies. Bootstrap resampling can be used for this purpose (Hasegawa et al. 1988; Hasegawa and Kishino 1989), but it imposes a great computation burden. To overcome this difficulty, we developed a new method for estimating the variance by expressing it explicitly.The method was applied to DNA sequence data from primates in order to evaluate the maximum likelihood branching order among Hominoidea. It was shown that, although the orangutan is convincingly placed as an outgroup of a human and African apes clade, the branching order among human, chimpanzee, and gorilla cannot be determined confidently from the DNA sequence data presently available when the evolutionary rate constancy is not assumed.  相似文献   

14.
15.
Based on molecular data for mitochondrial (Cyt b, COI) and nuclear (IRBP, GHR) genes, and morphological examinations of museum specimens, we examined diversity, species boundaries, and relationships within and between the murine genera Chiromyscus and Niviventer. Phylogenetic patterns recovered demonstrate that Niviventer sensu lato is not monophyletic but instead includes Chiromyscus chiropus, the only previously recognized species of Chiropus. To maintain the genera Niviventer and Chiropus as monophyletic lineages, the scope and definition of the genus Chiromyscus is revised to include at least three distinct species: Chiromyscus chiropus (the type species of Chiromyscus), Chiromyscus langbianis (previously regarded as a species of Niviventer), and a new species, described in this paper under the name Chiromyscus thomasi sp. n.  相似文献   

16.
Two different genomic regions (ND2 mitochondrial gene and EF1-alpha intron) were PCR amplified, cloned and sequenced for the ten known honey bee species collected within their natural range distribution. DNA sequences were analyzed using parsimony, distance and maximum likelihood methods to investigate phylogenetic relationships within Apis. The phylogenetic analyses strongly supported the basic topology recoverable from morphometric analysis, grouping the honey bees into three major clusters: giant bees (A. dorsata, A. binghami, and A. laboriosa), dwarf bees (A. andreniformis and A. florea), and cavity-nesting bees (A. mellifera, A. cerana, A. koschevnikovi, A. nuluensis, and A. nigrocincta). However, the clade of Asian cavity-nesting bees included paraphyletic taxa. Exemplars of Apis cerana collected from divergent portions of its range were less related to each other than were sympatric A. cerana, A. nuluensis, and A. nigrocincta taxa. Nucleotide sequence divergence between allopatrically distributed western (A. mellifera) and eastern (A. cerana, A. koschevnikovi, A. nigrocincta, and A. nuluensis) cavity-nesting species, around 18% for the mitochondrial gene and 10-15% for the nuclear intron, suggested an earlier divergence for these groups than previously estimated from morphometric and behavioral studies. This latter finding neccessitates reevaluation of the hypothesized origin of extant European, African, and west Asian Apis mellifera. Sequence divergence between A. laboriosa and A. dorsata was consistent with behavioral data and supports the species status of A. laboriosa.  相似文献   

17.
Domestic goats (Capra hircus) are spread across the five continents with a census of 1 billion individuals. The worldwide population of goats descends from a limited number of bezoars (Capra aegagrus) domesticated 10 000 YBP (years before the present) in the Fertile Crescent. The extraordinary adaptability and hardiness of goats favoured their rapid spread over the Old World, reaching the Iberian Peninsula and Southern Africa 7000 YBP and 2000 YBP respectively. Molecular studies have revealed one major mitochondrial haplogroup A and five less frequent haplogroups B, C, D, F and G. Moreover, the analysis of autosomal and Y‐chromosome markers has evidenced an appreciable geographic differentiation. The implementation of new molecular technologies, such as whole‐genome sequencing and genome‐wide genotyping, allows for the exploration of caprine diversity at an unprecedented scale, thus providing new insights into the evolutionary history of goats. In spite of a number of pitfalls, the characterization of the functional elements of the goat genome is expected to play a key role in understanding the genetic determination of economically relevant traits. Genomic selection and genome editing also hold great potential, particularly for improving traits that cannot be modified easily by traditional selection.  相似文献   

18.
The genus Tetraophasis is endemic to China and the systematic relationships of the genus in Phasianidae based solely on their morphology are not clear. The phylogenetic position of this genus and other genera in Phasianidae was investigated in this study using the mitochondrial genes cytochrome b (CYT B), NADH dehydrogenase subunit 2 (ND2) and nuclear ovomucoid intron G (OVO-G). Maximum parsimony, Bayesian and maximum likelihood analyses were employed. Comparison between the mitochondrial and nuclear findings suggested that our final combined data had higher resolving power than the separate data. Both separate data and combined data yielded a sister relationship between Tetraophasis and Lophophorus with strong support, which provided new evidence that pheasants and partridges were not monophyletic. In addition, our results indicated a basal position of Ithaginis, but the position of Perdix and Pucrasia were still unresolved. The result of this study provided a phylogenetic background for a revised classification of Galliformes.  相似文献   

19.
Chironius is one of the most speciose genera of the South American colubrid snakes. Although the genus represents a well‐known radiation of diurnal racers, its monophyly, affinities with other Neotropical colubrid genera, and intrageneric relationships are open questions. Here, we present a phylogenetic analysis of Chironius based on a data matrix that combines one nuclear (c‐mos) and two mitochondrial (12S and 16S rRNA) genes with 37 morphological characters derived from scutellation, skull, and hemipenial features. Phylogenetic relationships were inferred using maximum parsimony (MP) and maximum likelihood (ML). Our combined morphological and molecular analyses strongly support the monophyly of the genus Chironius and its sister‐group relationship with a clade formed by the genera Dendrophidion and Drymobius. Phylogenetic relationships within the genus Chironius is still controversial, although five clades are retrieved with medium to strong support. © 2014 The Linnean Society of London  相似文献   

20.
We use fragments of three nuclear genes (Histone 3, 18SrDNA, and 28SrDNA) and three mitochondrial genes (16SrDNA, ND1, and COI) totalling approximately 4.5kb, in addition to morphological data, to estimate the phylogenetic relationships among Anelosimus spiders, well known for their sociality. The analysis includes 67 individuals representing 23 of the 53 currently recognized Anelosimus species and all species groups previously recognized by morphological evidence. We analyse the data using Bayesian, maximum likelihood, and parsimony methods, considering the genes individually as well as combined (mitochondrial, nuclear, and both combined) in addition to a 'total evidence' analysis including morphology. Most of the data partitions are congruent in agreeing on several fundamental aspects of the phylogeny, and the combined molecular data yield a tree broadly similar to an existing morphological hypothesis. We argue that such congruence among data partitions is an important indicator of support that may go undetected by standard robustness estimators. Our results strongly support Anelosimus monophyly, and the monophyly of the recently revised American 'eximius lineage', although slightly altered by excluding A. pacificus. There was consistent support for the scattering of American Anelosimus species in three clades suggesting intercontinental dispersal. Several recently described species are reconstructed as monophyletic, supporting taxonomic decisions based on morphology and behaviour in this taxonomically difficult group. Corroborating previous results from morphology, the molecular data suggest that social species are scattered across the genus and thus that sociality has evolved multiple times, a significant finding for exploring the causes and consequences of social evolution in this group of organisms.  相似文献   

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