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1.
Although resolving phylogenetic relationships and establishing species limits are primary goals of systematics, these tasks remain challenging at both conceptual and analytical levels. Here, we integrated genomic and phenotypic data and employed a comprehensive suite of coalescent‐based analyses to develop and evaluate competing phylogenetic and species delimitation hypotheses in a recent evolutionary radiation of grasshoppers (Chorthippus binotatus group) composed of two species and eight putative subspecies. To resolve the evolutionary relationships within this complex, we first evaluated alternative phylogenetic hypotheses arising from multiple schemes of genomic data processing and contrasted genetic‐based inferences with different sources of phenotypic information. Second, we examined the importance of number of loci, demographic priors, number and kind of phenotypic characters and sex‐based trait variation for developing alternative species delimitation hypotheses. The best‐supported topology was largely compatible with phenotypic data and showed the presence of two clades corresponding to the nominative species groups, one including three well‐resolved lineages and the other comprising a four‐lineage polytomy and a well‐differentiated sister taxon. Integrative species delimitation analyses indicated that the number of employed loci had little impact on the obtained inferences but revealed the higher power provided by an increasing number of phenotypic characters and the usefulness of assessing their phylogenetic information content and differences between sexes in among‐taxa trait variation. Overall, our study highlights the importance of integrating multiple sources of information to test competing phylogenetic hypotheses and elucidate the evolutionary history of species complexes representing early stages of divergence where conflicting inferences are more prone to appear. 相似文献
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Nemanja Gojkovi&#x; Ljubinka Francuski Jasmina Ludo&#x;ki Vesna Milankov 《Ecology and evolution》2020,10(17):9428-9443
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Population structure of pests is an important issue when designing management strategies to optimize control measures. In this study, we investigated a spatial pattern of genetic and phenotypic variation within seven urban and within six rural populations of Culex pipiens from Vojvodina Province (Serbia) incorporating landscape genetic methods (using allozyme data) and wing size and shape (using geometric morphometric approach). Comparing rural samples, no strong genetic groupings of individuals were detected. Nevertheless, traditional approaches where individuals are pre‐assigned to populations, including F statistics and amova (analysis of molecular variance), revealed low, but significant genetic differentiation among samples. Similarly, phenotypic data (wing size and shape) indicated some level of heterogeneity among rural samples. Contrary to genetic homogeneity found within rural biotype, the individual‐based structuring characterized urban biotype. Geneland revealed the presence of two genetic clusters within urban group which is in concordance with FST and amova results. These results showed that sample from Novi Sad (NS) is a distinct genetic unit, which has been likely resulted in intensive insecticide use over several decades. Furthermore, phenotypic differentiation supported the existence of spatial structuring. Therefore, complementary use of molecular markers and phenotypic traits may be a powerful tool for revealing hidden spatial diversity within Cx. pipiens. 相似文献
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CLARE L. O'REILLY fls ROBYN S. COWAN JULIE A. HAWKINS 《Botanical journal of the Linnean Society. Linnean Society of London》2007,155(4):467-476
Amplified fragment length polymorphism (AFLP) genetic fingerprinting of 14 accessions of Chara curta and Chara aspera Willd., sampled across a range of habitats and morphologies in Britain, suggests that these taxa are part of the variation within a single species complex. Two primer combinations generating 397 fragments (97% of which were polymorphic), analysed by Jaccard's similarity coefficient and principal co-ordinate analysis, did not recover groups which reflect the current taxonomy. By contrast with the genetic study, a Gower general similarity coefficient and principal co-ordinate analysis of 52 morphological characters recovered the currently recognized species groups. A Mantel test showed no significant correlation between the genetic data and the morphological data, supporting the hypothesis that phenotypic variability in Chara L. is either to some extent environmentally induced or represents developmental stages. Implications for the conservation status of C. curta in Britain are discussed. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 467–476. 相似文献
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Paolo Franchini Carmelo Fruciano Maria L. Spreitzer Julia C. Jones Kathryn R. Elmer Frederico Henning Axel Meyer 《Molecular ecology》2014,23(7):1828-1845
Determining the genetic bases of adaptations and their roles in speciation is a prominent issue in evolutionary biology. Cichlid fish species flocks are a prime example of recent rapid radiations, often associated with adaptive phenotypic divergence from a common ancestor within a short period of time. In several radiations of freshwater fishes, divergence in ecomorphological traits — including body shape, colour, lips and jaws — is thought to underlie their ecological differentiation, specialization and, ultimately, speciation. The Midas cichlid species complex (Amphilophus spp.) of Nicaragua provides one of the few known examples of sympatric speciation where species have rapidly evolved different but parallel morphologies in young crater lakes. This study identified significant QTL for body shape using SNPs generated via ddRAD sequencing and geometric morphometric analyses of a cross between two ecologically and morphologically divergent, sympatric cichlid species endemic to crater Lake Apoyo: an elongated limnetic species (Amphilophus zaliosus) and a high‐bodied benthic species (Amphilophus astorquii). A total of 453 genome‐wide informative SNPs were identified in 240 F2 hybrids. These markers were used to construct a genetic map in which 25 linkage groups were resolved. Seventy‐two segregating SNPs were linked to 11 QTL. By annotating the two most highly supported QTL‐linked genomic regions, genes that might contribute to divergence in body shape along the benthic–limnetic axis in Midas cichlid sympatric adaptive radiations were identified. These results suggest that few genomic regions of large effect contribute to early stage divergence in Midas cichlids. 相似文献
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Vicente Hernández-Ortiz Nelson A. Canal Juan O. Tigrero Salas Freddy M. Ruíz-Hurtado José F. Dzul-Cauich 《ZooKeys》2015,(540):95-124
Previous morphometric studies based on linear measurements of female structures of the aculeus, mesonotum, and wing revealed the existence of seven morphotypes within the Anastrepha
fraterculus cryptic species complex along the Neotropical Region. The current research followed linear and geometric morphometric approaches in 40 population samples of the nominal species Anastrepha
fraterculus (Wiedemann) spread throughout the Meso-American and Pacific Neotropical dominions (including Mexico, Central America, Venezuela, Colombia, Ecuador, and Peru). The goals were to explore the phenotypic relationships of the morphotypes in these biogeographical areas; evaluate the reliability of procedures used for delimitation of morphotypes; and describe their current distribution. Findings determined that morphotypes previously recognized via the linear morphometrics were also supported by geometric morphometrics of the wing shape. In addition, we found an eighth morphotype inhabiting the highlands of Ecuador and Peru. Morphotypes are related into three natural phenotypic groups nominated as Mesoamerican-Caribbean lineage, Andean lineage, and Brazilian lineage. The hypothesis that lineages are not directly related to each other is discussed, supported by their large morphological divergence and endemicity in these three well-defined biogeographic areas. In addition, this hypothesis of the non-monophyly of the Anastrepha
fraterculus complex is also supported by evidence from other authors based on molecular studies and the strong reproductive isolation between morphs from different lineages. 相似文献
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Lacie G. Newton James Starrett Brent E. Hendrixson Shahan Derkarabetian Jason E. Bond 《Molecular ecology》2020,29(12):2269-2287
Although species delimitation can be highly contentious, the development of reliable methods to accurately ascertain species boundaries is an imperative step in cataloguing and describing Earth's quickly disappearing biodiversity. Spider species delimitation remains largely based on morphological characters; however, many mygalomorph spider populations are morphologically indistinguishable from each other yet have considerable molecular divergence. The focus of our study, the Antrodiaetus unicolor species complex containing two sympatric species, exhibits this pattern of relative morphological stasis with considerable genetic divergence across its distribution. A past study using two molecular markers, COI and 28S, revealed that A. unicolor is paraphyletic with respect to A. microunicolor. To better investigate species boundaries in the complex, we implement the cohesion species concept and use multiple lines of evidence for testing genetic exchangeability and ecological interchangeability. Our integrative approach includes extensively sampling homologous loci across the genome using a RADseq approach (3RAD), assessing population structure across their geographic range using multiple genetic clustering analyses that include structure , principal components analysis and a recently developed unsupervised machine learning approach (Variational Autoencoder). We evaluate ecological similarity by using large‐scale ecological data for niche‐based distribution modelling. Based on our analyses, we conclude that this complex has at least one additional species as well as confirm species delimitations based on previous less comprehensive approaches. Our study demonstrates the efficacy of genomic‐scale data for recognizing cryptic species, suggesting that species delimitation with one data type, whether one mitochondrial gene or morphology, may underestimate true species diversity in morphologically homogenous taxa with low vagility. 相似文献
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Gregor A. Wachter Christoph Muster Wolfgang Arthofer Günther Raspotnig Petra Föttinger Christian Komposch Birgit C. Schlick‐Steiner 《Molecular ecology》2015,24(4):863-889
Species delimitation is fundamental for biological studies, yet precise delimitation is not an easy task, and every involved approach has an inherent failure rate. Integrative taxonomy, a method that merges multiple lines of evidence, can profoundly contribute to reliable alpha‐taxonomy and shed light on the processes behind speciation. In this study, we explored and validated species limits in a group of closely related Megabunus harvestmen (Eupnoi, Phalangiidae) endemic to the European Alps. Without a priori species hypotheses, we used multiple sources of inference, including mitochondrial and multilocus nuclear DNA, morphometrics and chemistry. The results of these discovery approaches revealed morphological crypsis and multiple new species within two of the five hitherto known species. Based on our analyses, we discussed the most plausible evolutionary scenarios, invoked the most reasonable species hypotheses and validated the new species limits. Building upon the achieved rigour, three new species, Megabunus cryptobergomas Muster and Wachter sp. nov., Megabunus coelodonta Muster and Steiner sp. nov., and Megabunus lentipes Muster and Komposch sp. nov., are formally described. In addition, we provide a dichotomous morphological key to the Megabunus species of the Alps. Our work demonstrates the suitability of integrative, discovery‐based approaches in combination with validation approaches to precisely characterize species and enabled us to implement nomenclatural consequences for this genus. 相似文献
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Manja Hethke Kai Hartmann Matthias Alberti Theresa Kutzner Martin Schwentner 《Palaeontology》2023,66(1):e12634
Fossil spinicaudatan taxonomy heavily relies on carapace features (size, shape, ornamentation) and palaeontologists have greatly refined methods to study and describe carapace variability. Whether carapace features alone are sufficient for distinguishing between species of a single genus has remained untested. In our study, we tested common palaeontological methods on 481 individuals of the extant Australian genus Ozestheria that have been previously assigned to ten species based on genetic analysis. All species are morphologically distinct based on geometric morphometrics (p ≤ 0.001), but they occupy overlapping regions in Ozestheria morphospace. Linear discriminant analysis of Fourier shape coefficients reaches a mean model performance of 93.8% correctly classified individuals over all possible 45 pairwise species comparisons. This can be further increased by combining the size and shape datasets. Nine of the ten examined species are clearly sexually dimorphic but male and female morphologies strongly overlap within species with little influence on model performance. Ornamentation is commonly species-diagnostic; seven ornamentation types are distinguished of which six are species-specific while one is shared by four species. A transformation of main ornamental features (e.g. from punctate to smooth) can occur among closely related species suggesting short evolutionary timescales. Our overall results support the taxonomic value of carapace features, which should also receive greater attention in the taxonomy of extant species. The extensive variation in carapace shape and ornamentation is noteworthy and several species would probably have been assigned to different genera or families if these had been fossils, bearing implications for the systematics of fossil Spinicaudata. 相似文献
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Species are considered to be the basic unit of ecological and evolutionary studies. As multilocus genomic data are increasingly available, there have been considerable interests in the use of DNA sequence data to delimit species. In this study, we show that machine learning can be used for species delimitation. Our method treats the species delimitation problem as a classification problem for identifying the category of a new observation on the basis of training data. Extensive simulation is first conducted over a broad range of evolutionary parameters for training purposes. Each pair of known populations is combined to form training samples with a label of “same species” or “different species”. We use support vector machine (SVM) to train a classifier using a set of summary statistics computed from training samples as features. The trained classifier can classify a test sample to two outcomes: “same species” or “different species”. Given multilocus genomic data of multiple related organisms or populations, our method (called CLADES) performs species delimitation by first classifying pairs of populations. CLADES then delimits species by maximizing the likelihood of species assignment for multiple populations. CLADES is evaluated through extensive simulation and also tested on real genetic data. We show that CLADES is both accurate and efficient for species delimitation when compared with existing methods. CLADES can be useful especially when existing methods have difficulty in delimitation, for example with short species divergence time and gene flow. 相似文献
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已有的各个物种概念对物种的认识类似盲人摸象, 只包含了物种的某一个方面; 而一个分化后期的成熟物种应涵盖了所有的物种概念。但是, 尚未到达分化后期的物种往往又已开始新一轮的物种分化; 自然中存在的多数“物种”处于分化路上。这种循环往复连续分化产生的物种, 存在种间生殖隔离不彻底、基因流频繁发生、网状进化突出等现象。此外, 对于不同的物种对, 最早开始分化的基因以及不同物种概念所要求的条件的分化顺序不是统一的, 而是随机的。定义一个适合所有“分化路上的物种”概念存在较大困难。但是, 应采用尽可能多的物种概念来界定分化路上的物种、发表新种和进行分类处理; 也应承认种间可能广泛存在不完全的生殖隔离和有限的基因流, 即有不属于两个物种群体的杂交或回交个体的存在。这样划分的物种比只依据一个物种概念认定的物种具有更高的客观性和科学性。 相似文献
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Mark A. Phuong Marisa C. W. Lim Daniel R. Wait Kevin C. Rowe Craig Moritz 《Biological journal of the Linnean Society. Linnean Society of London》2014,113(4):1136-1151
We apply an integrative taxonomy approach to delimit species of ground squirrels in the genus Otospermophilus because the diverse evolutionary histories of organisms shape the existence of taxonomic characters. Previous studies of mitochondrial DNA from this group recovered three divergent lineages within Otospermophilus beecheyi separated into northern, central, and southern geographical populations, with Otospermophilus atricapillus nested within the southern lineage of O. beecheyi. To further evaluate species boundaries within this complex, we collected additional genetic data (one mitochondrial locus, 11 microsatellite markers, and 11 nuclear loci), environmental data (eight bioclimatic variables), and morphological data (23 skull measurements). We used the maximum number of possible taxa (O. atricapillus, Northern O. beecheyi, Central O. beecheyi, and Southern O. beecheyi) as our operational taxonomic units (OTUs) and examined patterns of divergence between these OTUs. Phenotypic measures (both environmental and morphological) showed little differentiation among OTUs. By contrast, all genetic datasets supported the evolutionary independence of Northern O. beecheyi, although they were less consistent in their support for other OTUs as distinct species. Based on these data, we support the conclusions from a previous study that synonymized O. atricapillus with O. beecheyi, and we elevate the northern lineage of O. beecheyi to a separate species. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 1136–1151. 相似文献
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Aurlien Miralles Jacques Ducasse Sophie Brouillet Tomas Flouri Tomochika Fujisawa Paschalia Kapli L. Lacey Knowles Sangeeta Kumari Alexandros Stamatakis Jeet Sukumaran Sarah Lutteropp Miguel Vences Nicolas Puillandre 《Molecular ecology resources》2022,22(1):430-438
A wide range of data types can be used to delimit species and various computer-based tools dedicated to this task are now available. Although these formalized approaches have significantly contributed to increase the objectivity of species delimitation (SD) under different assumptions, they are not routinely used by alpha-taxonomists. One obvious shortcoming is the lack of interoperability among the various independently developed SD programs. Given the frequent incongruences between species partitions inferred by different SD approaches, researchers applying these methods often seek to compare these alternative species partitions to evaluate the robustness of the species boundaries. This procedure is excessively time consuming at present, and the lack of a standard format for species partitions is a major obstacle. Here, we propose a standardized format, SPART, to enable compatibility between different SD tools exporting or importing partitions. This format reports the partitions and describes, for each of them, the assignment of individuals to the “inferred species”. The syntax also allows support values to be optionally reported, as well as original trees and the full command lines used in the respective SD analyses. Two variants of this format are proposed, overall using the same terminology but presenting the data either optimized for human readability (matricial SPART) or in a format in which each partition forms a separate block (SPART.XML). ABGD, DELINEATE, GMYC, PTP and TR2 have already been adapted to output SPART files and a new version of LIMES has been developed to import, export, merge and split them. 相似文献
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Siti Zafirah Ghazali;Sébastien Lavoué;Norli Fauzani Mohd Abu Hassan Alshari;Danial Hariz Zainal Abidin;Jamsari Amirul Firdaus Jamaluddin;Min Pau Tan;Siti Azizah Mohd Nor; 《Zoologica scripta》2024,53(2):157-174
Glass-perchlets of the genus Ambassis (Teleostei; Ambassidae) form an important component of the brackish and marine coastal fish communities of tropical Asia. However, their species-level diversity is still poorly documented because of the absence of recent taxonomic revisions in this region and the limited availability of specimens for research. In addition, long-standing taxonomic and nomenclatural issues complicate the studies of this genus. Herein, we examine the diversity of Ambassis in Peninsular Malaysia using an integrative taxonomic approach and a large set of recently collected specimens from this region. Our initial morphological observations of 260 specimens revealed the presence of eight species, identified as Ambassis dussumieri, Ambassis interrupta, Ambassis kopsii, Ambassis macracanthus, Ambassis nalua, Ambassis octava, Ambassis urotaenia and Ambassis vachellii. We then sequenced the barcode fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene for 122 of our specimens, representing all eight morpho-species. Automatic species delimitation methods recovered nine Molecular Operational Taxonomic Units (MOTUs) because A. interrupta is made of two MOTUs. Morphological re-examination within A. interrupta detected variation at one character, congruent with molecular delimitation. Overall, our integrative approach unveiled rich species-level diversity within the genus Ambassis in Peninsular Malaysia, with the presence of nine species. Further comparisons between our COI dataset and the COI sequences archived in the Barcode of Life Data System (BOLD) from specimens of Ambassis broadly collected in tropical Asian regions, indicated regional-scale hidden diversity and identification conflicts, triggering the need for a complete taxonomic revision of this genus. 相似文献
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TONYA MOUSSEAU DEREK S. SIKES 《Biological journal of the Linnean Society. Linnean Society of London》2011,102(2):311-333
Allopatric populations that show genetic differentiation but lack phenotypic diagnosability are difficult to classify. In 1946, Arnett described a new species of burying beetle (Silphidae: Nicrophorus) from Luzon Island, Philippines, Nicrophorus benguetensis. In 2002, Sikes et al., finding the species to be inconsistently diagnosable, synonymized N. benguetensis under Nicrophorus nepalensis Hope 1831. We rigorously and quantitatively test the validity of N. benguetensis using several different species delimitation criteria. We employed discrete and quantitative character‐based methods to test similarity criteria using linear morphometrics in a discriminant analysis framework, and percentage sequence divergences based on sequences from four mitochondrial DNA (mtDNA) genes (COI, COII, ND4 and ND5) and two nuclear genes [28S (D2 region) and CAD]. We also employed tree‐based methods to test phylogenetic criteria using mtDNA sequences and morphology with parsimony, Bayesian inference and maximum likelihood. The analysis of discrete phenotypic characters did not reliably diagnose N. benguetensis. The results of the discriminant analysis provided moderate support for the validity of N. benguetensis (71.4% of the specimens were properly classified). There is adequate genetic distance between N. benguetensis and its nearest neighbour for DNA barcoding to identify an unknown sequence, although this may be an artefact of the small sample size. Phylogenetic analyses of the morphological data, with and without the morphometric data, yielded unresolved trees. Molecular phylogenetic results found N. benguetensis to be monophyletic, but neither clearly rejected nor supported its validity. Two of our approaches using molecular data diagnosed N. benguetensis, but those that used phenotypic data did not exceed a 75% success rate. We conclude, therefore, that N. benguetensis, despite being a weakly distinct allopatric population, and deserving of additional study, should remain synonymized until further analysis suggests otherwise. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 311–333. 相似文献