Integrative species delimitation reveals cryptic diversity in the southern Appalachian Antrodiaetus unicolor (Araneae: Antrodiaetidae) species complex

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.     

A standardized format for handling data on plasmids,viruses and transposons: The PVT database format

The PVT format described here has been designed to store and retrieve genetic data on plasmids, viruses or transposons with special focus on their applications. Both naturally-occurring and engineered elements can be included in it. A variety of data can be accommodated in fields that are grouped in blocks: name and type of element, database administration, element administration, history, propagation, selection and host, biological properties, cloned insert and applications. The number of fields, now 157, can be expanded as required. Most properties can be described in simple logical fields. The format is organized to permit rapid searches and to facilitate communication between database and user; connection with culture and/or DNA collections is also envisaged and adequate fields for these tasks have been provided. The format allows cross-reference with that originated by the Microbial Information Network Europe (MINE) for computer storage and handling of bacterial or fungal strain data.     

Delimiting species in the genus Otospermophilus (Rodentia: Sciuridae), using genetics,ecology, and morphology

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.     

Genomic data reveal deep genetic structure but no support for current taxonomic designation in a grasshopper species complex

Taxonomy has traditionally relied on morphological and ecological traits to interpret and classify biological diversity. Over the last decade, technological advances and conceptual developments in the field of molecular ecology and systematics have eased the generation of genomic data and changed the paradigm of biodiversity analysis. Here we illustrate how traditional taxonomy has led to species designations that are supported neither by high throughput sequencing data nor by the quantitative integration of genomic information with other sources of evidence. Specifically, we focus on Omocestus antigai and Omocestus navasi, two montane grasshoppers from the Pyrenean region that were originally described based on quantitative phenotypic differences and distinct habitat associations (alpine vs. Mediterranean‐montane habitats). To validate current taxonomic designations, test species boundaries, and understand the factors that have contributed to genetic divergence, we obtained phenotypic (geometric morphometrics) and genome‐wide SNP data (ddRADSeq) from populations covering the entire known distribution of the two taxa. Coalescent‐based phylogenetic reconstructions, integrative Bayesian model‐based species delimitation, and landscape genetic analyses revealed that populations assigned to the two taxa show a spatial distribution of genetic variation that do not match with current taxonomic designations and is incompatible with ecological/environmental speciation. Our results support little phenotypic variation among populations and a marked genetic structure that is mostly explained by geographic distances and limited population connectivity across the abrupt landscapes characterizing the study region. Overall, this study highlights the importance of integrative approaches to identify taxonomic units and elucidate the evolutionary history of species.     

Integrative taxonomy uncovers hidden species diversity in the rheophilic genus Potamometra (Hemiptera: Gerridae)

The genus Potamometra Bianchi, 1896 represents big rheophilic semi-aquatic bugs that typically inhabit middle-altitude mountainous streams. Here, we integrated molecular and morphological data for delimiting species boundaries and understanding the evolutionary history of the genus Potamometra. Twenty-seven complete mitochondrial genomes of Potamometra were sequenced, with samples representing most of the known geographically distributed locations around the Sichuan Basin. The results of different species delimitation methods (ABGD, bPTP, GMYC and BPP) based on the monolocus or multilocus data strongly supported the existence of two cryptic new species (Potamometra anderseni Zheng, Ye & Bu, sp. nov. and Potamometra zhengi Zheng, Ye & Bu, sp. nov.) although more entities were found in the tree-based delimitation methods. The two new species were successfully validated using morphological characters within a detailed taxonomic framework. Phylogenetic analyses supported the reciprocal monophyly of the seven highly node-supported clades, which were matched with the five known species and two new taxa. A novel gene arrangement pattern that two trnF (trnF1 and trnF2) genes separated by an intergenic spacer (IGS) were found in all the species except the sister group of Potamometra berezowskii Bianchi, 1896 and Potamometra linnavuorii Chen, Nieser & Bu, 2016. This gene rearrangement event could be explained by the tandem duplication and random loss (TDRL) model. Our study emphasized that the combination of molecular sequence data, morphological characters and mitochondrial structural information could improve the accuracy of species delimitation.     

Morphology and molecules reveal two new species of Porites (Scleractinia,Poritidae) from the Red Sea and the Gulf of Aden

Two new reef coral species, Porites farasani sp. nov. and Porites hadramauti sp. nov. (Scleractinia, Poritidae), are described from the Red Sea and the Gulf of Aden. Porites farasani sp. nov. only occurs in the Farasan Islands in the southern Red Sea, while P. hadramauti sp. nov. has been collected in the Yemen Hadramaut region in the Gulf of Aden. Both species presented striking in situ differences with respect to other Porites species, and were characterized by small encrusting colonies and unusual polyp colouration. In order to test the genetic distinctiveness of P. farasani sp. nov. and P. hadramauti sp. nov. between each other and with respect to other representatives in the genus Porites, we investigated their evolutionary relationships with eight other morphological species of Porites occurring in the Red Sea and in the Gulf of Aden. Two DNA loci, the mitochondrial putative control region and the nuclear ribosomal ITS region, were sequenced, and three species delimitation approaches based on barcoding threshold (Automated Barcoding Gap Discovery) and coalescence theory (Poisson-Tree process, Generalized Mixed Yule Coalescent) were applied. Phylogenetic and species delimitation analyses were overall concordant, resolving P. farasani sp. nov. and P. hadramauti sp. nov. as two divergent but closely related lineages. Of the other morphologically defined Porites species, three were genetically differentiated (P. rus, P. columnaris and P. fontanesii), but five were genetically indistinguishable. The discovery of two regional endemics confirms the importance of the Red Sea and the Gulf of Aden as regions of high biodiversity and suggests the need for an integration of genome-wide molecular data with the re-evaluation of skeletal structures in the systematics of Porites.     

Integrating genomic and phenotypic data to evaluate alternative phylogenetic and species delimitation hypotheses in a recent evolutionary radiation of grasshoppers

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.     

Phylogeny and species delimitation of the C‐genome diploid species in Oryza

Abstract The diploid Oryza species with C‐genome type possesses abundant genes useful for rice improvement and provides parental donors of many tetraploid species with the C‐genome (BBCC, CCDD). Despite extensive studies, the phylogenetic relationship among the C‐genome species and the taxonomic status of some taxa remain controversial. In this study, we reconstructed the phylogeny of three diploid species with C‐genome (Oryza officinalis, O. rhizomatis, and O. eichingeri) based on sequences of 68 nuclear single‐copy genes. We obtained a fully resolved phylogenetic tree, clearly indicating the sister relationship of O. officinalis and O. rhizomatis, with O. eichingeri being the more divergent lineage. Incongruent phylogenies of the C‐genome species found in previous studies might result from lineage sorting, introgression/hybridization and limited number of genetic markers used. We further applied a recently developed Bayesian species delimitation method to investigate the species status of the Sri Lankan and African O. eichingeri. Analyses of two datasets (68 genes with a single sample, and 10 genes with multiple samples) support the distinct species status of the Sri Lankan and African O. eichingeri. In addition, we evaluated the impact of the number of sampled individuals and loci on species delimitation. Our simulation suggests that sampling multiple individuals is critically important for species delimitation, particularly for closely related species.     

Three ways to distinguish species: using behavioural,ecological, and molecular data to tell apart two closely related ants,Camponotus renggeri and Camponotus rufipes (Hymenoptera: Formicidae)

The closely related Camponotus renggeri and Camponotus rufipes (subgenus Myrmothrix) often live in sympatry in the Brazilian ‘cerrado’ savannah, and are distinguished by nuances in their blackish body colour and by the colour of the legs. Variation in morphological characters, however, makes species separation difficult and it has been suggested that the two species should be merged into one. As appropriate species identification is essential for studies in ecology and evolutionary biology, here we examine how natural history data (habitat preference, nesting biology) and molecular tools (nuclear and mitochondrial markers) perform in distinguishing sympatric populations of C. renggeri and C. rufipes. In our study area, C. rufipes was only seen in cerrado sensu stricto (scrub of shrubs and trees), whereas C. renggeri occurred in cerrado sensu stricto and cerradão (closed woodland). Camponotus renggeri nested underground or in fallen/erect dead trunks, whereas C. rufipes constructed distinctive nests of dry straw. Nest persistence through time was higher in C. rufipes, especially in the hot/rainy season. Nest distribution was random in C. renggeri and aggregated in C. rufipes. Molecular data consistently showed that, regardless of the source of genetic variation, the uppermost hierarchical level of divergence is observed between species, unambiguously differentiating the individuals identified as C. renggeri and C. rufipes as two independent evolutionary lineages. Mitochondrial data throughout the species' geographical ranges further confirmed a consistent genetic divergence between C. renggeri and C. rufipes along their distribution in Brazil. Our integrated approach combining morphological traits with natural history and molecular data confirms that C. renggeri and C. rufipes are valid species that can be separated in our study area relatively well. © 2015 The Linnean Society of London     

Jenynsia lineata species complex,revision and new species description (Cyprinodontiformes: Anablepidae)

The Jenynsia lineata species complex comprises J. lineata from Montevideo, Uruguay and Jenynsia multidentata, from coastal basins of Brazil, Uruguay and Argentina up to 1200 m a.s.l. Taxonomic divisions within this group were tested using three different species delimitation methods, which found the two existing names to be synonyms and revealed a new cryptic species. Jenynsia darwini sp. nov. is distinguished from all congeners by having a unique combination of character states, including the shape of the dorsal postcleithrum (three times higher than wide v. less than two times higher than wide) and female colour pattern in the half of the caudal peduncle with rows of chromatophores segmented in unaligned spots (v. aligned spots forming lines). The new species also differs from J. lineata by having 26 nucleotide substitutions in the mitochondrial gene cytochrome c oxidase I (coI). Phylogenetic analysis of the genus based on morphological characters proposed by previous studies corroborates monophyly of the subgenera Plesiojenynsia and Jenynsia, with the new species being allocated to the subgenus Jenynsia as the sister group of J. lineata.     

imzML--a common data format for the flexible exchange and processing of mass spectrometry imaging data

The application of mass spectrometry imaging (MS imaging) is rapidly growing with a constantly increasing number of different instrumental systems and software tools. The data format imzML was developed to allow the flexible and efficient exchange of MS imaging data between different instruments and data analysis software. imzML data is divided in two files which are linked by a universally unique identifier (UUID). Experimental details are stored in an XML file which is based on the HUPO-PSI format mzML. Information is provided in the form of a 'controlled vocabulary' (CV) in order to unequivocally describe the parameters and to avoid redundancy in nomenclature. Mass spectral data are stored in a binary file in order to allow efficient storage. imzML is supported by a growing number of software tools. Users will be no longer limited to proprietary software, but are able to use the processing software best suited for a specific question or application. MS imaging data from different instruments can be converted to imzML and displayed with identical parameters in one software package for easier comparison. All technical details necessary to implement imzML and additional background information is available at www.imzml.org.     

Integration of molecular, ecological, morphological and endosymbiont data for species delimitation within the Pnigalio soemius complex (Hymenoptera: Eulophidae)

Integrative taxonomy is a recently developed approach that uses multiple lines of evidence such as molecular, morphological, ecological and geographical data to test species limits, and it stands as one of the most promising approaches to species delimitation in taxonomically difficult groups. The Pnigalio soemius complex (Hymenoptera: Eulophidae) represents an interesting taxonomical and ecological study case, as it is characterized by a lack of informative morphological characters, deep mitochondrial divergence, and is susceptible to infection by parthenogenesis‐inducing Rickettsia. We tested the effectiveness of an integrative taxonomy approach in delimiting species within the P. soemius complex. We analysed two molecular markers (COI and ITS2) using different methods, performed multivariate analysis on morphometric data and exploited ecological data such as host–plant system associations, geographical separation, and the prevalence, type and effects of endosymbiont infection. The challenge of resolving different levels of resolution in the data was met by setting up a formal procedure of data integration within and between conflicting independent lines of evidence. An iterative corroboration process of multiple sources of data eventually indicated the existence of several cryptic species that can be treated as stable taxonomic hypotheses. Furthermore, the integrative approach confirmed a trend towards host specificity within the presumed polyphagous P. soemius and suggested that Rickettsia could have played a major role in the reproductive isolation and genetic diversification of at least two species.     

CLADES: A classification‐based machine learning method for species delimitation from population genetic data

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.     

Morphometric and genetic evidence for four species of gentoo penguin

Gentoo penguins (Pygoscelis papua) are found across the Southern Ocean with a circumpolar distribution and notable genetic and morphological variation across their geographic range. Whether this geographic variation represents species‐level diversity has yet to be investigated in an integrative taxonomic framework. Here, we show that four distinct populations of gentoo penguins (Iles Kerguelen, Falkland Islands, South Georgia, and South Shetlands/Western Antarctic Peninsula) are genetically and morphologically distinct from one another. We present here a revised taxonomic treatment including formal nomenclatural changes. We suggest the designation of four species of gentoo penguin: P. papua in the Falkland Islands, P. ellsworthi in the South Shetland Islands/Western Antarctic Peninsula, P. taeniata in Iles Kerguelen, and a new gentoo species P. poncetii, described herein, in South Georgia. These findings of cryptic diversity add to many other such findings across the avian tree of life in recent years. Our results further highlight the importance of reassessing species boundaries as methodological advances are made, particularly for taxa of conservation concern. We recommend reassessment by the IUCN of each species, particularly P. taeniata and P. poncetii, which both show evidence of decline.     

“整合物种概念”和“分化路上的物种”

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。