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1.
Methods Mol Biol ; 2744: 77-104, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38683312

RESUMEN

Over the past two decades, DNA barcoding has become the most popular exploration approach in molecular taxonomy, whether for identification, discovery, delimitation, or description of species. The present contribution focuses on the utility of DNA barcoding for taxonomic research activities related to species delimitation, emphasizing the following aspects:(1) To what extent DNA barcoding can be a valuable ally for fundamental taxonomic research, (2) its methodological and theoretical limitations, (3) the conceptual background and practical use of pairwise distances between DNA barcode sequences in taxonomy, and (4) the different ways in which DNA barcoding can be combined with complementary means of investigation within a broader integrative framework. In this chapter, we recall and discuss the key conceptual advances that have led to the so-called renaissance of taxonomy, elaborate a detailed glossary for the terms specific to this discipline (see Glossary in Chap. 35 ), and propose a newly designed step-by-step species delimitation protocol starting from DNA barcode data that includes steps from the preliminary elaboration of an optimal sampling strategy to the final decision-making process which potentially leads to nomenclatural changes.


Asunto(s)
Código de Barras del ADN Taxonómico , Código de Barras del ADN Taxonómico/métodos , Clasificación/métodos , Filogenia , Animales , Especificidad de la Especie
2.
Methods Mol Biol ; 2744: 281-296, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38683326

RESUMEN

The overall availability of user-friendly software tools tailored to the analysis of DNA barcodes is limited. Several obvious functions such as detecting and visualizing the DNA barcode gap, the calculation of matrices of pairwise distances at the level of species, or the filtering and decontaminating of sets of sequences based on comparisons with reference databases can typically be carried out only by complex procedures that involve various programs and/or a substantial manual work of formatting. The iTaxoTools project aims at contributing user-friendly software solutions to improve the speed and quality of the workflow of alpha-taxonomy. In this chapter, we provide detailed protocols for the use of a substantially improved version of the tool TaxI2 for distance-based exploration of DNA barcodes. The program calculates genetic distances from prealigned data sets, or based on pairwise alignments, or with an alignment-free approach. Sequence and metadata input can be formatted as tab-delimited files and TaxI2 then computes tables, matrices and graphs of distances, and distance summary statistics within and between species and genera. TaxI2 also includes modes to compare a set of sequences against one or two reference data sets and output lists of best matches or filter data according to thresholds or reciprocal matches. Here, detailed step-by-step protocols are provided for the use of TaxI2, as well as for the interpretation of the program's output.


Asunto(s)
Código de Barras del ADN Taxonómico , Programas Informáticos , Código de Barras del ADN Taxonómico/métodos , Biología Computacional/métodos , ADN/genética
3.
Methods Mol Biol ; 2744: 313-334, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38683328

RESUMEN

DNA barcoding plays an important role in exploring undescribed biodiversity and is increasingly used to delimit lineages at the species level (see Chap. 4 by Miralles et al.). Although several approaches and programs have been developed to perform species delimitation from datasets of single-locus DNA sequences, such as DNA barcodes, most of these were not initially provided as user-friendly GUI-driven executables. In spite of their differences, most of these tools share the same goal, i.e., inferring de novo a partition of subsets, potentially each representing a distinct species. More recently, a proposed common exchange format for the resulting species partitions (SPART) has been implemented by several of these tools, paving the way toward developing an interoperable digital environment entirely dedicated to integrative and comparative species delimitation. In this chapter, we provide detailed protocols for the use of two bioinformatic tools, one for single locus molecular species delimitation (ASAP) and one for statistical comparison of species partitions resulting from any kind of species delimitation analyses (LIMES).


Asunto(s)
Biología Computacional , Código de Barras del ADN Taxonómico , Programas Informáticos , Código de Barras del ADN Taxonómico/métodos , Biología Computacional/métodos , Biodiversidad , Filogenia , Especificidad de la Especie , Animales , Especiación Genética
4.
Methods Mol Biol ; 2744: 297-311, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38683327

RESUMEN

Rapid biodiversity loss sets new requirements for taxonomic research, prompting updating some long-established practices to maximize timely documentation of species before they have gone extinct. One of the crucial procedures associated with the description of new taxa in Linnean taxonomy is assigning them a diagnosis, which is an account of the specific features of the taxon, differentiating it from already described species. Traditionally, diagnostic characters have been morphological, but especially in the case of morphologically cryptic species, molecular diagnoses become increasingly important. In this chapter, we provide detailed protocols for molecular taxon diagnosis with the bioinformatic tool MolD which is available as open-source Python code, command-line driven binary, GUI-driven executable for Windows and Mac, and Galaxy implementation. MolD identifies diagnostic combinations of nucleotides (DNCs) in addition to single (pure) diagnostic sites, enabling users to base DNA diagnoses on a minimal number of diagnostic sites necessary for reliable differentiation of taxa.


Asunto(s)
Biología Computacional , Código de Barras del ADN Taxonómico , Programas Informáticos , Código de Barras del ADN Taxonómico/métodos , Biología Computacional/métodos , Filogenia , Biodiversidad
5.
Brief Bioinform ; 25(2)2024 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-38493344

RESUMEN

Venomous organisms have independently evolved the ability to produce toxins 101 times during their evolutionary history, resulting in over 200 000 venomous species. Collectively, these species produce millions of toxins, making them a valuable resource for bioprospecting and understanding the evolutionary mechanisms underlying genetic diversification. RNA-seq is the preferred method for characterizing toxin repertoires, but the analysis of the resulting data remains challenging. While early approaches relied on similarity-based mapping to known toxin databases, recent studies have highlighted the importance of structural features for toxin detection. The few existing pipelines lack an integration between these complementary approaches, and tend to be difficult to run for non-experienced users. To address these issues, we developed DeTox, a comprehensive and user-friendly tool for toxin research. It combines fast execution, parallelization and customization of parameters. DeTox was tested on published transcriptomes from gastropod mollusks, cnidarians and snakes, retrieving most putative toxins from the original articles and identifying additional peptides as potential toxins to be confirmed through manual annotation and eventually proteomic analysis. By integrating a structure-based search with similarity-based approaches, DeTox allows the comprehensive characterization of toxin repertoire in poorly-known taxa. The effect of the taxonomic bias in existing databases is minimized in DeTox, as mirrored in the detection of unique and divergent toxins that would have been overlooked by similarity-based methods. DeTox streamlines toxin annotation, providing a valuable tool for efficient identification of venom components that will enhance venom research in neglected taxa.


Asunto(s)
Toxinas Biológicas , Ponzoñas , Animales , Ponzoñas/genética , Ponzoñas/química , Proteómica , Toxinas Biológicas/genética , Serpientes , Péptidos , Transcriptoma
6.
Syst Biol ; 2024 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-38456663

RESUMEN

The molluscan order Neogastropoda encompasses over 15,000 almost exclusively marine species playing important roles in benthic communities and in the economies of coastal countries. Neogastropoda underwent intensive cladogenesis in early stages of diversification, generating a 'bush' at the base of their evolutionary tree, that has been hard to resolve even with high throughput molecular data. In the present study to resolve the bush, we use a variety of phylogenetic inference methods and a comprehensive exon capture dataset of 1,817 loci (79.6% data occupancy) comprising 112 taxa of 48 out of 60 Neogastropoda families. Our results show consistent topologies and high support in all analyses at (super)family level, supporting monophyly of Muricoidea, Mitroidea, Conoidea, and, with some reservations, Olivoidea and Buccinoidea. Volutoidea and Turbinelloidea as currently circumscribed are clearly paraphyletic. Despite our analyses consistently resolving most backbone nodes, three prove problematic: First, uncertain placement of Cancellariidae, as the sister group to either a Ficoidea-Tonnoidea clade, or to the rest of Neogastropoda, leaves monophyly of Neogastropoda unresolved. Second, relationships are contradictory at the base of the major 'core Neogastropoda' grouping. Third, coalescence-based analyses reject monophyly of the Buccinoidea in relation to Vasidae. We analysed phylogenetic signal of targeted loci in relation to potential biases, and we propose most probable resolutions in the latter two recalcitrant nodes. The uncertain placement of Cancellariidae may be explained by orthology violations due to differential paralog loss shortly after the whole genome duplication, which should be resolved with a curated set of longer loci.

7.
Mol Phylogenet Evol ; 191: 107969, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38007006

RESUMEN

Taxon sampling in most phylogenomic studies is often based on known taxa and/or morphospecies, thus ignoring undescribed diversity and/or cryptic lineages. The family Turridae is a group of venomous snails within the hyperdiverse superfamily Conoidea that includes many undescribed and cryptic species. Therefore 'traditional' taxon sampling could constitute a strong risk of undersampling or oversampling Turridae lineages. To minimize potential biases, we establish a robust sampling strategy, from species delimitation to phylogenomics. More than 3,000 cox-1 "barcode" sequences were used to propose 201 primary species hypotheses, nearly half of them corresponding to species potentially new to science, including several cryptic species. A 110-taxa exon-capture tree, including species representatives of the diversity uncovered with the cox-1 dataset, was build using up to 4,178 loci. Our results show the polyphyly of the genus Gemmula, that is split into up to 10 separate lineages, of which half would not have been detected if the sampling strategy was based only on described species. Our results strongly suggest that the use of blind, exploratory and intensive barcode sampling is necessary to avoid sampling biases in phylogenomic studies.


Asunto(s)
Código de Barras del ADN Taxonómico , Caracoles , Animales , Filogenia , Caracoles/genética , ADN , Exones
8.
J Mol Evol ; 91(6): 837-853, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-37962577

RESUMEN

Venomous marine gastropods of the family Conidae are among the most diversified predators in marine realm-in large due to their complex venoms. Besides being a valuable source of bioactive neuropeptides conotoxins, cone-snails venoms are an excellent model for molecular evolution studies, addressing origin of key innovations. However, these studies are handicapped by scarce current knowledge on the tissues involved in venom production, as it is generally assumed the sole prerogative of the venom gland (VG). The role of other secretory glands that are present in all Conus species (salivary gland, SG) or only in some species (accessory salivary gland, ASG) remains poorly understood. Here, for the first time, we carry out a detailed analysis of the VG, SG, and ASG transcriptomes in the vermivorous Conus virgo. We detect multiple transcripts clusters in both the SG and ASG, whose annotations imply venom-related functions. Despite the subsets of transcripts highly-expressed in the VG, SG, and ASG being very distinct, SG expresses an L-, and ASG-Cerm08-, and MEFRR- superfamily conotoxins, all previously considered specific for VG. We corroborate our results with the analysis of published SG and VG transcriptomes from unrelated fish-hunting C. geographus, and C. striatus, possibly fish-hunting C. rolani, and worm-hunting Conus quercinus. In spite of low expression levels of conotoxins, some other specific clusters of putative venom-related peptides are present and may be highly expressed in the SG of these species. Further functional studies are necessary to determine the role that these peptides play in envenomation. In the meantime, our results show importance of routine multi-tissue sampling both for accurate interpretation of tissue-specific venom composition in cone-snails, and for better understanding origin and evolution of venom peptides genes.


Asunto(s)
Conotoxinas , Caracol Conus , Animales , Caracol Conus/genética , Caracol Conus/metabolismo , Ponzoñas , Conotoxinas/genética , Conotoxinas/metabolismo , Perfilación de la Expresión Génica , Péptidos/metabolismo
9.
Mol Biol Evol ; 40(8)2023 08 03.
Artículo en Inglés | MEDLINE | ID: mdl-37494290

RESUMEN

The diversity of venomous organisms and the toxins they produce have been increasingly investigated, but taxonomic bias remains important. Neogastropods, a group of marine predators representing almost 22% of the known gastropod diversity, evolved a wide range of feeding strategies, including the production of toxins to subdue their preys. However, whether the diversity of these compounds is at the origin of the hyperdiversification of the group and how genome evolution may correlate with both the compounds and species diversities remain understudied. Among the available gastropods genomes, only eight, with uneven quality assemblies, belong to neogastropods. Here, we generated chromosome-level assemblies of two species belonging to the Tonnoidea and Muricoidea superfamilies (Monoplex corrugatus and Stramonita haemastoma). The two obtained high-quality genomes had 3 and 2.2 Gb, respectively, and 92-89% of the total assembly conformed 35 pseudochromosomes in each species. Through the analysis of syntenic blocks, Hox gene cluster duplication, and synonymous substitutions distribution pattern, we inferred the occurrence of a whole genome duplication event in both genomes. As these species are known to release venom, toxins were annotated in both genomes, but few of them were found in homologous chromosomes. A comparison of the expression of ohnolog genes (using transcriptomes from osphradium and salivary glands in S. haemastoma), where both copies were differentially expressed, showed that most of them had similar expression profiles. The high quality of these genomes makes them valuable reference in their respective taxa, facilitating the identification of genome-level processes at the origin of their evolutionary success.


Asunto(s)
Evolución Molecular , Gastrópodos , Duplicación de Gen , Genoma , Venenos de Moluscos , Gastrópodos/clasificación , Gastrópodos/genética , Genoma/genética , Animales , Cromosomas/genética , Genes Homeobox , Sintenía/genética , Transcriptoma/genética , Venenos de Moluscos/genética
10.
Zool Scr ; 51(5): 550-561, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36245672

RESUMEN

The Neogastropoda (Mollusca, Gastropoda) encompass more than 15,000 described species of marine predators, including several model organisms in toxinology, embryology and physiology. However, their phylogenetic relationships remain mostly unresolved and their classification unstable. We took advantage of the many mitogenomes published in GenBank to produce a new molecular phylogeny of the neogastropods. We completed the taxon sampling by using an in-house bioinformatic pipeline to retrieve mitochondrial genes from 13 transcriptomes, corresponding to five families not represented in GenBank, for a final dataset of 113 taxa. Because mitogenomic data are prone to reconstruction artefacts, eight different evolutionary models were applied to reconstruct phylogenetic trees with IQTREE, RAxML and MrBayes. If the over-parametrization of some models produced trees with aberrant internal long branches, the global topology of the trees remained stable over models and softwares, and several relationships were revealed or found supported here for the first time. However, even if our dataset encompasses 60% of the valid families of neogastropods, some key taxa are missing and should be added in the future before proposing a revision of the classification of the neogastropods. Our study also demonstrates that even complex models struggle to satisfactorily handle the evolutionary history of mitogenomes, still leading to long-branch attractions in phylogenetic trees. Other approaches, such as reduced-genome strategies, must be envisaged to fully resolve the neogastropod phylogeny.

11.
Mol Ecol Resour ; 22(5): 2038-2053, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35094504

RESUMEN

DNA data are increasingly being used for phylogenetic inference, and taxon delimitation and identification, but scarcely for the formal description of taxa, despite their undisputable merits in taxonomy. The uncertainty regarding the robustness of DNA diagnoses, however, remains a major impediment to their use. We have developed a new program, mold, that identifies diagnostic nucleotide combinations (DNCs) in DNA sequence alignments for selected taxa, which can be used to provide formal diagnoses of these taxa. To test the robustness of DNA diagnoses, we carry out iterated haplotype subsampling for selected query species in published DNA data sets of varying complexity. We quantify the reliability of diagnosis by diagnosing each query subsample and then checking if this diagnosis remains valid against the entire data set. We demonstrate that widely used types of diagnostic DNA characters are often absent for a query taxon or are not sufficiently reliable. We thus propose a new type of DNA diagnosis, termed "redundant DNC" (or rDNC), which takes into account unsampled genetic diversity, and constitutes a much more reliable descriptor of a taxon. mold successfully retrieves rDNCs for all but two species in the analysed data sets, even in those comprising hundreds of species. mold shows unparalleled efficiency in large DNA data sets and is the only available software capable of compiling DNA diagnoses that suit predefined criteria of reliability.


Asunto(s)
ADN , Programas Informáticos , Código de Barras del ADN Taxonómico , Filogenia , Reproducibilidad de los Resultados , Alineación de Secuencia
12.
Mol Ecol Resour ; 22(1): 430-438, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34288531

RESUMEN

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.

13.
Proc Biol Sci ; 288(1954): 20211017, 2021 07 14.
Artículo en Inglés | MEDLINE | ID: mdl-34229491

RESUMEN

Marine gastropods of the genus Conus are renowned for their remarkable diversity and deadly venoms. While Conus venoms are increasingly well studied for their biomedical applications, we know surprisingly little about venom composition in other lineages of Conidae. We performed comprehensive venom transcriptomic profiling for Conasprella coriolisi and Pygmaeconus traillii, first time for both respective genera. We complemented reference-based transcriptome annotation by a de novo toxin prediction guided by phylogeny, which involved transcriptomic data on two additional 'divergent' cone snail lineages, Profundiconus, and Californiconus. We identified toxin clusters (SSCs) shared among all or some of the four analysed genera based on the identity of the signal region-a molecular tag present in toxins. In total, 116 and 98 putative toxins represent 29 and 28 toxin gene superfamilies in Conasprella and Pygmaeconus, respectively; about quarter of these only found by semi-manual annotation of the SSCs. Two rare gene superfamilies, originally identified from fish-hunting cone snails, were detected outside Conus rather unexpectedly, so we further investigated their distribution across Conidae radiation. We demonstrate that both these, in fact, are ubiquitous in Conidae, sometimes with extremely high expression. Our findings demonstrate how a phylogeny-aware approach circumvents methodological caveats of similarity-based transcriptome annotation.


Asunto(s)
Conotoxinas , Caracol Conus , Animales , Caracol Conus/genética , Filogenia , Caracoles , Ponzoñas
14.
Mol Ecol Resour ; 21(2): 609-620, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33058550

RESUMEN

Here, we describe Assemble Species by Automatic Partitioning (ASAP), a new method to build species partitions from single locus sequence alignments (i.e., barcode data sets). ASAP is efficient enough to split data sets as large 104 sequences into putative species in several minutes. Although grounded in evolutionary theory, ASAP is the implementation of a hierarchical clustering algorithm that only uses pairwise genetic distances, avoiding the computational burden of phylogenetic reconstruction. Importantly, ASAP proposes species partitions ranked by a new scoring system that uses no biological prior insight of intraspecific diversity. ASAP is a stand-alone program that can be used either through a graphical web-interface or that can be downloaded and compiled for local usage. We have assessed its power along with three others programs (ABGD, PTP and GMYC) on 10 real COI barcode data sets representing various degrees of challenge (from small and easy cases to large and complicated data sets). We also used Monte-Carlo simulations of a multispecies coalescent framework to assess the strengths and weaknesses of ASAP and the other programs. Through these analyses, we demonstrate that ASAP has the potential to become a major tool for taxonomists as it proposes rapidly in a full graphical exploratory interface relevant species hypothesis as a first step of the integrative taxonomy process.


Asunto(s)
Código de Barras del ADN Taxonómico , Programas Informáticos , Algoritmos , Análisis por Conglomerados , Método de Montecarlo , Filogenia , Alineación de Secuencia , Especificidad de la Especie
15.
Mol Phylogenet Evol ; 156: 107040, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33310060

RESUMEN

With 59 Recent species, Bursidae, known as «frog shells¼, are a small but widely distributed group of tropical and subtropical gastropods that are most diverse in the Indo-West Pacific. The present study is aimed at reconstructing phylogenetic relationships of bursid gastropods based on extensive and representative taxon sampling. Five genetic markers (cytochrome c oxidase subunit I (cox1), 16 s and 12 s rRNA mitochondrial genes, 28 s rRNA and Histone H3 nuclear gene) were sequenced for over 30 species in every known genus but Crossata. Furthermore, we sequenced the complete mt-genome of 9 species (10 specimens) (Aspa marginata, Marsupina bufo, Korrigania quirihorai, Korrigania fijiensis, Tutufa rubeta, Bursa lamarckii, Lampasopsis rhodostoma (twice), Bufonaria perelegans and Bursa aff. tuberosissima). Our analysis recovered Bursidae as a monophyletic group, whereas the genus Bursa was found to be polyphyletic. The genera Talisman and Dulcerana are resurrected and the genera Alanbeuella gen. nov. and Korrigania gen. nov. are described. Dating analysis using 21 extinct taxa for node and simplified tip calibrations was performed, showing a diversification of the group in two phases. Diversification may be linked to tectonic events leading to biodiversity relocation from the western Tethys toward the Indo-Pacific.


Asunto(s)
Gastrópodos/clasificación , Gastrópodos/genética , Genoma Mitocondrial , Filogenia , Animales , Teorema de Bayes , Calibración , Fósiles , Genes Mitocondriales , Análisis de Secuencia de ADN , Factores de Tiempo
16.
Syst Biol ; 69(3): 413-430, 2020 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-31504987

RESUMEN

How species diversification occurs remains an unanswered question in predatory marine invertebrates, such as sea snails of the family Terebridae. However, the anatomical disparity found throughput the Terebridae provides a unique perspective for investigating diversification patterns in venomous predators. In this study, a new dated molecular phylogeny of the Terebridae is used as a framework for investigating diversification of the family through time, and for testing the putative role of intrinsic and extrinsic traits, such as shell size, larval ecology, bathymetric distribution, and anatomical features of the venom apparatus, as drivers of terebrid species diversification. Macroevolutionary analysis revealed that when diversification rates do not vary across Terebridae clades, the whole family has been increasing its global diversification rate since 25 Ma. We recovered evidence for a concurrent increase in diversification of depth ranges, while shell size appeared to have undergone a fast divergence early in terebrid evolutionary history. Our data also confirm that planktotrophy is the ancestral larval ecology in terebrids, and evolutionary modeling highlighted that shell size is linked to larval ecology of the Terebridae, with species with long-living pelagic larvae tending to be larger and have a broader size range than lecithotrophic species. Although we recovered patterns of size and depth trait diversification through time and across clades, the presence or absence of a venom gland (VG) did not appear to have impacted Terebridae diversification. Terebrids have lost their venom apparatus several times and we confirm that the loss of a VG happened in phylogenetically clustered terminal taxa and that reversal is extremely unlikely. Our findings suggest that environmental factors, and not venom, have had more influence on terebrid evolution.


Asunto(s)
Organismos Acuáticos/clasificación , Biodiversidad , Evolución Biológica , Ambiente , Filogenia , Caracoles/clasificación , Animales
17.
Mol Phylogenet Evol ; 142: 106660, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31639524

RESUMEN

For over a decade now, High Throughput sequencing (HTS) approaches have revolutionized phylogenetics, both in terms of data production and methodology. While transcriptomes and (reduced) genomes are increasingly used, generating and analyzing HTS datasets remain expensive, time consuming and complex for most non-model taxa. Indeed, a literature survey revealed that 74% of the molecular phylogenetics trees published in 2018 are based on data obtained through Sanger sequencing. In this context, our goal was to identify the strategy that would represent the best compromise among costs, time and robustness of the resulting tree. We sequenced and assembled 32 transcriptomes of the marine mollusk family Turridae, considered as a typical non-model animal taxon. From these data, we extracted the loci most commonly used in gastropod phylogenies (cox1, 12S, 16S, 28S, h3 and 18S), full mitogenomes, and a reduced nuclear transcriptome representation. With each dataset, we reconstructed phylogenies and compared their robustness and accuracy. We discuss the impact of missing data and the use of statistical tests, tree metrics, and supertree and supermatrix methods to further improve phylogenetic data acquisition pipelines. We evaluated the overall costs (time and money) in order to identify the best compromise for phylogenetic data sampling in non-model animal taxa. Although sequencing full mitogenomes seems to constitute the best compromise both in terms of costs and node support, they are known to induce biases in phylogenetic reconstructions. Rather, we recommend to systematically include loci commonly used for phylogenetics and taxonomy (i.e. DNA barcodes, rRNA genes, full mitogenomes, etc.) among the other loci when designing baits for capture.


Asunto(s)
Filogenia , Animales , Costos y Análisis de Costo , Perfilación de la Expresión Génica , Genoma , Secuenciación de Nucleótidos de Alto Rendimiento , Moluscos/clasificación , Moluscos/genética , Análisis de Secuencia de ADN
18.
Toxins (Basel) ; 11(11)2019 10 28.
Artículo en Inglés | MEDLINE | ID: mdl-31661832

RESUMEN

Profundiconus is the most divergent cone snail genus and its unique phylogenetic position, sister to the rest of the family Conidae, makes it a key taxon for examining venom evolution and diversity. Venom gland and foot transcriptomes of Profundiconus cf. vaubani and Profundiconusneocaledonicus were de novo assembled, annotated, and analyzed for differential expression. One hundred and thirty-seven venom components were identified from P. cf. vaubani and 82 from P. neocaledonicus, with only four shared by both species. The majority of the transcript diversity was composed of putative peptides, including conotoxins, profunditoxins, turripeptides, insulin, and prohormone-4. However, there were also a significant percentage of other putative venom components such as chymotrypsin and L-rhamnose-binding lectin. The large majority of conotoxins appeared to be from new gene superfamilies, three of which are highly different from previously reported venom peptide toxins. Their low conotoxin diversity and the type of insulin found suggested that these species, for which no ecological information are available, have a worm or molluscan diet associated with a narrow dietary breadth. Our results indicate that Profundiconus venom is highly distinct from that of other cone snails, and therefore important for examining venom evolution in the Conidae family.


Asunto(s)
Evolución Biológica , Conotoxinas/genética , Conotoxinas/toxicidad , Caracol Conus/química , Caracol Conus/genética , Variación Genética , Animales
19.
Sci Rep ; 9(1): 7846, 2019 05 24.
Artículo en Inglés | MEDLINE | ID: mdl-31127123

RESUMEN

Species delimitation in minute freshwater snails is often difficult to perform using solely shell morphology. The problem intensifies when invasive species spread within the distribution range of morphologically similar native species. In Chile, the Truncatelloidean snails are represented by the native genera Heleobia and Potamolithus plus the invasive mudsnail Potamopyrgus antipodarum, which can easily be confused. Using an integrative approach, we performed molecular phylogenetic analysis and studied reproductive and morphological features to identify superficially similar forms inhabiting the central area of the country. Truncatelloidean snails were identified in 40 of 51 localities sampled, 10 containing Potamopyrgus antipodarum, 23 Heleobia and 7 Potamolithus. Based on these results and previously published data, the known distribution of the mudsnail in Chile encompasses 6 hydrological basins, including 18 freshwater ecosystems. The finding of the mudsnails in several type localities of native species/subspecies of "Heleobia" that were not find in situ suggests species replacement or significant extinction of native fauna, a hypothesis supported by the restudy of type material that shows that endemic forms belong to the genus Potamolithus. This study shows the usefulness of integrative taxonomy not only resolving complex taxa with cryptic morphology but also measuring the extent of an ongoing invasion.


Asunto(s)
Seguimiento de Parámetros Ecológicos/métodos , Especies Introducidas , Reproducción/genética , Caracoles/clasificación , Animales , Chile , Complejo IV de Transporte de Electrones/genética , Estudios de Factibilidad , Femenino , Agua Dulce , Masculino , Filogenia , Análisis de Secuencia de ADN , Caracoles/anatomía & histología , Caracoles/genética
20.
Syst Biol ; 68(5): 781-796, 2019 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-30816949

RESUMEN

Understanding why some groups of organisms are more diverse than others is a central goal in macroevolution. Evolvability, or the intrinsic capacity of lineages for evolutionary change, is thought to influence disparities in species diversity across taxa. Over macroevolutionary time scales, clades that exhibit high evolvability are expected to have higher speciation rates. Cone snails (family: Conidae, $>$900 spp.) provide a unique opportunity to test this prediction because their toxin genes can be used to characterize differences in evolvability between clades. Cone snails are carnivorous, use prey-specific venom (conotoxins) to capture prey, and the genes that encode venom are known and diversify through gene duplication. Theory predicts that higher gene diversity confers a greater potential to generate novel phenotypes for specialization and adaptation. Therefore, if conotoxin gene diversity gives rise to varying levels of evolvability, conotoxin gene diversity should be coupled with macroevolutionary speciation rates. We applied exon capture techniques to recover phylogenetic markers and conotoxin loci across 314 species, the largest venom discovery effort in a single study. We paired a reconstructed timetree using 12 fossil calibrations with species-specific estimates of conotoxin gene diversity and used trait-dependent diversification methods to test the impact of evolvability on diversification patterns. Surprisingly, we did not detect any signal for the relationship between conotoxin gene diversity and speciation rates, suggesting that venom evolution may not be the rate-limiting factor controlling diversification dynamics in Conidae. Comparative analyses showed some signal for the impact of diet and larval dispersal strategy on diversification patterns, though detection of a signal depended on the dataset and the method. If our results remain true with increased taxonomic sampling in future studies, they suggest that the rapid evolution of conid venom may cause other factors to become more critical to diversification, such as ecological opportunity or traits that promote isolation among lineages.


Asunto(s)
Conotoxinas/genética , Gastrópodos/clasificación , Variación Genética , Animales , Evolución Biológica , Gastrópodos/genética , Especiación Genética
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