Guillermo Orti

Guillermo Orti
George Washington University | GW · Department of Biological Sciences

About

298
Publications
73,231
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10,443
Citations
Citations since 2016
48 Research Items
5147 Citations
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800

Publications

Publications (298)
Article
Full-text available
Body size is an important species trait, correlating with life span, fecundity, and other ecological factors. Over Earth’s geological history, climate shifts have occurred, potentially shaping body size evolution in many clades. General rules attempting to summarize body size evolution include Bergmann’s rule, which states that species reach larger...
Article
This study investigates a contact zone between two silverside fish species (marine Odontesthes argentinensis and freshwater O. bonariensis) in the estuarine Mar Chiquita lagoon along the Atlantic coast in Argentina (MChL), in which intermediate morphs had been reported. It has been suggested that admixture and introgression occur in MChL between th...
Article
Bonytongues (Osteoglossomorpha) constitute an ancient clade of teleost fishes distributed in freshwater habitats throughout the world. The group includes well-known species such as arowanas, featherbacks, pirarucus, and the weakly electric fishes in the family Mormyridae. Their disjunct distribution, extreme morphologies, and electrolocating capabi...
Article
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The charismatic trumpetfishes, goatfishes, dragonets, flying gurnards, seahorses, and pipefishes encompass a recently defined yet extraordinarily diverse clade of percomorph fishes-the series Syngnatharia. This group is widely distributed in tropical and warm-temperate regions, with a great proportion of its extant diversity occurring in the Indo-P...
Article
There is an extensive collection of literature on the taxonomy and phylogenetics of flatfishes (Pleuronectiformes) that extends over two centuries, but consensus on many of their evolutionary relationships remains elusive. Phylogenetic uncertainty stems from highly divergent results derived from morphological and genetic characters, and between var...
Preprint
Full-text available
The repeated evolution of novel life histories correlating with ecological variables offer opportunities to test scenarios of convergence and determinism in genetic, developmental, and metabolic features. Here we leverage the diversity of aplocheiloid killifishes, a clade of teleost fishes that contains over 750 species on three continents. Nearly...
Article
The use of high-throughput sequencing technologies to produce genome-scale datasets was expected to settle some long-standing controversies across the Tree of Life, particularly in areas where short branches occur at deep timescales. Instead, these datasets have often yielded many well-supported but conflicting topologies, and highly variable gene-...
Article
Full-text available
Significance Body shape is a strong predictor of habitat occupation in fishes, which changes rapidly at microevolutionary scales in well-studied freshwater systems such as sticklebacks and cichlids. Deep-bodied forms tend to occur in benthic habitats, while pelagic species typically have streamlined body plans. The recurrent evolution of this patte...
Article
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Exon markers have a long history of use in phylogenetics of ray-finned fishes, the most diverse clade of vertebrates with more than 35,000 species. As the number of published genomes increases, it has become easier to test exons and other genetic markers for signals of ancient duplication events and filter out paralogs that can mislead phylogenetic...
Article
The Amazon and neighboring South American river basins harbor the world's most diverse assemblages of freshwater fishes. One of the most prominent South American fish families is the Serrasalmidae (pacus and piranhas), found in nearly every continental basin. Serrasalmids are keystone ecological taxa, being some of the top riverine predators as wel...
Preprint
Full-text available
The Amazon and neighboring South American river basins harbor the world's most diverse assemblages of freshwater fishes. One of the most prominent South American fish families are the Serrasalmidae (pacus and piranhas), found in nearly every continental basin. Serrasalmids are keystone ecological taxa, being some of the top riverine predators as we...
Preprint
Full-text available
Exon markers have a long history of use in phylogenetics of ray-finned fishes, the most diverse clade of vertebrates with more than 35,000 species. As the number of published genomes increases, it has become easier to test exons and other genetic markers for signals of ancient duplication events and filter out paralogs that can mislead phylogenetic...
Article
Full-text available
Rivers and lake systems in the southern cone of South America have been widely influenced by historic glaciations events, carrying important implications on the evolution of aquatic organisms including prompting transitions between marine and freshwater habitats and by triggering hybridization among incipient species via waterway connectivity and s...
Preprint
Full-text available
Ecological opportunity arising in the aftermath of mass extinction events is thought to be a powerful driver of evolutionary radiations. Here, we assessed how the wake of the Cretaceous-Paleogene (K-Pg) mass extinction shaped diversification dynamics in a clade of mostly marine fishes (Carangaria), which comprises a disparate array of benthic and p...
Article
Full-text available
Phylogenomic studies using genome-wide datasets are quickly becoming the state of the art for systematics and comparative studies, but in many cases, they result in strongly supported incongruent results. The extent to which this conflict is real depends on different sources of error potentially affecting big datasets (assembly, stochastic, and sys...
Article
Kisspeptin receptors are G-Protein-Coupled Receptors that regulate GnRH synthesis and release in vertebrates. Here, we report the gene structure of two kisspeptin receptors (kissr2 and kissr3) in pejerrey fish. Genomic analysis exposed a gene structure with 5 exons and 4 introns for kissr2 and 6 exons and 5 introns for kissr3. Two alternative varia...
Data
(A) Schematic representation of a portion of kissr2 gene in pejerrey showing the primer combinations used in this study. C1: kissr2-Ex3-4-F/kissr2-Ex4-R1, used to specifically amplify kissr2_v1, C2: kissr2-Int3-F/kissr2-Ex4-R, used to specifically amplify v2 isoform and C3: kissr2-Ex3-F/kissr2-Ex4-R, used to determine the presence of both isoforms...
Data
Homology model of the Kissr2. Pejerrey Kiss1 sequence is shown in red.
Data
Summary of alternative splicing due to intron retention and exon deletion detected in kissr3 gene of teleost fish.
Data
Reaction efficiencies slope and correlation r2 values of real-time quantitative PCR assays. The efficiency and conditions for primer sets for kiss2, lhb, and, fshb were already reported in Tovar Bohórquez et al. (29) and Elisio et al. (58).
Data
Homology model of the Kissr3. Pejerrey Kiss2 sequence is shown in red.
Data
Weblogo 3 (http://weblogo.threeplusone.com/) representation of the sequence alignments in teleost fish peptides. (A) Teleost Kiss1-15: pjKiss1-15: QDVSSYNLNSFGLRY. (B) Teleost Kiss2-12: pjKiss2-12: SKFNYNPFGLRF.
Article
Full-text available
Characiformes is an order of freshwater fishes that includes many commercially important and emblematic species from South America and Africa, such as the popular piranhas, hatchetfishes, African tiger fishes and tetras. The order is split into two suborders with a total of 24 families, 282 genera and ca. 2,100 species. Here, we present an expanded...
Article
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Our understanding of phylogenetic relationships among bony fishes has been transformed by analysis of a small number of genes, but uncertainty remains around critical nodes. Genome-scale inferences so far have sampled a limited number of taxa and genes. Here we leveraged 144 genomes and 159 transcriptomes to investigate fish evolution with an unpar...
Article
“Fish-out-of-water” offer ecologists and evolutionary biologists ideal opportunities to study the evolution of stress resistance in vertebrate species. Annual killifishes (Cyprinodontiformes: Aplocheiloidei) constitute one of the most intriguing systems to study fish-out-of-water. “Annual” fishes possess a suite of complex and key features that inc...
Article
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Background Fish classifications, as those of most other taxonomic groups, are being transformed drastically as new molecular phylogenies provide support for natural groups that were unanticipated by previous studies. A brief review of the main criteria used by ichthyologists to define their classifications during the last 50 years, however, reveals...
Article
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Salinity gradients are critical habitat determinants for freshwater organisms. Silverside fishes in the genus Odontesthes have recently and repeatedly transitioned from marine to freshwater habitats, overcoming a strong ecological barrier. Genomic and transcrip-tomic changes involved in this kind of transition are only known for a few model species...
Article
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This study investigates zona pellucida (ZP) ultrastructure in fertilized eggs of annual killifishes (suborder Aplocheiloidei), a group of highly specialized fishes that are able to survive desiccation for several weeks to months before they hatch. Little is known about ZP or chorionic ultrastructure sustaining these life-history modes, so scanning...
Article
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The Patagonian silverside Odontesthes hatcheri is a native fish restricted to streams and lakes of Patagonia (Argentina and Chile). Stocking programs to enhance recreational fisheries in man-made reservoirs have introduced a nonnative, closely-related species (the pejerrey O. bonariensis) in Patagonia almost a century ago, and yet little is known a...
Article
Full-text available
Much progress has been achieved in disentangling evolutionary relationships among species in the tree of life, but some taxonomic groups remain difficult to resolve despite increasing availability of genome-scale data sets. Here we present a practical approach to studying ancient divergences in the face of high levels of conflict, based on explicit...
Article
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Flatfish have the most extreme asymmetric body morphology of vertebrates. During metamorphosis, one eye migrates to the contralateral side of the skull, and this migration is accompanied by extensive craniofacial transformations and simultaneous development of lopsided body pigmentation. The evolution of this developmental and physiological innovat...
Article
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Ray-finned fishes (Actinopterygii) represent more than 50 % of extant vertebrates and are of great evolutionary, ecologic and economic significance, but they are relatively underrepresented in ‘omics studies. Increased availability of transcriptome data for these species will allow researchers to better understand changes in gene expression, and to...
Article
In vertebrates, kisspeptins and their receptors are known to be related to puberty onset and gonadal maturation, however, there are few studies concerning their role in early development. Here, we characterize the kisspeptin system in the pejerrey, Odontesthes bonariensis, a fish with strong temperature-dependent sex determination. We reconstructed...
Article
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Dormancy has evolved in all major metazoan lineages. It is critical for survival when environmental stresses are not conducive to growth, maturation, or reproduction. Embryonic diapause is a form of dormancy where development is reversibly delayed and metabolism is depressed. We report the diapause transcriptome of the annual killifish Nematolebias...
Article
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Background The subfamily Stevardiinae is a diverse and widely distributed clade of freshwater fishes from South and Central America, commonly known as “tetras” (Characidae). The group was named “clade A” when first proposed as a monophyletic unit of Characidae and later designated as a subfamily. Stevardiinae includes 48 genera and around 310 valid...
Article
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The Neotropics harbor the world’s most diverse freshwater fish fauna, with many of these species supporting major commercial, subsistence, or sport fisheries. Knowledge of population genetic structure is available for very few Neotropical fishes, thereby restricting management. To address this need, we examined population genetic variation in mtDNA...
Article
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The marine-freshwater boundary is a major biodiversity gradient and few groups have colonised both systems successfully. Fishes have transitioned between habitats repeatedly, diversifying in rivers, lakes and oceans over evolutionary time. However, their history of habitat colonisation and diversification is unclear based on available fossil and ph...
Article
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Phylogeneticists have long understood that several biological processes can cause a gene tree to disagree with its species tree. In recent years, molecular phylogeneticists have increasingly foregone traditional supermatrix approaches in favor of species tree methods that account for one such source of error, incomplete lineage sorting (ILS). While...
Article
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La distribución original del 'pejerrey' patagónico Odontesthes hatcheri ha sido sometida en las últimas décadas a la introducción de una especie relacionada; el 'pejerrey' Bonaerense Odontesthes bonariensis. Ambas especies coexisten actualmente en algunos lagos y embalses debido a prácticas de siembra y pueden cruzarse y producir progenie híbrida y...
Article
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Time-calibrated phylogenies based on molecular data provide a framework for comparative studies. Calibration methods to combine fossil information with molecular phylogenies are, however, under active development, often generating disagreement about the best way to incorporate paleontological data into these analyses. This study provides an empiric...
Article
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The phylogeny of piranhas, pacus, and relatives (family serrasalmidae) was inferred on the basis of DNA sequences from eleven gene fragments that include the mitochondrial control region plus 10 nuclear genes (two exons and eight introns). The new data were obtained for a representative sampling of 53 specimens, collected from all major South Ameri...
Article
Full-text available
Prochilodus lineatus is a highly migratory fish species that sustains the most important commercial fishery of Paraná-Paraguay basin. Migratory patterns are poorly known and only few population genetic studies are available for this species in the Upper Paraná. To assess genetic population structure, we genotyped a sample of 93 individuals from the...
Article
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Hybridization and introgression have important consequences in evolution, such as increasing the genetic diversity and adaptive potential of a species. One of their most conspicuous footprints is discordance among gene trees or between genes and phenotypes. However, most studies that report introgression fail to disprove the null hypothesis that ge...