Salazar Valenzuela, David

Preferred name

Main Affiliation

Centro de Investigación de la Biodiversidad y Cambio Climático

Quito

davidsalazar@uti.edu.ec

ORCID

0000-0002-3874-7690

Scopus Author ID

26644312900

Now showing 1 - 10 of 29

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From smartphones to satellites: Integrating citizen science and high-resolution environmental data for mapping plant invasions in urban mountain landscapes
(Elsevier BV, 2026-11)
Bonilla Bedoya, Santiago
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Salazar-Valenzuela, David
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Oleas Gallo, Nora Helena
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Buenaño, María Belén
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Quijano-Abril, Mario
Predicting the distribution of invasive species in urban mountain ecosystems is important for biodiversity conservation and effective management. We developed a sequential two-stage species distribution modelling framework to characterize habitat suitability for the invasive vine Thunbergia alata in the Metropolitan District of Quito and to evaluate the contribution of citizen science records, systematic field surveys, and multi-source environmental data. In the first stage, 637 iNaturalist occurrence records retained after quality control were combined with 12 bioclimatic variables from WorldClim to develop a preliminary MaxEnt model. The resulting habitat suitability map was classified into five categories and used to design a stratified field survey across the predicted suitability gradient. We sampled 1009 locations, obtaining 450 confirmed presences and 559 independent absence records. In the second stage, the field-derived occurrence data were used to develop a refined MaxEnt model incorporating the bioclimatic variables together with elevation, slope, land cover, VIIRS nighttime lights, NDVI, and the red spectral band. Environmental predictors were standardized to a common 5 m. spatial resolution and screened for multicollinearity. Both models were evaluated using receiver-operating characteristic analyses and AUC, with 10 replicate runs and 25% of occurrence records withheld for testing. Mean AUC values were 0.851 ± 0.012 and 0.902 ± 0.008 for the preliminary and refined models, respectively. In the preliminary model, habitat suitability was primarily associated with broad-scale climatic variables, particularly precipitation seasonality and temperature-related variables. In the refined model, nighttime light intensity and elevation showed the highest contributions and permutation importance, while NDVI and climatic variables also contributed to model predictions. Independent field validation showed that 47.2% of absence observations occurred in the two lowest suitability classes, whereas 33.5% occurred in areas classified as highly or very highly suitable. The refined model therefore captured substantial spatial variation in habitat suitability while also revealing areas of mismatch between predicted suitability and field observations. These results demonstrate the value of sequentially integrating citizen science, systematic field observations, and fine-resolution environmental predictors to improve invasive species mapping. This framework provides a practical approach for supporting targeted monitoring and management of invasive plants in complex urban mountain ecosystems. © 2026 The Authors.
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Dual Effects of a Bothrops asper Phospholipase A₂: Anti-Vibrio Properties and Shrimp Hemocyte Cytotoxicity
(Springer Science and Business Media LLC, 2026-06-30)
Patiño, Ricardo S. P.
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Salazar Valenzuela, David
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Mendes, Bruno
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Bustamante, Kathya
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Hernández-Altamirano, Josselin A.
Emerging antibiotic-resistant Vibrio spp. strains have caused recurrent outbreaks, resulting in substantial losses in shrimp farming and aquaculture production. This ongoing crisis calls for innovative strategies to mitigate its impact, particularly in resource-limited countries that depend heavily on the shrimp industry. In this context, biodiscovery initiatives focused on snake venom toxins with antimicrobial properties represent a promising alternative. Accordingly, we investigated the anti-Vibrio activity of a catalytically inactive phospholipase A₂ (Lys49 PLA₂) purified from the venom of Bothrops asper, a venomous snake commonly found in Ecuador. This novel bioactive biomacromolecule, termed BaETx, was isolated from a venom pool using a one-step purification approach. Mass spectrometry analysis revealed a molecular mass of 13.6 kDa, consistent with its electrophoretic mobility in one-dimensional SDS-PAGE. Structurally, BaETx exhibits high similarity to the amino acid sequences of PLA₂s previously reported from B. asper venoms in other geographical regions. Bioactivity screening demonstrated that BaETx significantly inhibited the in vitro growth of three Gram-negative Vibrio spp. pathogens. Further mechanistic insights obtained through electron and fluorescence microscopy suggest a membrane-damaging actitvity. However, BaETx also significantly reduced shrimp hemocyte viability, indicating non-selective action and limiting its direct application in aquaculture. In addition, computational sequence analysis identified cationic antimicrobial fragments that warrant further investigation. Overall, this study reports the first purification and characterization of an antimicrobial protein from Ecuadorian snake venom, highlighting its potential as a molecular template for the development of shorter and more selective synthetic peptides targeting white shrimp pathogens. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2026.
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Path for recovery: an ecological overview of the Jambato Harlequin Toad (Bufonidae: <i>Atelopus ignescens</i>) in its last known locality, Angamarca Valley, Ecuador
(2024)
Mateo A. Vega-Yánez
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Amanda B. Quezada-Riera
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Blanca Rios-Touma
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María del Carmen Vizcaíno-Barba
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William Millingalli
The Jambato Harlequin toad (<jats:italic>Atelopus ignescens</jats:italic>), a formerly abundant species in the Andes of Ecuador, faced a dramatic population decline in the 1980s, with its last recorded sighting in 1988. The species was considered Extinct by the IUCN until 2016, when a fortuitous discovery of one Jambato by a local boy reignited hope. In this study, we present findings from an investigation conducted in the Angamarca parish, focusing on distribution, abundance, habitat preferences, ecology, disease susceptibility, and dietary habits of the species. In one year we identified 71 individuals at different stages of development in various habitats, with a significant presence in agricultural mosaic areas and locations near water sources used for crop irrigation, demonstrating the persistence of the species in a complex landscape, with considerable human intervention. The dietary analysis based on fecal samples indicated a diverse prey selection, primarily comprising arthropods such as Acari, Coleoptera, and ants. Amphibian declines have been associated with diseases and climate change; notably, our study confirmed the presence of the pathogen <jats:italic>Batrachochytrium dendrobatidis</jats:italic> (<jats:italic>Bd</jats:italic>), but, surprisingly, none of the infected Jambatos displayed visible signs of illness. When analyzing climatic patterns, we found that there are climatic differences between historical localities and Angamarca; the temporal analysis also exposes a generalized warming trend. Finally, in collaboration with the local community, we developed a series of management recommendations for terrestrial and aquatic environments occupied by the Jambato.
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Systematics of south american snail-eating snakes (Serpentes, dipsadini), with the description of five new species from ecuador and peru
(2018)
Arteaga A.
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Salazar Valenzuela, David
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Mebert K.
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Peñafiel N.
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Aguiar G.
A molecular phylogeny of the Neotropical snail-eating snakes (tribe Dipsadini) is presented including 43 (24 for the first time) of the 77 species, sampled for both nuclear and mitochondrial genes. Morphological and phylogenetic support was found for four new species of Dipsas and one of Sibon, which are described here based on their unique combination of molecular, meristic, and color pattern characteristics. Sibynomorphus is designated as a junior subjective synonym of Dipsas. Dipsas latifrontalis and D. palmeri are resurrected from the synonymy of D. peruana. Dipsas latifasciata is transferred from the synonymy of D. peruana to the synonymy of D. palmeri. A new name, D. jamespetersi, is erected for the taxon currently known as Sibynomorphus petersi. Re-descriptions of D. latifrontalis and D. peruana are presented, as well as the first photographic voucher of an adult specimen of D. latifrontalis, along with photographs of all known Ecuadorian Dipsadini species. The first country record of D. variegata in Ecuador is provided and D. oligozonata removed from the list of Peruvian herpetofauna. With these changes, the number of Dipsadini reported in Ecuador increases to 22, 18 species of Dipsas and four of Sibon. © 2018, Pensoft Publishers. All rights reserved.
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Why Do Some Lineages Radiate While Others Do Not? Perspectives for Future Research on Adaptive Radiations
(2025)
Rishi De-Kayne
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Rowan Schley
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Julia M.I. Barth
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Luke C. Campillo
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Catalina Chaparro-Pedraza
Understanding the processes that drive phenotypic diversification and underpin speciation is key to elucidating how biodiversity has evolved. Although these processes have been studied across a wide array of clades, adaptive radiations (ARs), which are systems with multiple closely related species and broad phenotypic diversity, have been particularly fruitful for teasing apart the factors that drive and constrain diversification. As such, ARs have become popular candidate study systems for determining the extent to which ecological features, including aspects of organisms and the environment, and inter- and intraspecific interactions, led to evolutionary diversification. Despite substantial past empirical and theoretical work, understanding mechanistically how ARs evolve remains a major challenge. Here, we highlight a number of understudied components of the environment and of lineages themselves, which may help further our understanding of speciation and AR. We also outline some substantial remaining challenges to achieving a detailed understanding of adaptation, speciation, and the role of ecology in these processes. These major challenges include identifying factors that have a causative impact in promoting or constraining ARs, gaining a more holistic understanding of features of organisms and their environment that interact resulting in adaptation and speciation, and understanding whether the role of these organismal and environmental features varies throughout the radiation process. We conclude by providing perspectives on how future investigations into the AR process can overcome these challenges, allowing us to glean mechanistic insights into adaptation and speciation. This record is sourced from MEDLINE/PubMed, a database of the U.S. National Library of Medicine
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First Insights into the Venom Composition of Two Ecuadorian Coral Snakes
(2022)
Hernández-Altamirano, J.A.
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Salazar Valenzuela, David
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Medina-Villamizar, E.J.
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Quirola, D.R.
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Patel, K.
Micrurus is a medically relevant genus of venomous snakes composed of 85 species. Bites caused by coral snakes are rare, but they are usually associated with very severe and life-threatening clinical manifestations. Ecuador is a highly biodiverse country with a complex natural environment, which is home to approximately 20% of identified Micrurus species. Additionally, it is on the list of Latin American countries with the highest number of snakebites. However, there is no local antivenom available against the Ecuadorian snake venoms, and the biochemistry of these venoms has been poorly explored. Only a limited number of samples collected in the country from the Viperidae family were recently characterised. Therefore, this study addressed the compositional patterns of two coral snake venoms from Ecuador, M. helleri and M. mipartitus, using venomics strategies, integrating sample fractionation, gel electrophoresis, and mass spectrometry. Chromatographic and electrophoretic profiles of these snake venoms revealed interspecific variability, which was ascertained by mass spectrometry. The two venoms followed the recently recognised dichotomic toxin expression trends displayed by Micrurus species: M. helleri venom contains a high proportion (72%) of phospholipase A2, whereas M. mipartitus venom is dominated by three-finger toxins (63%). A few additional protein families were also detected in these venoms. Overall, these results provide the first comprehensive views on the composition of two Ecuadorian coral snake venoms and expand the knowledge of Micrurus venom phenotypes. These findings open novel perspectives to further research the functional aspects of these biological cocktails of PLA2s and 3FTxs and stress the need for the preclinical evaluation of the currently used antivenoms for therapeutic purposes in Ecuador. © 2022 by the authors.
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A mouth full of blood – autohaemorrhaging in three Ecuadorian snakes (Squamata: Colubridae & Tropidophiidae)
(2023)
Rödel M.-O.
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Loaiza-Lange A.
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Penner J.
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Neira-Salamea K.D.
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Salazar Valenzuela, David
[No abstract available]
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Feeding ecology of the Terciopelo pit viper snake (Bothrops asper) in Ecuador
(2023)
Loaiza-Lange A.
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Székely D
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Torres-Carvajal O.
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Tinoco N.
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Salazar Valenzuela, David
Thoroughly documenting prey items and diet composition is crucial for understanding a predator’s role in the ecosystem. In gape restricted predators, such as snakes, documenting and analyzing the type and size of the prey is important to interpret their ecological role. We describe the diet patterns of a species of venomous snake, the Terciopelo pit viper (Bothrops asper), from its Ecuadorian populations. Examining the gastrointestinal contents of museum specimens collected over an extensive area of the Pacific lowlands of Ecuador, we encountered 69 identifiable prey items from four major taxonomic groups (amphibians, centipedes, mammals, and reptiles). We evaluated the observed composition of prey to check for differences between sexes and size-classes. To complement our observations of the Terciopelo species complex throughout their distribution, we carried out a systematic literature review. Our data show an ontogenetic shift in diet, with a transition from more diverse diet in juveniles towards a mammal-specialized diet in adults, and distinct proportion of prey taxa between the sexes in the juvenile size class. Copyright 2023 Loaiza-Lange et al.
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Harlequin frog rediscoveries provide insights into species persistence in the face of drastic amphibian declines
(2022)
Jaynes, K.E.
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Páez-Vacas, M.I.
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Salazar Valenzuela, David
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Guayasamin, J.M.
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Terán-Valdez, A.
Amphibians face global declines, and it remains unclear the extent to which species have responded, and through what mechanisms, to persist in the face of emerging diseases and climate change. In recent years, the rediscovery of species considered possibly extinct has sparked public and scientific attention. These are hopeful cases in an otherwise bleak story. Yet, we know little about the population status of these rediscovered species, or the biology underlying their persistence. Here, we highlight the iconic Harlequin frogs (Bufonidae: Atelopus) as a system that was devastated by declines but now encompasses between 18 and 32 rediscoveries (25–37 % of possible extinctions) in the last two decades. Geographic distributions of rediscoveries closely match regional described species abundance, and rediscoveries are documented at elevations from 100 m to >3500 m, with no significant differences between mean historical and contemporary elevations. We also provide genomic data on six decimated species, with historical sample comparisons for two of the species and find a pattern of decreasing genetic variation the longer a species had been missing. Further, we document marked decrease in heterozygosity in one species, but not the other, indicating potential idiosyncratic consequences of declines. Finally, we discuss research priorities to guide the potential transition from amphibian declines to recoveries and to maximize conservation efforts. © 2022 The Authors
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Bothrops atrox from Ecuadorian Amazon: Initial analyses of venoms from individuals
(2021)
Patiño R.S.P.
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Salazar Valenzuela, David
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Medina-Villamizar E.
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Mendes B.
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Proaño-Bolaños C.
Bothrops atrox is the most clinically relevant snake species within the Amazon region, which includes Ecuadorian territories. It comprises a large distribution, which could contribute to the genetic and venomic variation identified in the species. The high variability and protein isoform diversity of its venom are of medical interest, since it can influence the clinical manifestations caused by envenomation and its treatment. However, in Ecuador there is insufficient information on the diversity of venomic phenotypes, even of relevant species such as B. atrox. Here, we characterized the biochemical and toxicological profiles of the venom of six B. atrox individuals from the Ecuadorian Amazon. Differences in catalytic activities of toxins, elution profiles in liquid chromatography, electrophoretic patterns, and toxic effects among the analyzed samples were identified. Nonetheless, in the preclinical testing of antivenom, two samples from Mera (Pastaza) required a higher dose to achieve total neutralization of lethality and hemorrhage. Taken together, these data highlight the importance of analyzing individual venoms in studies focused on the outcomes of envenoming. © 2021 Elsevier Ltd
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Salazar Valenzuela, David

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