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 28

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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
;
Amanda B. Quezada-Riera
;
Blanca Rios-Touma
;
María del Carmen Vizcaíno-Barba
;
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.
;
Salazar Valenzuela, David
;
Mebert K.
;
Peñafiel N.
;
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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A mouth full of blood – autohaemorrhaging in three Ecuadorian snakes (Squamata: Colubridae & Tropidophiidae)
(2023)
Rödel M.-O.
;
Loaiza-Lange A.
;
Penner J.
;
Neira-Salamea K.D.
;
Salazar Valenzuela, David
[No abstract available]
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Why Do Some Lineages Radiate While Others Do Not? Perspectives for Future Research on Adaptive Radiations
(2025)
Rishi De-Kayne
;
Rowan Schley
;
Julia M.I. Barth
;
Luke C. Campillo
;
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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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
;
Guayasamin, J.M.
;
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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Venom versatility: Dynamic anticoagulant and procoagulant variations between and within Bothrocophias (toad-head) and basal Bothrops (lance-head) pit vipers
(2025)
Lachlan A. Bourke
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Salazar Valenzuela, David
;
Marco Mancuso
;
Diego R. Quirola
;
Amaru Loaiza-Lange
Pinpointing the emergence of toxicological evolutionary novelties can be challenging. In American pit vipers, anticoagulant venoms are the paradigm, with a notable exception being the genus Bothrops, which are typically procoagulant. A recent study found that the basal Bothrops (B. pictus) is anticoagulant, raising two competing hypotheses: ancestral Bothrops were anticoagulant with procoagulant venom evolving later, or ancestral Bothrops were procoagulant with anticoagulant venom in B. pictus being a derived trait. To help resolve this, we tested venoms of the sister genus Bothrocophias for pathophysiological actions upon blood clotting. The Ecuadorian Bothrocophias venoms (B. campbelli, B. lojanus, and B. microphthalmus) were compared to Bothrops pictus. Both Bothrocophias lojanus and B. pictus inhibited various blood clotting enzymes, but B. pictus was more potently anticoagulant. Intriguingly, B. campbelli and B. microphthalmus were procoagulant. Both B. microphthalmus populations activated prothrombin, but Zamora Chinchipe locality also activated Factors X and VII. Bothrocophias campbelli showed a novel activity, using Factor Va in a calcium-dependent manner as a cofactor to activate prothrombin, the first time this has been shown for any viperid venom. Organismal phylogenetics failed to resolve the relative positions of B. campbelli and B. lojanus, thus we were unable to ascertain the ancestral trait. To resolve this, more phylogenetic research and venom testing with other Bothrocophias species is needed. Neutralisation tests revealed differential efficacy of PoliVal-ICP (Instituto Clodomiro Picado) and Soro Antibotrópico (Instituto Butantan) antivenoms. Together, these findings aid in designing evidence-based clinical-management strategies and provide foundational data for reconstructing venom evolution
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Venom variation in Bothrops asper lineages from North-Western South America
(2020)
Mora-Obando D.
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Salazar Valenzuela, David
;
Pla D.
;
Lomonte B.
;
Guerrero-Vargas J.A.
Bothrops asper is a venomous pitviper that is widely distributed and of clinical importance in Mesoamerica and northern South America, where it is responsible for 50–80% of all envenomations by Viperidae species. Previous work suggests that B. asper has a complex phylogeographic structure, with the existence of multiple evolutionarily distinct lineages, particularly in the inter-Andean valleys of north South America. To explore the impact of the evolutionary history of B. asper on venom composition, we have investigated geographic variation in the venom proteome of this species from the populations from the Pacific side of Ecuador and south-western Colombia. Among the 21 classes of venom components identified, proteins from mainly four major toxin families, snake venom metalloproteases (PI- and PII-SVMP), phospholipases A2 (K49- and D49-PLA2s), serine proteinases (SVSP), and C-type lectins-like (CTL) proteins are major contributors to the geographic variability in venom. Principal component analyses demonstrate significant differences in venom composition between B. asper lineages previously identified through combination of molecular, morphological and geographical data, and provide additional insights into the selection pressures modulating venom phenotypes on a geographic scale. In particular, altitudinal zonation within the Andean mountain range stands out as a key ecological factor promoting diversification in venom. In addition, the pattern of distribution of PLA2 molecules among B. asper venoms complements phylogenetic analysis in the reconstruction of the dispersal events that account for the current biogeographic distribution of the present-day species' phylogroups. Ontogenic variation was also evident among venoms from some Ecuadorian lineages, although this age-related variation was less extreme than reported in B. asper venoms from Costa Rica. The results of our study demonstrate a significant impact of phylogenetic history on venom composition in a pitviper and show how analyses of this variation can illuminate the timing of the cladogenesis and ecological events that shaped the current distribution of B. asper lineages. Biological significance: Bothrops asper, called “the ultimate pitviper” due to its defensive behavior, large body size, and medical importance, represents a species complex that is widely distributed from southern México southwards across north-western South America to north-western Perú. This work reports the characterization of the venom proteomes of B. asper lineages from the Pacific sides of Ecuador and south-western Colombia. Multivariate analyses indicate that variability in venom composition among the B. asper lineages is driven by proteins from four major toxin families, presumably in response to selection pressures created by recent and historical ecological conditions created by geological and climatic events from the Pliocene-Pleistocene to the present along the Central and South American Continental Divide. The emerging biogeographic pattern of venom variation, interpreted in the context of the current phylogenetic hypotheses, support and complement previously proposed evolutionary Plio-Pleistocene dispersal events that shaped the present-day distribution range of B. asper lineages. In addition, our venomics data indicate the occurrence of genetic exchange between Colombian and Pacific Costa Rican populations, which may have occurred during the second wave of B. asper migration into Mesoamerica. Our work represents a foundation for a future broader sampling and more complete “-omics” analyses to deepen our understanding of the patterns and causes of venom variation in this medically important pitviper. © 2020 Elsevier B.V.
Scopus© Citations 21 14
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Neotropics as a Cradle for Adaptive Radiations
(2025)
Juan E. Guevara-Andino
;
Liliana M. Dávalos
;
Felipe Zapata
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María José Endara
;
Darko D. Cotoras
Neotropical ecosystems are renowned for numerous examples of adaptive radiation in both plants and animals resulting in high levels of biodiversity and endemism. However, we still lack a comprehensive review of the abiotic and biotic factors that contribute to these adaptive radiations. To fill this gap, we delve into the geological history of the region, including the role of tectonic events such as the Andean uplift, the formation of the Isthmus of Panama, and the emergence of the Guiana and Brazilian Shields. We also explore the role of ecological opportunities created by the emergence of new habitats, as well as the role of key innovations, such as novel feeding strategies or reproductive mechanisms. We discuss different examples of adaptive radiation, including classic ones like Darwin's finches and Anolis lizards, and more recent ones like bromeliads and lupines. Finally, we propose new examples of adaptive radiations mediated by ecological interactions in their geological context. By doing so, we provide insights into the complex interplay of factors that contributed to the remarkable diversity of life in the Neotropics and highlight the importance of this region in understanding the origins of biodiversity.
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Divergence of tropical pitvipers promoted by independent colonization events of dry montane Andean habitats
(2019)
Salazar Valenzuela, David
;
Kuch U.
;
Torres-Carvajal O.
;
Valencia J.H.
;
Gibbs H.L.
Aim: A poorly explored feature of the origin and maintenance of Neotropical biodiversity is how the evolutionary dynamics of colonization and differentiation in relation to lowland and highland habitats has impacted lineage formation. Most speciation models for this region have focused on vicariant events, whereas the need to assess the influence of demographic processes has been recognized only recently. We evaluate if the origin of Andean montane lineages of terciopelo pitvipers is explained by either of two historical processes that represent distinct phylogeographic mechanisms: differentiation by isolation within the highlands or different dispersal events from the lowlands. Location: Western Ecuador. Taxon: Terciopelo pitvipers (Bothrops asper species complex). Methods: We use genomic data and genetic clustering analyses, evaluation of historical migration between genetic clusters and demographic model selection to investigate recent diversification events in South America using a vertebrate group rarely explored in phylogeographic studies: tropical Andean snakes. Specifically, the origin of two Ecuadorian montane lineages of terciopelo pitvipers was evaluated given ambiguous phylogenetic relationships with the presumably ancestral Pacific lowland lineage. Results: Discrepancies of evolutionary relationships previously obtained with tree-like methods are resolved through the use of modelling approaches. We found strong support for the independent origin of montane lineages based on topologies inferred by maximum-likelihood trees and modelling approaches that take into account possible gene flow. This suggests dispersal rather than in-situ differentiation as the most likely mechanism by which the montane linages originated. Main conclusions: Recent large-scale studies have found support for identifying dispersal events as important drivers of diversification in the Neotropical region. We contribute to these ideas by identifying a fine-scale case in a rarely studied group of animals -Andean snakes- in which river valleys acted as an entrance for the upward colonization of montane dry habitats and subsequent ecological diversification. © 2019 John Wiley & Sons Ltd
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A new species of harlequin toad (Bufonidae: Atelopus) from Amazonian Ecuador
(2024)
Plewnia, Amadeus
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Terán-Valdez, Andrea
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Culebras, Jaime
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Boistel, Renaud
;
Paluh, Daniel J.
For nearly four decades, harlequin toads, genus Atelopus, have suffered unparalleled population declines. While this also results in limited understanding of alphataxonomic relationships, these toads face an urgent need for advances in systematics to inform conservation efforts. However, high intraspecific variation and cryptic diversity have hindered a comprehensive understanding of Atelopus diversity. This is particularly exemplified among Amazonian populations related to A. spumarius, where decades of taxonomic work have not been able yet to unravel relationships between the many forms, while the names coined so far have led to taxonomic confusion leaving numer-ous lineages unnamed. A recent comprehensive phylogenetic study has revealed new insights into the systematics of harlequin toads with an emphasis on Amazonian forms, identifying several unnamed lineages. We here describe one of these evolutionary lineages as a new species, restricted to the Ecuadorian Amazon basin, in an integrative taxonomic approach using molecular, morphological, bioacoustic and larval information. With this, we contribute to a better understanding of Atelopus diversity as the baseline of conservation action.
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Salazar Valenzuela, David

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