Browsing by Autor "Carla Maldonado"

Now showing 1 - 20 of 27

A highly contiguous, scaffold-level nuclear genome assembly for the Fever tree ( Cinchona pubescens Vahl) as a novel resource for research in the Rubiaceae
(2022) Nataly Allasi Canales; Oscar A. Pérez‐Escobar; Robyn F. Powell; Mats Töpel; Catherine Kidner; Mark Nesbitt; Carla Maldonado; Christopher J. Barnes; Nina Rønsted; Natalia A. S. Przelomska
Abstract Background The Andean Fever tree ( Cinchona L.; Rubiaceae) is the iconic source of bioactive quinine alkaloids, which have been vital to treating malaria for centuries. C. pubescens Vahl, in particular, has been an essential source of income for several countries within its native range in north-western South America. However, an absence of available genomic resources is essential for placing the Cinchona species within the tree of life and setting the foundation for exploring the evolution and biosynthesis of quinine alkaloids. Findings We address this gap by providing the first highly contiguous and annotated nuclear and organelle genome assemblies for C. pubescens . Using a combination of ∼120 Gb of long sequencing reads derived from the Oxford Nanopore PromethION platform and 142 Gb of short-read Illumina data. Our nuclear genome assembly comprises 603 scaffolds comprising a total length of 904 Mb, and the completeness represents ∼85% of the genome size (1.1 Gb/1C). This draft genome sequence was complemented by annotating 72,305 CDSs using a combination of de novo and reference-based transcriptome assemblies. Completeness analysis revealed that our assembly is moderately complete, displaying 83% of the BUSCO gene set and a small fraction of genes (4.6%) classified as fragmented. Additionally, we report C. pubescens plastome with a length of ∼157 Kb and a GC content of 37.74%. We demonstrate the utility of these novel genomic resources by placing C. pubescens in the Gentianales order using additional plastid and nuclear datasets. Conclusions Our study provides the first genomic resource for C. pubescens , thus opening new research avenues, including the provision of crucial genetic resources for analysis of alkaloid biosynthesis in the Fever tree.
A highly contiguous, scaffold-level nuclear genome assembly for the fever tree (Cinchona pubescens Vahl) as a novel resource for Rubiaceae research
(2022) Nataly Allasi Canales; Oscar A. Pérez‐Escobar; Robyn F. Powell; Mats Töpel; Catherine Kidner; Mark Nesbitt; Carla Maldonado; Christopher J. Barnes; Nina Rønsted; Natalia A. S. Przelomska
The Andean fever tree (Cinchona L.; Rubiaceae) is a source of bioactive quinine alkaloids used to treat malaria. C. pubescens Vahl is a valuable cash crop within its native range in northwestern South America, however, genomic resources are lacking. Here we provide the first highly contiguous and annotated nuclear and plastid genome assemblies using Oxford Nanopore PromethION-derived long-read and Illumina short-read data. Our nuclear genome assembly comprises 603 scaffolds with a total length of 904 Mbp (∼82% of the full genome based on a genome size of 1.1 Gbp/1C). Using a combination of de novo and reference-based transcriptome assemblies we annotated 72,305 coding sequences comprising 83% of the BUSCO gene set and 4.6% fragmented sequences. Using additional plastid and nuclear datasets we place C. pubescens in the Gentianales order. This first genomic resource for C. pubescens opens new research avenues, including the analysis of alkaloid biosynthesis in the fever tree.
Alkaloid Profile Characterisation and Bioactivity Evaluation of Bolivian Hippeastrum Species (Amaryllidaceae) as Cholinesterase Inhibitors
(Multidisciplinary Digital Publishing Institute, 2025) María Lenny Rodríguez-Escobar; Rogéria Inês Rosa Lara; Margoth Atahuachi Burgos; A C.; Carla Maldonado; Jaume Bastida; Luciana R. Tallini; Laura Torras‐Claveria
Amaryllidaceae alkaloids from the Amaryllidoideae subfamily exhibit broad pharmacological activities, including neuroprotection and anticancer effects. Galanthamine is a key compound for Alzheimer's therapy. The Hippeastrum genus, particularly in Bolivia, offers significant potential for novel drug discovery, emphasising the need for conservation and further phytochemical research. Twenty-seven samples from Bolivian Hippeastrum species were investigated in terms of their alkaloid profile and anticholinesterase activity. The phytochemical analysis of Bolivian Hippeastrum species via GC-MS identified 48 Amaryllidaceae alkaloids, displaying diverse structural groups with potential pharmacological significance. Lycorine- and Homolycorine-type alkaloids were predominant, particularly in H. chionedyanthum and H. haywardii, with high concentrations of lycorine, a promising anticancer compound. The species H. evansiarum and H. mollevillquense contained notable quantities of Galanthamine type alkaloids, relevant for Alzheimer's treatment. This study also highlights variability in acetylcholinesterase and butyrylcholinesterase inhibitory activities, with H. lara-ricoi and H. haywardii demonstrating strong inhibition. These findings suggest that Hippeastrum species are a valuable source of bioactive compounds, warranting further research into their therapeutic applications.
CARLA MALDONADO, FINN BORCHSENIUS &amp; CHARLOTTE M. TAYLOR
(Q15088586, 2014) Carla Maldonado; Finn Borchsenius; Charlotte M. Taylor
The new species Elaeagia coriacea (Condamineeae, Rubiaceae), from southern Ecuador, is here described and illustrated. It differs from Elaeagia ecuadorensis in its abaxially papillate leaves and by the short obtuse calyx lobes.
Caught in the Act: Incipient Speciation at the Southern Limit of Viburnum in the Central Andes
(Oxford University Press, 2024) Carlos A. Maya‐Lastra; Patrick W. Sweeney; Deren A. R. Eaton; Vania Torrez; Carla Maldonado; Malu I. Ore-Rengifo; Mónica Arakaki; Michael J. Donoghue; Erika J. Edwards
A fundamental objective of evolutionary biology is to understand the origin of independently evolving species. Phylogenetic studies of species radiations rarely are able to document ongoing speciation; instead, modes of speciation, entailing geographic separation and/or ecological differentiation, are posited retrospectively. The Oreinotinus clade of Viburnum has radiated recently from north to south through the cloud forests of Mexico and Central America to the Central Andes. Our analyses support a hypothesis of incipient speciation in Oreinotinus at the southern edge of its geographic range, from central Peru to northern Argentina. Although several species and infraspecific taxa have been recognized in this area, multiple lines of evidence and analytical approaches (including analyses of phylogenetic relationships, genetic structure, leaf morphology, and climatic envelopes) favor the recognition of just a single species, V. seemenii. We show that what has previously been recognized as V. seemenii f. minor has recently occupied the drier Tucuman-Bolivian forest region from Samaipata in Bolivia to Salta in northern Argentina. Plants in these populations form a well-supported clade with a distinctive genetic signature and they have evolved smaller, narrower leaves. We interpret this as the beginning of a within-species divergence process that has elsewhere in the neotropics resulted repeatedly in Viburnum species with a particular set of leaf ecomorphs. Specifically, the southern populations are in the process of evolving the small, glabrous, and entire leaf ecomorph that has evolved in four other montane areas of endemism. As predicted based on our studies of leaf ecomorphs in Chiapas, Mexico, these southern populations experience generally drier conditions, with large diurnal temperature fluctuations. In a central portion of the range of V. seemenii, characterized by wetter climatic conditions, we also document what may be the initial differentiation of the leaf ecomorph with larger, pubescent, and toothy leaves. The emergence of these ecomorphs thus appears to be driven by adaptation to subtly different climatic conditions in separate geographic regions, as opposed to parapatric differentiation along elevational gradients as suggested by Viburnum species distributions in other parts of the neotropics.
Caught in the Act: Incipient Speciation at the Southern limit of Viburnum in the Central Andes
(European Organization for Nuclear Research, 2023) Carlos A. Maya‐Lastra; Patrick W. Sweeney; Deren A. R. Eaton; Vania Torrez; Carla Maldonado; Malu I. Ore-Rengifo; Mónica Arakaki; Michael J. Donoghue; Erika J. Edwards
Repository for: Caught in the Act: Incipient Speciation at the Southern limit of Viburnum in the Central Andes In this repository, we are storing the following: HDF5 file of the assembly produced by ipyrad of our RADseq reads (bolivia_history.seqs.hdf5) HDF5 files with the SNPs found in item 1 (bolivia_history.snps.hdf5) Phylip file containing the final alignment used for the tree reconstruction (10-bolivia-initial_mcov0.25_rcov0.1_ALLscaff_SelectiveSampling.phy) For additional reproducibility material (scripts, notebooks) check: https://github.com/camayal/southern-oreinotinus
Cinchona anderssonii (Rubiaceae), a new overlooked species from Bolivia
(Q15088586, 2017) Carla Maldonado; Claes Persson; Joaquina Albán Castillo; Alexandre Antonelli; Nina Rønsted
Cinchona anderssonii, a new species from the Yungas forests of the Andes in Bolivia, is described and illustrated. It is unique in Cinchona by having the combination of elliptic leaf blades glossy above, distinct circular pit domatia at secondary vein axils, basipetally dehiscent capsules, and relatively large seeds (8–11 mm long). A taxonomic key for the identification of the Cinchona species occurring in Bolivia is presented.
Endemic Plant Species of Bolivia and Their Relationships with Vegetation
(IntechOpen, 2019) Mónica Moraes R.; Carla Maldonado; Freddy S. Zenteno-Ruíz
The inventory of Bolivia’s vascular plants lists 2402 endemic species (ca. 20% of 12,339 of native flora). Among angiosperms, there are 2263 species from 124 families and 641 genera, whereas among pteridophytes, there are 139 species from 16 families and 29 genera. Seven families with the greatest number of endemic species are Orchidaceae (418), Asteraceae (246), Bromeliaceae (147), Cactaceae (127), Poaceae (92), and Piperaceae (81). Cleistocactus and Puya have 14 and 55 endemic species, respectively, so representing 82.3 and 84.6% of the species in these genera. Bolivia’s endemic species show distribution patterns associated with past geological events, orographic dynamics (of the Andes and in the Cerrado), as well as areas of diversification. Dry xeric and humid regions host local and regional endemics in specific families and biogeographic regions of high conservation importance. Humid montane forests in the Yungas and dry inter-Andean valleys are rich in endemic species with 51 and 22% of the total recorded in the respective regions. Nevertheless, there are still many lesser known geographical areas that may generate new information in the short and medium term. Only 165 endemic species (6.9%) have been evaluated for their conservation status following IUCN categories with 49% assessed as endangered (EN).
Estimating species diversity and distribution in the era of <scp>B</scp>ig <scp>D</scp>ata: to what extent can we trust public databases?
(Wiley, 2015) Carla Maldonado; Carlos I. Molina; Alexander Zizka; Claes Persson; Charlotte M. Taylor; Joaquina Albán Castillo; Eder Chilquillo; Nina Rønsted; Alexandre Antonelli
Open databases and integrative bioinformatic tools allow a rapid approximation of large-scale patterns of biodiversity across space and altitudinal ranges. We found that geographic inaccuracy affects diversity patterns more than taxonomic uncertainties, often leading to false positives, i.e. overestimating species richness in relatively species poor regions. Public databases for species distribution are valuable and should be more explored, but under scrutiny and validation by taxonomic experts. We suggest that database managers implement easy ways of community feedback on data quality.
Estructura, composición y variabilidad del bosque subandino xérico en un sector del Valle del río Tuichi, Anmi Madidi, La Paz (Bolivia)
(2004) Alfredo Fuentes Claros; Alejandro Araujo Murakami; Héctor Cabrera Condarco; Freddy Canqui; Leslie Cayola; Carla Maldonado; Narel Paniagua
Se evaluaron 1.3 has. de bosque subandino xerico en el valle del Tuichi donde se midieron todas las lenosas con DAP > 2.5 cm en parcelas de 0.1 has. Se registraron 4709 tallos en total, con un promedio de 362.2± 132.3/0.1 ha. El promedio del area basal fue de 2.9± 1.1 m2/0.1 ha. Se encontraron 171 especies y 50 familias, con promedios de 48±7.5 especies y 24.8±3.8 familias por parcela. Las especies de mayor importancia ecologica (IVI) fueron Phyllostylon rhamnoides, Anadenanthera colubrina y Trichilia catigua; las familias con mayor IVIF fueron Fabaceae, Meliaceae y Ulmaceae. El Analisis de Componentes Principales diferencio dos grupos de parcelas o comunidades: una comunidad de cimas y laderas caracterizada por Zanthoxylum fagara, Astronium urundeuva y Erythrina amazonica; y otra comunidad de fondos de valle y terrazas caracterizada por Chrysophyllum gonocarpum, Randia armata y Gallesia integrifolia. Biogeograficamente predominan especies de bosques estacionalmente secos del arco pleistocenico, reforzando la teoria de la existencia durante el Pleistoceno de una formacion de bosques secos mucho mas extensa que la actual; le siguen en orden de importancia elementos de bosques humedos de tierras bajas y por ultimo elementos andinos que concentran los endemismos y caracterizan a esta formacion. Palabras claves: Bosque seco subandino Madidi, estructura, composicion, variabilidad, biogeografia. ABSTRACT We present detailed information on structure and floristic composition of the xeric subandean forest in a sector of the Tuichi valley, in the Madidi Natural Area of Integrated Management, La Paz-Bolivia. We evaluated 1.3 has. of forest where we measured all the woody plants with DBH > 2.5 cm, in plots of 0.1 ha. A total of 4709 stems with means of 362.2± 132.3/0.1 ha were recorded. The total basal area was of 37.7 m2 with means of 2.9±1.1 m2/0.1 ha (S.D.). We recorded 171 species in 50 families, with means of 48±7.5 species and 24.8±3.8 families per plot. The species of greatest ecological importance (IVI) were Phyllostylon rhamnoides, Anadenanthera colubrina and Trichilia catigua; the families with greatest IVIF were Fabaceae, Meliaceae and Ulmaceae. A Principal Component Analysis distinguished two groups of plots or plant communities: a community found on top and slopes of ridges characterized by Zanthoxylum fagara, Astronium urundeuva and Erythrina amazonica; and the other a community found in the valley bottoms and terraces was characterized by Chrysophyllum gonocarpum, Randia armata and Gallesia integrifolia. Biogeographycally predominates species of seasonally dry forests of the pleistocenic arc, reinforcing the theory of the existence during the Pleistocene of one formacion of dry forests much more extensive that in the present; they follow in importance order elements of humid lowland forests and finally Andean elements that concentrate the endemism and characterize this formation. Key words: Madidi subandean dry forest, structure, composition, variability, biogeography.
Functional traits mediate the effect of environmental conditions on tree growth of common Andean trees
(Elsevier BV, 2025) Eduardo Aguirre-Mazzi; Carla Maldonado; Leslie Cayola; Alfredo F. Fuentes; M. Isabel Loza; Christine E. Edwards; J. Sebastián Tello
Understanding how plant functional strategies interact with environmental variation is essential to predict the impacts of global change on forest communities. Here we investigated how resource-acquisition strategies, captured by branch and leaf traits, interact with environmental gradients, including climate, soil fertility, and solar radiation exposure, to influence relative growth rates (RGR) in 224 tree species from tropical montane forests in the Madidi region of the Bolivian Andes. Using data from 33 permanent forest plots and Bayesian hierarchical models, we found that the effects of environmental conditions on tree growth were modulated by species’ resource-acquisition strategies. Our findings reveal that acquisitive species, with higher specific leaf area (SLA), larger leaf size, and lower tissue density, performed better in cooler, drier, thermally variable, nutrient-rich sites with low solar radiation. In contrast, conservative species, characterized by stress-tolerant traits (higher tissue density and smaller leaves), grew better in nutrient-poor, high-radiation environments and tended to be less responsive to climatic gradients. Our analysis relied on two major PCA axes of functional trait covariation that captured distinct mechanistic pathways but aligned with survival-growth trade-off. Our results suggest that whole-plant allocation strategies, reflected by a leaf-area vs wood density trade-off may be more important than leaf-level traits (e.g., SLA) under closed canopies, highlighting the multidimensionality of trait-growth relationships. Our results underscore the role of trait–environment matching in shaping species performance and community assembly, and highlight the importance of trait-based approaches for forecasting forest responses to climate and land-use change. • Plant traits and environmental gradients interact to drive tree growth in the Andes. • Acquisitive species are more sensitive to climatic gradients than conservative ones. • Soil fertility favors acquisitive species whereas conservatives tolerate poor soils. • High solar exposure favors conservative species growth, limits acquisitive species. • Leaf area and wood density better predict growth compared to SLA in adult trees.
Historical chemical annotations of Cinchona bark collections are comparable to results from current day high-pressure liquid chromatography technologies
(Elsevier BV, 2019) Nataly Allasi Canales; Tobias Gress; Claus Cornett; Kim Walker; Felix Driver; Alexandre Antonelli; Carla Maldonado; Mark Nesbitt; Christopher J. Barnes; Nina Rønsted
How many Macropsychanthus (Leguminosae: Papilionoideae) species are found in Bolivia? Clarification of the taxa, a new species and an identification key
(Springer Science+Business Media, 2025) Andrés Fonseca‐Cortés; Cristiane Snak; Stephan Beck; R. P. Clark; Bente Klitgaard; Rosember Hurtado-Ulloa; Leslie Cayola Perez; Carla Maldonado; Luciano Paganucci de Queiroz
La importancia de las plantas medicinales, su taxonomía y la búsqueda de la cura a la enfermedad que causa el coronavirus (COVID-19)
(2020) Carla Maldonado; Narel Y. Paniagua-Zambrana; Rainer W. Bussmann; Freddy S. Zenteno-Ruíz; Alfredo F. Fuentes
MEDICIÓN DE LOS CAMBIOS MORFOLÓGICOS Y DE BIOMASA, Y DEL CONTENIDO DE ÁCIDO OXÁLICO, DESPUÉS DE IRRADIACIÓN IR Y UV EN OXALIS TRIANGULARIS
(2020) Ruth Nina; Carla Maldonado; Esther Valenzuela; Santiago Tarqui; Armando R Ticona-Bustillos; Flavio Ghezzi; Giovanna R. Almanza
El efecto que tiene la radiación solar sobre la morfología, biomasa y distintos compuestos químicos presentes en las plantas es de interés para la seguridad alimentaria frente al cambio climático. Este estudio tiene como objetivo contribuir al conocimiento del efecto de radiación infrarroja (IR) y ultravioleta (UV-A, UV-B) sobre la concentración de ácido oxálico, la biomasa y morfología en Oxalis triangularis (Oxalidaceae). Para esto, la especie fue expuesta a luz visible con radiación IR, UV-A o UV-B por separado y se estableció un grupo de control expuesto únicamente a luz visible. Cinco semanas después se contabilizó el número de hojas, se observaron los cambios morfológicos, se obtuvo el peso fresco y seco de las hojas y rizomas de cada espécimen, y la cuantificación de ácido oxálico se realizó por espectrofotometría UV/Visible. Los resultados mostraron que la biomasa, altura y número de hojas aumenta con la exposición a la radiación infrarroja, mientras que no se determinaron diferencias significativas en estos parámetros con la radiación UV-A. Con la radiación UV-B se observó despigmentación en los foliolos, un cierto brillo en los mismos por aumento probable de las ceras y una disminución en la altura del peciolo. Respecto a la concentración de ácido oxálico no se observaron diferencias significativas con los diferentes tratamientos, aunque se observa una tendencia a disminuir con IR y aumentar con UV-B. Estos hallazgos podrían tener implicaciones en plantas que contengan ácido oxálico por su valor nutricional, por esta razón se debe continuar con más estudios.
Phylogeny Predicts the Quantity of Antimalarial Alkaloids within the Iconic Yellow Cinchona Bark (Rubiaceae: Cinchona calisaya)
(Frontiers Media, 2017) Carla Maldonado; Christopher J. Barnes; Claus Cornett; Else Holmfred; Steen Honoré Hansen; Claes Persson; Alexandre Antonelli; Nina Rønsted
Considerable inter- and intraspecific variation with respect to the quantity and composition of plant natural products exists. The processes that drive this variation remain largely unknown. Understanding which factors determine chemical diversity has the potential to shed light on plant defenses against herbivores and diseases and accelerate drug discovery. For centuries, Cinchona alkaloids were the primary treatment of malaria. Using Cinchona calisaya as a model, we generated genetic profiles of leaf samples from four plastid (trnL-F, matK, rps16, and ndhF) and one nuclear (ITS) DNA regions from twenty-two C. calisaya stands sampled in the Yungas region of Bolivia. Climatic and soil parameters were characterized and bark samples were analyzed for content of the four major alkaloids using HPLC-UV to explore the utility of evolutionary history (phylogeny) in determining variation within species of these compounds under natural conditions. A significant phylogenetic signal was found for the content of two out of four major Cinchona alkaloids (quinine and cinchonidine) and their total content. Climatic parameters, primarily driven by changing altitude, predicted 20.2% of the overall alkaloid variation, and geographical separation accounted for a further 9.7%. A clade of high alkaloid producing trees was identified that spanned a narrow range of altitudes, from 1,100 to 1,350 m. However, climate expressed by altitude was not a significant driver when accounting for phylogeny, suggesting that the chemical diversity is primarily driven by phylogeny. Comparisons of the relative effects of both environmental and genetic variability in determining plant chemical diversity have scarcely been performed at the genotypic level. In this study we demonstrate there is an essential need to do so if the extensive genotypic variation in plant biochemistry is to be fully understood.
Radial growth decline in a tropical Andean treeline in Bolivia
(2025) Rose Oelkers; Laia Andreu‐Hayles; Rosanne D’Arrigo; Arturo Pacheco-Solana; Milagros Rodríguez‐Catón; M. Eugenia Ferrero; Ernesto Tejedor; A C.; Carla Maldonado; Daniel Ruíz
Abstract. Relative to research efforts in higher latitiudes, the impact of climate shifts in the tropical treeline remains understudied. Little is known about the tree growth dynamics and climate response at this treeline over the past few centuries, and at present under a rapidly changing environment. Here we provide information on recent changes in tree-ring patterns of Polylepis pepei BB.Simpson, a tropical tree species that grows in a monospecific forest at the elevational treeline in the Andes-Amazon ecotone of Bolivia and identify factors that limit its radial growth. We first developed a ring width (RW) chronology spanning 1867–2018 C.E. using dendrochronological methods and independently verified annual periodicity with radiocarbon dating. The RW chronology indicates a significant (p < 0.01) radial growth decline in P. pepei since 1997, a trend that mirrors a decrease reported in other Polylepis species from the drier central Andes of South America. P. pepei tree-ring width (RW) was mostly limited by mean, minimum, and maximum temperature and precipitation during austral summer (November–January). Over the instrumental period (1981–2019) prior-year temperatures negatively affected current-year tree growth (p < 0.05), while prior-year wet conditions were associated with higher growth (p < 0.05). Gridded temperature records (1901–2019) showed a significant increase in minimum temperatures and a decline in the diurnal temperature range since 1967, which may reduce orographic convection and water availability at higher elevations where our forest is located. In situ daily measurements from dataloggers in the forest recorded higher temperatures and lower relative humidity values when data was available. Our results suggest less moisture availability associated with warming conditions was related to the observed tree-growth decline. If temperature continues to rise at current rates, one of the highest-elevation tree species on the globe, P. pepei, could face severe consequences. This work provides insights into the past and historical trends of a tropical Andean treeline, which shows a recent decline also observed in other high-elevation forests (4657–4800 m.a.s.l.) of tropical South America (>17° S).
Radiocarbon and wood anatomy as complementary tools for generating tree-ring records in Bolivia
(Frontiers Media, 2023) Arturo Pacheco-Solana; Rose Oelkers; Rosanne D’Arrigo; Guaciara M. Santos; Milagros Rodríguez‐Catón; Ernesto Tejedor; Eugenia Ferrero; Alfredo F. Fuentes; Carla Maldonado; Laia Andreu‐Hayles
The science of tropical dendrochronology is now emerging in regions where tree-ring dating had previously not been considered possible. Here, we combine wood anatomical microsectioning techniques and radiocarbon analysis to produce the first tree-ring chronology with verified annual periodicity for a new dendrochronological species, Neltuma alba (commonly known as "algarrobo blanco") in the tropical Andes of Bolivia. First, we generated a preliminary chronology composed of six trees using traditional dendrochronological methods (i.e., cross-dating). We then measured the 14C content on nine selected tree rings from two samples and compared them with the Southern Hemisphere (SH) atmospheric 14C curves, covering the period of the bomb 14C peak. We find consistent offsets of 5 and 12 years, respectively, in the calendar dates initially assigned, indicating that several tree rings were missing in the sequence. In order to identify the tree-ring boundaries of the unidentified rings we investigated further by analyzing stem wood microsections to examine anatomical characteristics. These anatomical microsections revealed the presence of very narrow terminal parenchyma defining several tree-ring boundaries within the sapwood, which was not visible in sanded samples under a stereomicroscope. Such newly identified tree rings were consistent with the offsets shown by the radiocarbon analysis and allowed us to correct the calendar dates of the initial chronology. Additional radiocarbon measurements over a new batch of rings of the corrected dated samples resulted in a perfect match between the dendrochronological calendar years and the 14C dating, which is based on good agreement between the tree-ring 14C content and the SH 14C curves. Correlations with prior season precipitation and temperature reveal a strong legacy effect of climate conditions prior to the current Neltuma alba growing season. Overall, our study highlights much potential to complement traditional dendrochronology in tree species with challenging tree-ring boundaries with wood anatomical methods and 14C analyses. Taken together, these approaches confirm that Neltuma alba can be accurately dated and thereby used in climatic and ecological studies in tropical and subtropical South America.
Recent growth increase in endemic Juglans boliviana from the tropical Andes
(Elsevier BV, 2023) Rose Oelkers; Laia Andreu‐Hayles; Rosanne D’Arrigo; Arturo Pacheco-Solana; Milagros Rodríguez‐Catón; Alfredo Fuentes; Guaciara M. Santos; Ernesto Tejedor; M. Eugenia Ferrero; Carla Maldonado
The spatial coverage of tree-ring chronologies in tropical South America is low compared to the extratropics, particularly in remote regions. Tree-ring dating from such tropical sites is limited by the generally weak temperature seasonality, complex coloration, and indistinct anatomical morphology in some tree species. As a result, there is a need to complement traditional methods of dendrochronology with innovative and independent approaches. Here, we supplement traditional tree-ring methods via the use of radiocarbon analyses to detect partial missing rings and/or false rings, and wood anatomical techniques to precisely delineate tree-ring boundaries. In so doing we present and confirm the annual periodicity of the first tree-ring width (TRW) chronology spanning from 1814 to 2017 for Juglans boliviana (‘nogal’), a tree species growing in a mid-elevation tropical moist forest in northern Bolivia. We collected 25 core samples and 4 cross-sections from living and recently harvested canopy-dominant trees, respectively. The sampled trees were growing in the Madidi National Park and had a mean age of 115 years old, with certain trees growing for over 200 years. Comparison of (residual and standard) TRW chronologies to monthly climate variables shows significant negative relationships to prior year May-August maximum temperatures (r = −0.54, p < 0.05) and positive relationships to dry season May-October precipitation (r = 0.60, p < 0.05) before the current year growing season. Additionally, the radial growth of Juglans boliviana shows a significant positive trend since 1979. Our findings describe a new and promising tree species for dendrochronology due to its longevity and highlight interdisciplinary techniques that can be used to expand the current tree-ring network in Bolivia and the greater South American tropics.
RETO CIUDAD NATURALEZA LA PAZ: UNA EXPERIENCIA DE OBSERVACIÓN Y REGISTRO DE LA BIODIVERSIDAD URBANA
(2023) Cecilia Flores-Turdera; Robert B. Wallace; Álvaro Garitano‐Zavala; Carla Maldonado; Cynthya Jurado; Daniela Álvarez; Wilma Angulo; Guido Ayala; Isabel Gómez; Mayli Hayes
La ciencia ciudadana incentiva la participación de las personas en proyectos de investigación científica. Una de las iniciativas más conocidas es el concurso City Nature Challenge, dirigida a registrar la biodiversidad en las ciudades mediante la aplicación iNaturalist. La región metropolitana de La Paz, Bolivia, participó de este concurso en 2019 y 2022 con el nombre de Reto Ciudad Naturaleza, gracias al impulso de Wildlife Conservation Society (WCS) Bolivia, la Carrera de Biología y el Instituto de Ecología de la Universidad Mayor de San Andrés (UMSA), y el Museo Nacional de Historia Natural (MNHN), que conformaron un Comité Organizador. El objetivo fue fortalecer los vínculos de la población urbana con la naturaleza para generar datos sobre el conocimiento y conservación de la biodiversidad. Las actividades se basaron en la promoción y difusión del concurso, eventos de capacitación en el manejo de aplicación iNaturalist, registro fotográfico, identificación taxonómica y entrega de certificados a los participantes. En 2019, La Paz compitió con 158 ciudades y consiguió el octavo lugar en número de especies (3.005), el tercer lugar en número de participantes (1.500) y el segundo en número de observaciones (46.931). En 2022, participaron 447 ciudades. La Paz lideró en las tres categorías del concurso, con 137.345 observaciones, 5.320 especies y 4.296 participantes. Más allá de estos resultados, destaca el compromiso de la ciudadanía paceña con su biodiversidad, lo que repercute en un vínculo cada vez más estrecho entre la población urbana y su entorno natural.