Southwestern North America Research Articles

Evidence for a Paleogene boninitic arc following oceanic plateau-continent collision in the Western Cordillera of Colombia

The Caicedo Tuffs is a recently mapped Paleogene volcanic arc unit in the northern Andes, which provides insight into the magmatism of northwestern South America following its collision with the Caribbean-Colombian Oceanic Plateau (CCOP) in the latest Cretaceous. New regional geological mapping, igneous petrography, whole-rock and pyroxene geochemistry, and zircon U-Pb dating are provided for the northern sector of the eastern flank of the Western Cordillera of Colombia (Antioquia). These data reveal that the Caicedo Tuffs unit is predominantly composed of primary volcaniclastic deposits (tuff to breccia) that record mafic subaqueous volcanism and limited orogenic building shortly after collision of the CCOP. The geochemistry of these deposits includes major element characteristics and immobile trace element patterns that are typical of boninites. Zircons from these igneous rocks constrain a crystallization age of ca. 57 Ma, with meso-Proterozoic to Jurassic inherited zircons most likely reflecting continental recycling by turbidites in the subduction zone. The boninitic affinity of the Caicedo Tuffs and existing regional igneous and tectonic constraints can be explained by resuming of subduction and/or sinking of an older oceanic slab along northern South America following collision of the CCOP with South America. The boninitic, primary volcaniclastic deposits of the Caicedo Tuffs are crosscut by basaltic-gabbroic sills and dykes with oceanic plateau-like geochemical affinities, which lack evidence for hydrous melting and are compositionally similar to igneous rocks of the CCOP. These intrusions are interpreted to reflect decompression melting of plume-related mantle inherited during the collision of the CCOP with South America or slab detachment. The occurrence of oceanic plateau-like intrusions in a Paleocene volcanic arc casts doubt on the origin of other oceanic plateau sequences of the Western Cordillera, which are generally attributed to the Cretaceous CCOP. The Caicedo Tuffs is a unique boninite unit of which the detailed spatiotemporal extent and petrogenesis remain to be constrained, but that can provide valuable insight into tectono-magmatic processes during oceanic plateau-continent collision.

A short fragment of mitochondrial DNA for the taxonomic identification of blow flies (Diptera: Calliphoridae) in northwestern South America.

Blow flies are of medical, sanitary, veterinary, and forensic importance. Their accurate taxonomic identification is essential for their use in applied research. However, neotropical fauna has not been completely studied or described, and taxa identification without the required training is a difficult task. Additionally, the current morphological keys are not fitting to all extant taxa. Molecular-based approaches are widely used to overcome these issues, including the standard 5' COI barcode fragment (~650 base pairs [bp]) for identification at the species level. Here, a shorter sequence of 5' COI fragment (~342 bp) was assessed for the identification of 28 blow fly species inhabiting the northwest of South America. One tree-based (the generalized mixed Yule-coalescent-GMYC) and 3 distance-based approaches (automatic barcode gap discover - ABGD, the best close match - BCM, and the nearest neighbor - NN) analyses were performed. Noticeably, the amplification and sequencing of samples that had been preserved for up to 57 years were successful. The tree topology assigned 113 sequences to a specific taxon (70% effectiveness), while the distance approach assigned to 95 (59% effectiveness). The short fragment allowed the molecular identification of 19 species (60% of neotropical species except for the Lucilia species and Hemilucilia semidiaphana). According to these findings, the taxonomic and faunistic considerations of the blow fly fauna were provided. Overall, the short fragment approach constitutes an optimal species confirmation tool for the most common blow flies in northwestern South America.

Early evolution of the megadiverse subtribe Philonthina (Staphylinidae: Staphylininae: Staphylinini) and its Neotropical lineage

AbstractPhilonthina (2864 species in 74 genera) represents almost one‐half of the diversity of Staphylinini and is the largest of its subtribes. Most Philonthina species are found in tropical areas, but the origin of this diversity is still not well understood, mainly because their systematics belongs to a past era of taxonomy. Such is the case of a group of genera, most of them endemic to the Neotropical region (NT), whose monophyly has been repeatedly confirmed and which constitutes the so‐called Neotropical lineage (NL). However, basal relationships have not been clarified, neither for Philonthina nor its NL. The NL includes ∼300 species and 26 genera, but two of them (Belonuchus Nordmann and Paederomimus Sharp) account for two‐thirds of its species. Here, using the largest molecular‐based phylogeny of Philonthina and its NL to date, a time‐calibrated phylogeny, and ancestral range reconstructions for the NL, we explore the evolutionary history of Philonthina with a focus on its NL to reveal their early evolution and diversification in the NT. We show that Philonthina originated during the Late Cretaceous ∼ 67.6 Ma and diversified into five main lineages mostly during the Eocene. The NL originated in northwestern South America (SA) and the Andes not earlier than 64.2 Ma from a Laurasian lineage present in SA ∼49.1–69.9 Ma. Shortly afterward, that is, 39.9–56.9 Ma, the NL diversified into the Andean clade and the most species‐rich Belonuchus‐Paederomimus group. Our analyses recover northwestern SA and the Andes as the primary centers of diversification. Dispersal events to the northern landmasses took place at least three times during the Miocene in the early evolution of the NL.

Waves of Influence. Pacific Maritime Networks Connecting Mexico, Central America and Northwestern South America Waves of Influence. Pacific Maritime Networks Connecting Mexico, Central America and Northwestern South America , Dumbarton Oaks Pre-Columbian Symposia and Colloquia, edited by Christopher S. Beekman and Colin McEwan, Washington, D.C., USA, Harvard University Press, 2022, 616pp., 60 b&w photos, 205 colour photos, 90 b&w illustrations,

Waves of Influence. Pacific Maritime Networks Connecting Mexico, Central America and Northwestern South America <b>Waves of Influence. Pacific Maritime Networks Connecting Mexico, Central America and Northwestern South America</b> , Dumbarton Oaks Pre-Columbian Symposia and Colloquia, edited by Christopher S. Beekman and Colin McEwan, Washington, D.C., USA, Harvard University Press, 2022, 616pp., 60 b&amp;w photos, 205 colour photos, 90 b&amp;w illustrations,

Kinematics and Convergent Tectonics of the Northwestern South American Plate During the Cenozoic

AbstractThe interaction of the northern Nazca and southwestern Caribbean oceanic plates with northwestern South America (NWSA) and the collision of the Panama‐Choco arc (PCA) have significant implications on the evolution of the northern Andes. Based on a quantitative kinematic reconstruction of the Caribbean and Farallon/Farallon‐derived plates, we reconstructed the subducting geometries beneath NWSA and the PCA accretion to the continent. The persistent northeastward migration of the Caribbean plate relative to NWSA in Cenozoic time caused the continuous northward advance of the Farallon‐Caribbean plate boundary, which in turn resulted in its progressive concave trench bending against NWSA. The increasing complexity during the Paleogene included the onset of Caribbean shallow subduction, the PCA approaching the continent, and the forced shallow Farallon subduction that ended in the fragmentation of the Farallon Plate into the Nazca and Cocos plates and the Coiba and Malpelo microplates by the late Oligocene. The convergence tectonics after late Oligocene comprised the accretional process of the PCA to NWSA, which evolved from subduction erosion of the forearc to collisional tectonics by the middle Miocene, as well as changes of convergence angle and slab dip of the Farallon‐derived plates, and the attachment of the Coiba and Malpelo microplates to the Nazca plate around 9 Ma, resulting in a change of convergence directions. During the Pliocene, the Nazca slab broke at 5.5°N, shaping the modern configuration. Overall, the proposed reconstruction is supported by geophysical data and is well correlated with the magmatic and deformation history of the northern Andes.

Calcareous microfossil biostratigraphy of Upper Miocene to Pliocene deposits of the Sinú-San Jacinto Belt, Caribbean region of Colombia

A compilation of previous biostratigraphic studies conducted in Upper Miocene to Pliocene deposits from the Caribbean region of Colombia reveals a predominant reliance on mollusks and benthic foraminifera for age determinations, with planktonic microfossils being less explored. To contribute to this biostratigraphic background, we have performed biostratigraphic analyses of calcareous nannoplankton, an oceanic planktonic micropaleontological group, on 71 mudrock samples from two stratigraphic sections located in the Sinú-San Jacinto Belt (SSJB). The Canalete stratigraphic section, outcropping in the southwestern portion of the belt, yielded the biostratigraphic markers Discoaster bergenii, Discoaster berggrenii, Discoaster surculus, and Reticulofenestra pseudoumbilicus. This assemblage, typical of the Zone NN11, indicates that the 50-m-thick section was accumulated during the Late Miocene, sometime between the late Tortonian and late Messinian. The ANH-Conuco-1 well, a cored stratigraphic section drilled in the northeastern area of the belt, also contained the above-mentioned biostratigraphic markers as well as Amaurolithus primus-delicatus, Ceratolithus acutus, Discoaster quinqueramus, Helicosphaera sellii, and Reticulofenestra rotaria. These taxa suggest that the stratigraphic interval between 754.1 m and 58.4 m in this cored section is enclosed within the zones NN11 and NN12, ranging in age from Late Miocene to Early Pliocene (late Tortonian to earliest Zanclean). Reworked nannofossils Cyclicargolithus floridanus, Discoaster deflandrei, Sphenolithus disbelemnos, and Sphenolithus heteromorphus were observed in both localities, implying the redeposition of Lower to Middle Miocene and, possibly, Paleogene marine sediments. This is supported by previous documentation of reworked planktonic foraminifera in Upper Miocene to Pliocene deposits from the Caribbean region of Colombia. The identified calcareous nannoplankton assemblages not only provide additional constraints on the existing biostratigraphic data of planktonic foraminifera in this region, but also aid in the correlation of both analyzed stratigraphic sections with other Upper Miocene deposits in northwestern South America.

Orogenic gold belt overlap in the eastern Peninsular Ranges batholith: La Rumorosa mining area, Baja California, Mexico

Gold deposits in the La Rumorosa mining area (Baja California), located in the eastern Peninsular Ranges batholith (PRB), consist of auriferous quartz-(carbonate) veins hosted by brittle-ductile shear zones within metamorphic and synorogenic plutonic rocks. A combination of two geochronology methods, U–Pb zircon dating of country rocks and 40Ar/39Ar dating of hydrothermal and metamorphic white micas, along with the structural characterization of the main orebodies, has allowed the differentiation of two gold mineralization events in the study area. The oldest deposit (>93 Ma) is related to the main compressive phase of the PRB construction (∼110‒90 Ma) and is part of the yet poorly known Peninsular Ranges orogenic gold belt. Two other gold deposits were dated at ∼77 and 75 Ma, an age span that approximately corresponds to the beginning of the Laramide tectonism instead. Therefore, these deposits can be considered the oldest and westernmost constituents of the Caborca orogenic gold belt (∼69‒36 Ma), formerly recognized in the neighboring states of Sonora, Arizona, and the southeastern tip of California. Furthermore, the Laramide gold deposits at La Rumorosa are contemporaneous with the first generation (∼76‒74 Ma) of copper porphyries in the southern North American Cordillera belt, which are also situated on the opposite margin of the Gulf of California-San Andreas fault system. Both gold and copper deposits show an eastward migration during the early Upper Cretaceous, similar to the well-documented shift in magmatism and deformation in the region, albeit occurring asynchronously. The apparent continuous formation of orogenic gold deposits in southwestern North America from the middle Cretaceous to the Eocene, resulting from the strong convergence between the subducted Farallon plate and the continent, suggests a connection between the Peninsular Ranges and Caborca gold belts. We surmise that both of these orogenic gold belts may form part of a large metallogenic province in western Mexico.

Middle Miocene fire activity and C4 vegetation expansion in the Barstow Formation, California, USA

Abstract C4 grassland ecosystems expanded across North America between ca. 8 and 3 Ma. Studies of ungulate enamel and environmental indicators from the middle Miocene Barstow Formation of southern California (USA) have demonstrated the presence of C4 vegetation prior to the late Miocene expansion of C4 grasslands. Fire promotes the growth of modern C4 grasslands and may have contributed to the Miocene expansion of C4 vegetation. We analyzed the concentration and accumulation rate (CHAR) of microscopic charred particles from sediment samples spanning the Barstow Formation in order to investigate the relationship between fire activity, canopy cover, and the presence of C4 vegetation. Concentration and CHAR were low throughout the formation then increased dramatically at 13.5 Ma. Enriched values of δ13C from soil organic matter and phytolith counts indicate the presence of C4 grasses and seasonally dry, open-canopy habitats at this time. The spike in concentration coincides with climatic cooling and drying in southern California after the Miocene Climatic Optimum. Increased fire activity may have contributed to habitat opening from forest to woodland and promoted the spread of C4 plants. This is the first charcoal record of fire activity from the middle Miocene of southwestern North America.

Pliocene–Pleistocene hydrology and pluvial lake during Marine Isotope Stages 5a and 4, Deep Springs Valley, western Great Basin, Inyo County, California

AbstractDeep Springs Valley (DSV) is a hydrologically isolated valley between the White and Inyo mountains that is commonly excluded from regional paleohydrology and paleoclimatology. Previous studies showed that uplift of Deep Springs ridge (informal name) by the Deep Springs fault defeated streams crossing DSV and hydrologically isolated the valley sometime after eruption of the Pleistocene Bishop Tuff (0.772 Ma). Here, we present tephrochronology and clast counts that reaffirms interruption of the Pliocene–Pleistocene hydrology and formation of DSV during the Pleistocene. Paleontology and infrared stimulated luminescence (IRSL) dates indicate a freshwater lake inundated Deep Springs Valley from ca. 83–61 ka or during Late Pleistocene Marine Isotope Stages 5a (MIS 5a; ca. 82 ka peak) and 4 (MIS 4; ca. 71–57 ka). The age of pluvial Deep Springs Lake coincides with pluvial lakes in Owens Valley and Columbus Salt Marsh and documents greater effective precipitation in southwestern North America during MIS 5a and MIS 4. In addition, we hypothesize that Deep Springs Lake was a balanced-fill lake that overflowed into Eureka Valley via the Soldier Pass wind gap during MIS 5a and MIS 4. DSV hydrology has implications for dispersal and endemism of the Deep Springs black toad (Anaxyrus exsul).

Masticatory mechanisms, dental function, and diet in Triassic trilophosaurids (Reptilia: Allokotosauria)

Documenting evidence of feeding behavior in extinct vertebrates is crucial to understanding trophic structure and stability of ecosystems over periods of Earth's history. Direct evidence of trophic interactions in the fossil record is rare, but proxies like dental microwear enable testable hypotheses of feeding behavior in extinct taxa. Here we present new evidence on the masticatory apparatuses and feeding behaviors of Late Triassic (Norian) trilophosaurid reptiles from southwestern North America based on Scanning Electron Microscope (SEM) observation and quantitative analysis of dental microwear in isolated teeth and dentigerous elements. Trilophosaurids are a Late Triassic archosauromorph group known from Europe and North America with distinctive labiolingually expanded teeth that are usually tricuspid; this clade is hypothesized to be herbivorous based on qualitative comparisons of their dentition to those of living taxa. Our study is among the first to infer their diet within a quantitative comparative framework. Analysis of pit-to-scratch ratios (a proxy for the hardness/toughness of dietary intake) indicate dietary disparity between the three examined trilophosaurid taxa, possibly driven by differing plant preferences. Analysis of scratch orientations, caused by contact between opposite teeth during jaw closure (a proxy for the direction of masticatory movements), may suggest derivation of a masticatory mechanism including labiolingual movement in Trilophosaurus, differing from the orthal jaw closure mechanism ancestral to archosauromorphs that is likely conserved in the sister group to Trilophosauridae, the Azendohsauridae. Variance in dental microwear patterns between the sampled taxa suggests potential herbivore niche space partitioning amongst North American trilophosaurids during the Norian. Furthermore, microwear evidence for complex masticatory movement in trilophosaurids may suggest previously unknown craniomandibular specializations, highlighting the need for reexamination of trilophosaurid craniomandibular morphology and jaw closure mechanics.

Microevolutionary Processes in a Foundation Tree Inform Macrosystem Patterns of Community Biodiversity and Structure

Despite an increased focus on multiscale relationships and interdisciplinary integration, few macroecological studies consider the contribution of genetic-based processes to landscape-scale patterns. We test the hypothesis that tree genetics, climate, and geography jointly drive continental-scale patterns of community structure, using genome-wide SNP data from a broadly distributed foundation tree species (Populus fremontii S. Watson) and two dependent communities (leaf-modifying arthropods and fungal endophytes) spanning southwestern North America. Four key findings emerged: (1) Tree genetic structure was a significant predictor for both communities; however, the strength of influence was both scale- and community-dependent. (2) Tree genetics was the primary driver for endophytes, explaining 17% of variation in continental-scale community structure, whereas (3) climate was the strongest predictor of arthropod structure (24%). (4) Power to detect tree genotype—community phenotype associations changed with scale of genetic organization, increasing from individuals to populations to ecotypes, emphasizing the need to consider nonstationarity (i.e., changes in the effects of factors on ecological processes across scales) when inferring macrosystem properties. Our findings highlight the role of foundation tree species as drivers of macroscale community structure and provide macrosystems ecology with a theoretical framework for linking fine- and intermediate-scale genetic processes to landscape-scale patterns. Management of the genetic diversity harbored within foundation species is a critical consideration for conserving and sustaining regional biodiversity.

Prevalence and Molecular Characterisation of Blastocystis sp. Infecting Free-Ranging Primates in Colombia.

Infection with Blastocystis sp. has been reported in free-living and captive non-human primates (NHPs); however, surveys on Blastocystis sp. from north-western South America are scarce. This study aimed to identify Blastocystis sp. in free-ranging NHPs living in Colombia. A total of 212 faecal samples were collected from Ateles hybridus, Cebus versicolor, Alouatta seniculus, Aotus griseimembra, Sapajus apella, and Saimiri cassiquiarensis. Smears and flotation were used for morphological identification. For samples microscopically classified as positive for Blastocystis sp., we used conventional PCR to amplify and sequence two regions of the SSU rRNA gene and used Maximum Likelihood methods and Median Joining Network analyses for phylogenetic analyses. Via microscopy, 64 samples were Blastocystis sp. positive. Through molecular analyses, 18 sequences of Blastocystis sp. subtype 8 (ST8) were obtained. Strain and allele assignment together with a comparative phylogenetic approach confirmed that the sequences were ST8. Alleles 21, 156, and 157 were detected. Median Joining network analyses showed one highly frequent haplotype shared by specimens from Colombia and Peru and close relationships between haplotypes circulating in NHPs from Colombia, Ecuador, Brazil, and Mexico. This survey could support the elaboration of a more accurate epidemiological picture of the Blastocystis sp. infecting NHPs.

Isotope record of groundwater recharge mechanisms and climate change in southwestern North America

Understanding the response of groundwater systems to changes in climate is crucial at a time when human-caused climate change appears to be increasing in magnitude and rate. Groundwater preserves records of past effects resulting from climate change at the time-scale of late Pleistocene-Holocene climate evolution. Detailed regional datasets provide opportunities for evaluating past changes as a means of anticipating future climate-groundwater relations. Isotope parameters δ18O, δ2H and uncorrected 14C, considered together in large groundwater datasets from southwestern North America, provide evidence of changes in groundwater recharge mechanisms and the climate changes that led to them. The evidence consists in positive shifts in δ18O and δ2H in paleowater recharge related to a 13–15 ka shift recorded in in δ18O of speleothem deposits, and as concurrent changes in recharge seasonality in the core area of the North American monsoon. A negative shift in δ18O and δ2H, most likely contemporaneous with a regional 51–55 ka change speleothem deposits, is recorded in certain basins with deep, confined groundwater. A14C threshold of 10 percent modern carbon serves empirically to distinguish paleowaters before and after the 13–15 ka event. A younger, negative isotope shift has occurred in Baja California. The 13–15 ka shift is regional but is not recorded in all basins studied and appears to be absent at the northwestern and southeastern limits of the study area. Relations among the isotope parameters may be complicated by factors such as isotope altitude effects, delayed melting of Pleistocene ice, changing degrees of evaporation in river water and introduction of anthropogenic 14C. Recharge mechanisms fall into two patterns: (1) dominant winter recharge with varying degrees of evaporation prior to infiltration, and (2) recharge in both summer and winter, but only during the wettest months. Pattern (2) replaced pattern (1) at 13–15 ka in the core area of the North American monsoon. Later, the present-day pattern of recharge from summer-fall rain associated with tropical depressions replaced predominant winter recharge in southern and eastern Baja California. A post-1950 negative shift in δ18O and δ2H, observed in southern Nevada and northern New Mexico, may be of anthropogenic origin and related to development of large-scale irrigation in California.

Provenance of Carboniferous-Permian sedimentary units in southern Mexico: evidence for peri-arc basin evolution during the Pangea assembly

ABSTRACT The Oaxacan Complex Carboniferous-Permian sedimentary cover in southern México records provenance shifts through time, reflecting the collision between Gondwana and Laurentia to amalgamate Pangea. The integration of petrological analysis and LA-ICP-MS U-Pb zircon geochronology from Santiago, Ixtaltepec and Yododeñe formations compared with adjacent terranes suggests that: (1) during the Early Mississippian, the Santiago Formation received sediments mainly from local sources such as the Oaxacan Complex and Tiñu Formation, with minor contributions from adjacent peri-Gondwana sources. The magmatic activity may have started during this time (~359–346 Ma) (2) during the Late Mississippian (Ixtaltepec Formation), detrital zircon grains of Ediacaran-Cambrian age are dominant, derived from sediments either related to the Pan-African/Brasiliano orogeny or the opening of the Iapetus Ocean; (3) during the Late Mississippian-Middle Pennsylvanian, intercalated marine volcaniclastic sandstone (Ixtaltepec Formation) provides the first record of Carboniferous arc-related volcanism reported in southern Mexico, dated between 330 and 308 Ma; (4) the early Permian Yododeñe Formation records the exhumation and erosion of the sedimentary cover during the final stage of Pangea assembly. Rhyodacitic subvolcanic sills and lavas dated at ~282–270 Ma are present throughout the succession. Volcanism and ca. 360–308 Ma detrital zircon grains could be associated with a Carboniferous magmatic arc formed by subduction of the Rheic oceanic plate beneath Gondwana. Slightly younger detrital zircon and subvolcanic rocks dated at ~300–270 Ma are linked to a western Pangea arc developed in response to the subduction of the Paleo-Pacific Ocean following Pangea assembly. Our results suggest that the Carboniferous-Permian units were deposited in a peri-arc basin, sharing sediment provenance with the Maya and Coahuila blocks, the Sierra de Juárez Complex, and northwestern South America.

Phylogenomics of Aralia sect. Aralia (Araliaceae): Signals of hybridization and insights into its species delimitations and intercontinental biogeography

Genome-scale data have significantly increased the number of informative characters for phylogenetic analyses and recent studies have also revealed widespread phylogenomic discordance in many plant lineages. Aralia sect. Aralia is a small plant lineage (14 spp.) of the ginseng family Araliaceae with a disjunct distribution between eastern Asia (11 spp.) and North America (3 spp.). We herein employ sequences of hundreds of nuclear loci and the complete plastomes using targeted sequence capture and genome skimming to reconstruct the phylogenetic and biogeographic history of this section. We detected substantial conflicts among nuclear genes, yet different analytical strategies generated largely congruent topologies from the nuclear data. Significant cytonuclear discordance was detected, especially concerning the positions of the three North American species. The phylogenomic results support two intercontinental disjunctions: (1) Aralia californica of western North America is sister to the eastern Asian clade consisting of A. cordata and A. continentalis in the nuclear tree, and (2) the eastern North American A. racemosa forms a clade with A. bicrenata from southwestern North America, and the North American A. racemosa - A. bicrenata clade is then sister to the eastern Asian clade consisting of A. glabra (Japan), A. fargesii (C China), and A. apioides and A. atropurpurea (the Hengduan Mountains). Aralia cordata is supported to be disjunctly distributed in Japan, Taiwan, the Ulleung island of Korea, and in Central, Southwest and South China, and Aralia continentalis is redefined with a narrower distribution in Northeast China, eastern Russia and peninsular Korea.

Spatio-temporal assessment of Gridded precipitation products across topographic and climatic gradients in Colombia

Gridded precipitation products (GPPs) represent an alternative to and a complement to gauge-based observations of precipitation, improving the representation of spatio-temporal precipitation variability in regions with scarce gauge networks. However, GPPs' accuracy varies among products, temporal resolution, and regions, indicating the need for particular regional performance assessments. In this study, we evaluate the performance of eight state-of-the-art GPPs (CHIRPSv2, CMORPHv1, ERA5, ERA5-Land, IMERG, MSWEPv2.8, PERSIANN-CCS, and PERSIANN-CDR) over the steep topographic and climatic gradients of Colombia, in northwestern South America. We use a point-to-pixel comparison between ground-based observations from 1334 gauges with the corresponding grid cell of each GPP at 3-day, monthly, seasonal (DJF, MAM, JJA, SON), and annual scales over 2005–2014. Five categorical indices are used to assess the ability of each GPP to capture different 3-day precipitation intensity events correctly. The Kling-Gupta efficiency and its components are used to assess the GPPs' performance over Colombia and its five natural regions. Our results show that, at the 3-day scale, GPPs can correctly identify the occurrence of no-precipitation events (< 1 mm/day), but their capacity to classify precipitation events (≥ 1 mm/day) is low. The best performance is observed at the monthly scale, particularly at low elevation zones (0–1000 m.a.s.l), compared to 3-day and annual scales. Seasonally, GPPs tend to perform better during the dry season compared to the wet season in all regions. Overall, CHIRPSv2 outperforms other GPPs throughout the country and its five natural regions for all elevation zones and temporal scales, followed closely by MSWEPv2.8 and IMERG. PERSIANN-CCS and ERA5 products had the lowest performance, mainly over the driest and higher-altitude regions, respectively. This study provides insights into the performance of GPPs in complex climatic and topographic settings and, importantly, suggests the most suitable products for climate, hydrological, or ecological studies in a climatic, hydrological, and ecologically-strategic region.

Phylogenomics of trans-Andean tetras of the genus Hyphessobrycon Durbin 1908 (Stethaprioninae: Characidae) and colonization patterns of Middle America.

Hyphessobrycon is one of the most species rich and widely distributed genera in the family Characidae, with more than 160 species ranging from Veracruz, Mexico to Mar Chiquita Lagoon in Buenos Aires, Argentina. The majority of Hyphessobrycon diversity shows a cis-Andean distribution; only nine species are trans-Andean including H. compressus (Meek 1908). It is well established that Hyphessobrycon is not monophyletic but it has been suggested that natural groups can be identified within the larger Hyphessobrycon species group. In this study, we tested the monophyly of trans-Andean species of Hyphessobrycon and investigated the placement of H. compressus. We inferred the first phylogenomic hypothesis of trans-Andean Hyphessobrycon that includes nearly complete taxonomic sampling (eight of nine valid species) using ultraconserved elements (UCEs). We analyzed 75% (1682 UCEs), 90% (1258 UCEs), and 95% (838 UCEs) complete data matrices, and inferred phylogenomic hypotheses under concatenation and coalescent approaches. In all cases, we recovered the monophyly of trans-Andean Hyphessobrycon inclusive of H. compressus, strong support for three species groups, and evidence of cryptic diversity within the widespread H. compressus and H. condotensis. We used our phylogenomic hypothesis to investigate the biogeographic history of Hyphessobrycon in Middle America. Our ancestral range estimation analysis suggests a single event of cis- to trans-Andean colonization followed by stepwise colonization from the Pacific slope of northwestern South America (Chocó block) to northern Middle America (Maya block). Our work supports the recognition of the trans-Andean species as Hyphessobrycon sensu stricto and provides an evolutionary template to examine morphological characters that will allow us to better understand the diversity of Hyphessobrycon in Middle America.

Model Estimate of the Acidity of Atmospheric Precipitation Acidity Due to Anthropogenic Sulfur Compounds in the 20th Century

An analysis of the acidity of precipitation is carried out by using the ChAP-1.0 (Chemistry and Aerosol Processes) atmospheric sulfur cycle scheme developed for Earth System Models of Intermediate Complexity (EMICs)These calculations are forced by monthly mean anthropogenic emissions of sulfur dioxide to the atmosphere in 1850–2000 adapted from the CMIP5 (Coupled Models Intercomparison Project, phase 5) database and by long-term means (taking into account annual variations) of meteorological variables adapted from the ERA-Interim reanalysis for 1979–2015. It was revealed that significant acidity of precipitation (minimum pH of hydrometeors) is typical for regions with high anthropogenic loading of sulfur compounds in atmosphere – Europe, southeast Asia, east North America, southern Africa, and western South America. In these regions in the last decades of the 20th century, typical precipitation values of pH amount from 2.5 to 3.5, which agrees well with the available measurements. The maximum acidity of precipitation (the minimum pH of hydrometeors, which is close to 2) due to anthropogenic sulfur are noted in the eastern Mediterranean region. Atmospheric transport leads to regions with pH 3.5 covering almost all of Eurasia in the last decades of the 20th century. The influence of this transport is also noticeable in other midlatitudinal regions – south of North America and western South America. In general, the ChAP scheme can be used in EMICs, but after a refinement to account for the effect of various types of precipitation on the wet deposition of sulfur compounds from the atmosphere and the effects of orography on the transport of chemical species in the atmosphere

Shamans in the Colonial Frontier Zone: Spirit Mastery in Eighteenth-Century Coastal Ecuador

Abstract The aim of this article is to advance our knowledge of past shamanic practices in northwestern South America through an analysis of colonial-era criminal cases of people accused of using “superstitious” healing practices. A reading of three cases from late eighteenth-century Ecuador (the colonial Audiencia of Quito) reveals details of the techniques that these healers were using. Shamans attempted to control spirits through various means, including battles, esoteric chants, and the use of tobacco, alcohol, stones, and the fangs of predatory animals. The records indicate that on Ecuador’s coast, healers practiced a type of frontier-zone shamanism in which people of different ethnoracial and cultural backgrounds engaged in shamanic practices. The research expands existing studies of the historical exchanges of shamanic knowledge, practices, and sacred objects in colonial and modern frontier zones by contributing with a regional focus on the Pacific coast of Ecuador.

Groundwater depletion in California’s Central Valley accelerates during megadrought

Groundwater provides nearly half of irrigation water supply, and it enables resilience during drought, but in many regions of the world, it remains poorly, if at all managed. In heavily agricultural regions like California’s Central Valley, where groundwater management is being slowly implemented over a 27-year period that began in 2015, groundwater provides two–thirds or more of irrigation water during drought, which has led to falling water tables, drying wells, subsiding land, and its long-term disappearance. Here we use nearly two decades of observations from NASA’s GRACE satellite missions and show that the rate of groundwater depletion in the Central Valley has been accelerating since 2003 (1.86 km3/yr, 1961–2021; 2.41 km3/yr, 2003–2021; 8.58 km3/yr, 2019–2021), a period of megadrought in southwestern North America. Results suggest the need for expedited implementation of groundwater management in the Central Valley to ensure its availability during the increasingly intense droughts of the future.