Northwest Peru Research Articles

Tectono‐Stratigraphic Insights on the Dynamics of a Complex Subduction Zone, Northern Peruvian Forearc

AbstractTwo main types of subduction are recognized around the world: accretionary and erosive. The northern Peruvian margin is a well‐known example of a margin subjected to subduction erosion, but to date the along‐margin variability and temporal changes in subduction process and forearc basin evolution have not been characterized in detail. Interpretation of regional seismic lines and integration of oil‐industry wells and seafloor data captures the erosive nature of subduction underneath the forearc with only a minor accretionary component to the north. Episodes of uplift driven by plate coupling were followed by normal faulting/extensional collapse due to plate decoupling. This mechanism explains the dominance of normal faulting across the forearc until the Oligocene with a slight reactivation within the Miocene. The subduction history is complex and includes a reduction in plate convergence rate related to forearc crustal shortening, represented by large‐scale structures including the Peru fault (reactivated) and the Illescas fault‐propagation anticlines of the Northwest Peru transpressional system. This crustal deformation started in the Miocene. Integration with magnetic anomaly data indicates that activity of the present‐day transpressional system driven by tectonic escape of the Nazca Sliver toward the northeast, may explain the seismicity gap in southern Ecuador and northern Peru. An evolutionary model of the northern Peruvian margin shows how subduction zone geodynamics left its erosive fingerprint in the forearc basin configuration.

Spatial transferability of an agent-based model to simulate Taenia solium control interventions

BackgroundModels can be used to study and predict the impact of interventions aimed at controlling the spread of infectious agents, such as Taenia solium, a zoonotic parasite whose larval stage causes epilepsy and economic loss in many rural areas of the developing nations. To enhance the credibility of model estimates, calibration against observed data is necessary. However, this process may lead to a paradoxical dependence of model parameters on location-specific data, thus limiting the model’s geographic transferability.MethodsIn this study, we adopted a non-local model calibration approach to assess whether it can improve the spatial transferability of CystiAgent, our agent-based model of local-scale T. solium transmission. The calibration dataset for CystiAgent consisted of cross-sectional data on human taeniasis, pig cysticercosis and pig serology collected in eight villages in Northwest Peru. After calibration, the model was transferred to a second group of 21 destination villages in the same area without recalibrating its parameters. Model outputs were compared to pig serology data collected over a period of 2 years in the destination villages during a trial of T. solium control interventions, based on mass and spatially targeted human and pig treatments.ResultsConsidering the uncertainties associated with empirical data, the model produced simulated pre-intervention pig seroprevalences that were successfully validated against data collected in 81% of destination villages. Furthermore, the model outputs were able to reproduce validated pig seroincidence values in 76% of destination villages when compared to the data obtained after the interventions. The results demonstrate that the CystiAgent model, when calibrated using a non-local approach, can be successfully transferred without requiring additional calibration.ConclusionsThis feature allows the model to simulate both baseline pre-intervention transmission conditions and the outcomes of control interventions across villages that form geographically homogeneous regions, providing a basis for developing large-scale models representing T. solium transmission at a regional level.Graphical

Another Recently Recognized Monotypic Genus Is No Longer Monotypic: A Second Species of Pachycaulos (Gesneriaceae) from the Huancabamba Depression in Northern Peru

Abstract— A new species is described from the Huancabamba Pass, a relict montane forest in northwest Peru, near the southwestern border of Ecuador. Pachycaulos huancabambae J.L.Clark & Moonlight is a terrestrial or lithophytic herb with scandent stems that grows in dense mats of bryophytes. This is the second species of Pachycaulos and renders that taxon as non-monotypic. We discuss several other genera of Gesneriaceae that are also no longer monotypic because of recent exploratory research in tropical forests and increased taxon sampling from ongoing phylogenetic studies. A molecular phylogenetic analysis based on nrDNA ITS is presented that strongly supports the monophyly and sister-group relationship of P. huancabambae and P. nummularia. Based on IUCN guidelines, a preliminary conservation status is assigned as Critically Endangered (CR).

Multicriteria Analysis in Apiculture: A Sustainable Tool for Rural Development in Communities and Conservation Areas of Northwest Peru

Apiculture plays a vital role in maintaining a genetically diverse ecosystem and is an economic activity that contributes to the development of rural communities, thereby enhancing the livelihoods of beekeepers. However, despite the presence of over forty thousand beekeepers in Peru, there is currently no cartographic information available on optimal areas for the development of apiculture. Our study focused on assessing the suitability of land for apiculture development in rural and indigenous communities within the Amazonas Department in northwest Peru. We integrated biophysical and socioeconomic criteria using the Multiple Criteria Evaluation (MCE) technique, in conjunction with state-of-the-art geoinformation and earth observation techniques, to model and validate land suitability for supporting apiculture. It was identified that suitability is influenced by biophysical criteria (65%) and socioeconomic criteria (35%), resulting in highly suitable areas covering 315.6 km2 within the territory of peasant communities, 128.4 km2 within native communities, and an additional 41.4 km2 within conserved areas. Furthermore, to validate our results, we combined the use of high-resolution satellite imagery and visits to artisanal producers. This research provides valuable insights for spatiotemporal land use planning, emphasizing apicultural activity as a driver of rural development and biodiversity conservation. Consequently, this study contributes as a management tool to promote apicultural activities as support for rural development and in local-level decision making.

Ticks registered in the Biosphere Reserve of Northwest Peru

Ticks primarily affect livestock and have the potential to transmit disease. The objective of the research was to record the georeferencing, distribution and identification of the species present in three Protected Natural Areas (ANP) that are part of the Biosphere Reserve of Northwest Peru (RBNO). The collection was carried out in five representative places of each ANP, due to the difficulty of finding fauna within the ANP, a convenience sampling was used for animals, and a random sampling was used for plants, using transects through the places where domestic animals’ transit. and wild and ranchers. The collected specimens were labeled to have distribution and identification in each of the sampled places. Dale's keys were used for genus level identification and Álvarez's keys were used for preliminary identification of species. Four specimens were collected in the Cerros de Amotape National Park, 55 in the Angolo Hunting Reserve and 271 in the Tumbes National Reserve. Seven species were recorded: Amblyoma cajennense, A. dissimile, A. maculatum and A. testudinis; Rhipicephalus (Boophilus) microplus and R. sanguineus and an unidentified species of the genus Haemaphysalis.

Phylogenetic relationships and systematics of the bamboo‐specialist Amaurospiza blue seedeaters

The Amaurospiza ‘seedeaters’ are bamboo‐specialized mixed strategists, most often found in bamboos in vegetative state, feeding on buds, shoots, petioles and insects. As bamboos die after flowering, birds may wander in search of live vegetative bamboo. The three currently recognized species of Amaurospiza are allopatrically distributed: the Blackish‐blue Seedeater Amaurospiza moesta in the Atlantic Forest of Argentina, Brazil and Paraguay, and in forest enclaves in the Cerrado; the recently described Carrizal Seedeater Amaurospiza carrizalensis known from a few localities in southeastern Venezuela; and the Blue Seedeater Amaurospiza concolor distributed patchily from Mexico to Peru. Three subspecies are recognized within A. concolor: relicta in southwest Mexico, concolor from southern Mexico to Panama and aequatorialis from southwest Colombia to northwest Peru. Full species status has been advocated for relicta and aequatorialis but evidence supporting their recognition is weak, while relicta was described in the monospecific genus Amaurospizopsis. Here we (1) test the monophyly of Amaurospiza, (2) reconstruct the phylogenetic relationships of all its constituent taxa using mitochondrial and nuclear markers, (3) re‐assess species limits in Amaurospiza with the aid of vocalizations and genetic and plumage data, and (4) discuss the link between bamboo life history, biogeographical patterns and extent of genetic differentiation. Amaurospiza was found to be monophyletic in both the ND2 and multilocus analyses. In the ND2 tree A. moesta and A. carrizalensis were sister to each other, A. concolor was found to be paraphyletic because aequatorialis was placed as sister to moesta–carrizalensis, and a clade including nominate concolor and relicta was sister to all the other taxa. The multilocus tree showed the same relationships, but lacked nuclear samples of relicta. Mean ND2 pairwise distance between concolor and aequatorialis (8.3%) was greater than that between moesta and carrizalensis (5.7%), while relicta diverged on average 1.0% from nominate concolor. The South American clade has more slender bills and white underwing coverts, while the Central American clade has thicker bills and bluish underwing coverts. All taxa exhibited typical Amaurospiza songs with quickly delivered, warbled, pure and fairly high‐pitched musical notes. Number of inflections/second exhibited a stepped pattern, with concolor and relicta on the lower end and carrizalensis, aequatorialis and moesta on the upper end. Similarly, moesta, carrizalensis and aequatorialis had overall more inflections per note than concolor and relicta. Linear discriminant analysis using nine acoustic variables correctly assigned all 62 songs to the correct taxon. Morphology, plumage, vocalizations and phylogenetic data indicate that aequatorialis should be afforded full species status as the Ecuadorian Seedeater (A. aequatorialis), suggest keeping relicta as a subspecies of A. concolor and support continued recognition of A. carrizalensis. Our data support merging Amaurospizopsis into Amaurospiza.

Non-local validated parametrization of an agent-based model of local-scale Taenia solium transmission in North-West Peru.

The pork tapeworm, Taenia solium, is the cause of a preventable zoonotic disease, cysticercosis, affecting both pigs and humans. Continued endemic transmission of T. solium is a major contributor of epilepsy and other neurologic morbidity, and the source of important economic losses, in many rural areas of developing countries. Simulation modelling can play an important role in aiding the design and evaluation of strategies to control or even eliminate transmission of the parasite. In this paper, we present a new agent based model of local-scale T. solium transmission and a new, non-local, approach to the model calibration to fit model outputs to observed human taeniasis and pig cysticercosis prevalence simultaneously for several endemic villages. The model fully describes all relevant aspects of T. solium transmission, including the processes of pig and human infection, the spatial distribution of human and pig populations, the production of pork for human consumption, and the movement of humans and pigs in and out in several endemic villages of the northwest of Peru. Despite the high level of uncertainty associated with the empirical measurements of epidemiological data associated with T. solium, the non-local calibrated model parametrization reproduces the observed prevalences with an acceptable precision. It does so not only for the villages used to calibrate the model, but also for villages not included in the calibration process. This important finding demonstrates that the model, including its calibrated parametrization, can be successfully transferred within an endemic region. This will enable future studies to inform the design and optimization of T. solium control interventions in villages where the calibration may be prevented by the limited amount of empirical data, expanding the possible applications to a wider range of settings compared to previous models.

Underestimated Neotropical diversity: Integrative taxonomy reveals two unrelated look-alike species in a suboscine bird (Pachyramphus albogriseus)

Abstract We applied an integrative taxonomic framework to evaluate the systematics of the Neotropical Black-and-white Becard (Pachyramphus albogriseusSclater 1857). Combining phylogenomic (ultraconserved elements), morphological, and vocalization data, we confirmed that this species is polyphyletic; some individuals form a clade sister to P. polychopterus and should be afforded species rank as P. salviniRichmond 1899 (Slender-billed Becard), whereas the remaining subspecies of P. albogriseus (Broad-banded Becard) are sister to P. major. We found that P. salvini differs from P. albogriseus in song, color of the lores, wing-bar width, body size, and bill width. Whereas P. albogriseus occurs in montane forest in Costa Rica and Panama (ssp. ornatus) and along the eastern slope of the Andes from northern Venezuela to southern Peru (ssp. albogriseus), P. salvini is found in the lowlands from Pacific Colombia south to northwest Peru and in the Río Marañón drainage. The latter also occurs, possibly only seasonally, along the eastern slope of the Andes, where the two species’ ranges approach closely. We treat P. a. guayaquilensisZimmer 1936 as a junior synonym of P. salviniRichmond 1899, and P. a. coronatusPhelps and Phelps 1953 as a junior synonym of P. a. albogriseusSclater 1857. This study provides a striking example of a major problem for comparative biology: underestimated and mischaracterized diversity. We argue that there are likely many more cases like this awaiting discovery.

Rainy season precipitation forecasts in coastal Peru from the North American Multi‐Model Ensemble

AbstractWe assessed operational forecasts of rainy season (January–March [JFM]) precipitation over coastal Peru from seven global climate models (GCMs) in the North American Multi‐Model Ensemble (NMME) from 1982 to 2020. Similar to previous representations by GCMs, regional climate models, and atmospheric reanalyses, the NMME models produce excessive precipitation (more than twice the observed values) over all of coastal Peru. Based on a set of commonly used metrics (correlation, mean error, RMSE, and Heidke skill score), there is a wide range in accuracy among the NMME models. As expected, forecast accuracy degrades with increasing lead time from December to July, but the rate of decline varies greatly by region and among models. The cause(s) of differences in model performance remains unclear, but resolution does not appear to be a significant factor. Highest forecast skill is found for southwestern Peru (correlations with observations are significant at all lead times), probably because of its stronger relationship between rainfall and El Niño–Southern Oscillation (ENSO), and lowest skill occurs for west‐central Peru (insignificant correlations at all lead times). The distribution of interannual rainy season precipitation in northwestern Peru is extremely positively skewed (skewness >2), making evaluation of forecasts difficult from only a few years that deviate strongly from the mean. Improved correlations with observations across regions are generally found by subsetting multi‐model mean forecasts using the better‐performing models. Over northwest Peru at short lead times, NMME rainy season precipitation forecasts outperform a simple statistical correlation between JFM rainfall and ENSO, but not at longer leads, while NMME's forecasts for west‐central Peru underperform statistical correlations at all lead times. Over southwest Peru, the NMME models are consistently more skilful than a statistical correlation, and these differences become larger with increasing lead time.

Threatened Andean bears are negatively affected by human disturbance and free-ranging cattle in a protected area in northwest Peru

Threatened Andean bears are negatively affected by human disturbance and free-ranging cattle in a protected area in northwest Peru

<p><strong>A new species of <em>Clinanthus </em>(Amaryllidaceae: Amaryllidoideae: Clinantheae) from Cordillera de los Tarros, Northwest Peru, and notes on related species</strong></p>

Clinanthus longissimus B. Esquerre & Meerow sp. nov. is described from the Department of Cajamarca in northwest Peru. This new species has affinity with C. coccineus (Ruiz. & Pav.) Meerow, C. incarnatus (Kunth) Meerow and C. variegatus (Ruiz & Pav.) Meerow, from which it can be distinguished mainly by the length of the flower, the continuous floral tube without protuberances, the size of the staminal cup and the color of the tepals. C. longissimus is so far known only from the Province of Cutervo.

UNA NUEVA ESPECIE DE PASSIFLORA SECCIÓN DECALOBA (PASSIFLORACEAE) DE PERÚ

A new species of Passiflora Section Decaloba, P. andicola, endemic in northwest Peru is here described and illustrated. This new herbaceous climber differs from its related species in the indumentum, flower morphology and geographical distribution. Passiflora andicola inhabits montane forests of Cajamarca and Lambayeque Departments. In addition, the morphology and distributional range of P. andicola and related species are compared and discussed.

Adsorption of As(V), Cd(II) and Pb(II), in Multicomponent Aqueous Systems using Activated Carbons.

This paper studies the use of two activated carbon samples made of cocoa pod husk (CPH-AC) and one commercial activated carbon sample in the adsorption of As(V), Cd(II) and Pb(II) from multicomponent synthetic solutions and from the Puyango-Tumbes River water, a river located in northwest Peru. The characterization of the activated carbon samples was conducted. The CPH-AC samples exhibited a specific surface area (SBET) between 709 and 1117 m2/g and a pH point of zero charge (pHPZC) between 4.4 ± 0.2 and 5 ± 0.2, while the commercial material gave an SBET value of 775 m2/g and a pHPZC value of 7.6 ± 0.1. All the evaluated samples displayed the capacity to adsorb As(V), Cd(II) and Pb(II) from both aqueous systems. The adsorption efficiency for Pb was outstanding reaching the value of 89%. A pseudo-second order kinetic model was satisfactorily applied for most of the activated carbon samples.

Potential distribution, absolute density, and population size of Gray-backed Hawks (Pseudastur occidentalis) in a protected area in northwest Peru

Estimates of density and population size are fundamental in assessing population trends and ultimately in informing conservation management. Although the abundance of raptors is often expressed as indices of relative abundance, these can be poor correlates of absolute density. In 2008–2009, I calculated the absolute density and population size of Gray-backed Hawks (Pseudastur occidentalis), an endangered species and Tumbesian endemic, using line transect counts in four different habitat types in a protected area in northwestern Peru. The absolute density of Gray-backed Hawks in northwest Peru was estimated to be 0.65 individuals km−2, and the most suitable habitat for the species was located in the provinces of Manabí, Guayas, and Santa Elena in Ecuador, and Tumbes and Piura departments in Peru. The population of Gray-backed Hawks in my study areas in Tumbes was estimated to be 136, with 94% occurring in dry deciduous and deciduous forest. Because ∼60% of all detections in my study were made outside strictly protected areas, including the recently created Angostura-Faical Regional Conservation Area, conservation of the remaining, non-protected forests patches in Peru and Ecuador should be a high priority. The current global population of Gray-backed Hawks has been estimated to be between 250 and 999 birds and declining due to ongoing habitat destruction and fragmentation. Small populations in small habitat fragments, like those in my study area, have high conservation potential, provided that populations are not isolated, and hence should be the focus of constant monitoring. Distribución potencial, densidad absoluta y tamaño poblacional de Pseudastur occidentalis en un área protegida en el noroeste de Perú Estimaciones de la densidad y el tamaño poblacional son fundamentales para determinar tendencias poblacionales y para informar las decisiones de manejo para la conservación. A pesar que la abundancia de rapaces es comúnmente expresada como indicies de abundancia relativa, estos pueden estar poco relacionados con la densidad absoluta. En 2008–2009, calcule la densidad absoluta y tamaño poblacional de Pseudastur occidentalis, una especie en peligro y endémica de la región de Tumbes, utilizando conteos mediante transectos lineales, en cuatro tipos de hábitat, en un área protegida del noroeste de Perú. El estimado de la densidad absoluta de Pseudastur occidentalis en el noroeste de Perú fue de 0.65 individuos km2 y el hábitat mas adecuado para la especie esta ubicado en las provincias de Manabí, Guayas y Santa Elena en Ecuador y los departamentos de Tumbes y Piura en Perú. La población estimada de Pseudastur occidentalis en mis áreas de estudio en Tumbes fue de 136 individuos, con el 94% ocurriendo en bosque seco deciduo y bosque deciduo. Debido a que ∼60% de todas las detecciones en mi estudio se realizaron fuera de áreas estrictamente protegidas, incluyendo el Área de Conservación Regional Angostura-Faical, la cual fue creada recientemente, los parches de bosque no protegidos en Perú y Ecuador deben ser considerados como altamente prioritarios. La estimación población actual de Pseudastur occidentalis oscila entre 250 y 999 aves y disminuyendo debido a la continua destrucción de hábitat y su fragmentación. Las poblaciones pequeñas en fragmentos de hábitats pequeños como los de mi área de estudio, tienen un alto potencial para la conservación, siempre y cuando las poblaciones no se encuentren aisladas, y por lo tanto deberían ser el centro de monitoreo constate.

Andean Forearc Dynamics, As Recorded By Detrital Zircon From the Eocene Talara Basin, Northwest Peru

Research Article| June 01, 2015 Andean Forearc Dynamics, As Recorded By Detrital Zircon From the Eocene Talara Basin, Northwest Peru Angela M. Hessler; Angela M. Hessler 1The Deep Time Institute, 8711 Bluegrass Drive, Austin, Texas 78759, U.S.A. e-mail: ahessler@deeptimeinstitute.org Search for other works by this author on: GSW Google Scholar Andrea Fildani Andrea Fildani 2Statoil Research, Development and Innovation Center, 6300 Bridge Point Parkway, Suite 2–500 Austin, Texas 78730, U.S.A. Search for other works by this author on: GSW Google Scholar Journal of Sedimentary Research (2015) 85 (6): 646–659. https://doi.org/10.2110/jsr.2015.45 Article history received: 07 Oct 2014 accepted: 24 Mar 2015 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Angela M. Hessler, Andrea Fildani; Andean Forearc Dynamics, As Recorded By Detrital Zircon From the Eocene Talara Basin, Northwest Peru. Journal of Sedimentary Research 2015;; 85 (6): 646–659. doi: https://doi.org/10.2110/jsr.2015.45 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Sedimentary Research Search Advanced Search Abstract: Eocene strata of the Talara forearc basin of northwest Peru contain detrital-zircon (DZ) populations that, when integrated with other provenance indicators, record paleogeographic shifts in the Andean forearc that can be linked to larger-scale tectonic drivers such as subduction erosion, plate convergence rate, and regional accretion events. Because forearc basins along the western margin of South America are particularly difficult to preserve, the new DZ results provide rare insight into the trench–arc dynamics associated with the Andean orogenic cycle. The Talara basin tapped into both the Andean volcanic arc and older basement, and the DZ populations subsequently reflect long-lived plate interactions and progressive crustal growth along the northwestern edge of Amazonia, Gondwana, and South America. Dominant U–Pb zircon age populations include: 36–110 Ma (Andes convergence); 215–285 Ma (western Gondwana extension); 460–625 Ma (Rodinia extension and western Gondwana convergence); 950–1250 Ma (Grenville orogeny); and > 1250 Ma (Amazonia assembly). The data corroborate previous geochronology on pre-Andean basement and support the existence of a Famatinian arc (∼ 480 Ma) and Carboniferous–Triassic magmatism along northwestern Gondwana. Pre-Andean and Amazonian DZ likely was recycled from Paleozoic metasedimentary rocks of the Andean Cordillera and Amotape terrane, although the data do not preclude delivery of Amazonian detritus directly into the forearc via a large-scale, westward drainage. The Andean DZ population constrains the timing of arc activity and quiescence, with two peaks at ∼ 75 Ma and ∼ 50 Ma, and a gap at ∼ 70 Ma, linked to accretion of the Caribbean Oceanic Plateau against northwest South America. Arc volcanism was concurrent with Eocene forearc deposition, and syndepositional DZ is used to revise maximum depositional age for the upper Eocene Helico Member and Verdun Formation. Progressive subsidence and arc shut-down in the late Eocene coincide with arc collision to the north, uplift of the Amotape block, subduction erosion, and slab shallowing. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Habitat Associations Within a Raptor Community in a Protected Area in Northwest Peru

Knowledge of the habitat characteristics that influence the distribution of raptors in the neotropics is vital for their conservation. I used logistic regressions (General Linear Models; GLM) to model habitat distribution for eleven raptor species occurring in the Cerros de Amotape National Park, the Tumbes National Reserve, and surrounding areas in northwestern Peru. Between May and December 2008 and 2009, raptors were surveyed along transects, and associated habitat data collected in 70 randomly allocated 1-km2 plots. Ten habitat variables were selected for modelling. Spatial autocorrelation in the distribution of species was measured through Moran's I and later habitat models were ranked using Akaike's Information Criterion corrected for small sample sizes (AICc). The most important variables that influenced the presence of species included the percentage of vegetation cover at different strata and elevation. The presence of the tree species, ceibo (Ceiba trichistrandra) and guasima (Guazuma ulmifolia), were also important. The percentage of vegetation cover from 5–15 m appeared in all models for Turkey Vulture (Cathartes aura), Crane Hawk (Geranospiza caerulescens), Great Black Hawk (Buteogallus urubitinga), and Harris's Hawk (Parabuteo unicinctus). These findings suggest that vertical structure of forested areas is of particular importance for raptors at the study site, including those of conservation concern. I recommend that forested areas north of the Cerros de Amotape National Park and close to Ecuador should be protected.

Novel mutations on the ace-1 gene of the malaria vector Anopheles albimanus provide evidence for balancing selection in an area of high insecticide resistance in Peru.

BackgroundResistance to multiple classes of insecticides has been detected in the malaria vector Anopheles albimanus in northwest Peru. Acetylcholinesterase (AChE) insensitivity has previously been associated with resistance to organophosphate (OP) and carbamate (CA) insecticides in arthropods. A single point mutation on the ace-1 gene (G119S) associated with resistance to OPs and CAs has been described previously in four anopheline species, but not in field-collected An. albimanus. The present study aimed to characterize the role of ace-1 in conferring resistance to both OPs and CAs in the An. albimanus population in Tumbes, Peru.MethodsThe frequency and intensity of resistance to OPs and CAs was quantified through bioassays of female An. albimanus collected between 2012 and 2014, and the presence of insensitive AChE was confirmed using biochemical assays. A portion of the ace-1 gene flanking codon 119 was amplified and sequenced from individuals used in the bioassays and biochemical assays, as well as from historical samples collected in 2008. Statistical analyses were conducted to determine: (1) associations between genotype and AChE insensitivity; and, (2) associations between genotype and resistance phenotype.ResultsAfter confirming high levels of resistance to fenitrothion, malathion, and bendiocarb through bioassays, two novel polymorphisms were identified at the first and second loci of codon 119, with all individuals from the 2012–2014 collections being heterozygous at the first base (G/T) and either heterozygous (G/C) or homozygous mutants (C/C) at the second base. Based on sequence data from historical samples, these mutations arose prior to 2008, but became fixed in the population between 2008 and 2012. Homozygotes at the second locus had significantly higher levels of AChE insensitivity than heterozygotes (p <0.05). Individuals phenotypically susceptible to OPs and CAs were more likely to be heterozygous at the second locus (p <0.01). Cloning identified four individuals each containing three distinct genotypes, suggesting that a duplication of the ace-1 gene may have occurred.ConclusionsThe occurrence of heterozygotes at two loci and the presence of three genotypes in four individuals suggest that balancing selection could be maintaining OP and CA resistance in this population, while minimizing associated fitness costs.

Effects of plant–soil feedback on tree seedling growth under arid conditions

Aims Plants are able to influence their growing environment by changing biotic and abiotic soil conditions. These soil conditions in turn can influence plant growth conditions, which is called plant–soil feedback. Plant–soil feedback is known to be operative in a wide variety of ecosystems ranging from temperate grasslands to tropical rain forests. However, little is known about how it operates in arid environments. We examined the role of plant–soil feedbacks on tree seedling growth in relation to water availability as occurring in arid ecosystems along the west coast of South America. Methods In a two-phased greenhouse experiment, we compared plant–soil feedback effects under three water levels (no water, 10% gravimetric moisture and 15% gravimetric moisture). We used sterilized soil inoculated with soil collected from northwest Peru (Prosopis pallida forests) and from two sites in north-central Chile (Prosopis chilensis forest and scrublands without P. chilensis). Important Findings Plant–soil feedbacks differed between plant species and soil origins, but water availability did not influence the feedback effects. Plant–soil feedbacks differed in direction and strength in the three soil origins studied. Plant–soil feedbacks of plants grown in Peruvian forest soil were negative for leaf biomass and positive for root length. In contrast, feedbacks were neutral for plants growing in Chilean scrubland soil and positive for leaf biomass for those growing in Chilean forest soil. Our results show that under arid conditions, effects of plant–soil feedback depend upon context. Moreover, the results suggest that plant–soil feedback can influence trade-offs between root growth and leaf biomass investment and as such that feedback interactions between plants and soil biota can make plants either more tolerant or vulnerable to droughts. Based on dissecting plant–soil feedbacks into aboveground and belowground tissue responses, we conclude that plant–soil feedback can enhance plant colonization in some arid ecosystems by promoting root growth.

Trench‐forearc interactions reflected in the sedimentary fill of Talara basin, northwest Peru

ABSTRACTExceptional exposure of the forearc region of NW Peru offers insight into evolving convergent margins. The sedimentary fill of the Talara basin spans the Cretaceous to the Eocene for an overall thickness of 9000 m and records within its stratigraphy the complicated history of plate interactions, subduction tectonics, terrane accretion, and Andean orogeny. By the early Tertiary, extensional tectonism was forming a complex horst and graben system that partitioned the basin into a series of localized depocentres. Eocene strata record temporal transitions from deltaic and fluvial to deep‐water depositional environments as a response to abrupt, tectonically controlled relative sea‐level changes across those depocentres. Stratigraphic and provenance data suggest a direct relationship between sedimentary packaging and regional tectonics, marked by changes in source terranes at major unconformities. A sharp shift is recognized at the onset of deepwater (bathyal) sedimentation of the Talara Formation, whose sediments reflect an increased influx of mafic material to the basin, likely related to the arc region. Although the modern topography of the Amotape Mountains partially isolates the Talara basin from the Lancones basin and the Andean Cordillera to the east, provenance data suggest that the Amotape Mountains were not always an obstacle for Cordilleran sediment dispersal. The mountain belt intermittently isolated the Talara basin from Andean‐related sediment throughout the early Tertiary, allowing arc‐related sediment to reach the basin only during periods of subsidence in the forearc region, probably related to plate rearrangement and/or seamounts colliding with the trench. Intraplate coupling and/or partial locking of subduction plates could be among the major causes behind shifts from contraction to extension (and enhanced subduction erosion) in the forearc region. Eventually, collisional tectonic and terrane accretion along the Ecuadorian margin forced a major late‐Eocene change in sediment dispersal.

Tectonic evolution and paleogeography of the Mesozoic Pucará Basin, central Peru

The Pucará Basin of Peru is an elongate trough that subsided landward of a NNW-trending structural high during the Late Triassic–Early Jurassic. It formed as a postrift regional sag as the earlier Triassic fault-controlled Mitu rifts yoked together. The rift and transitional postrift basins were associated with a NW-striking sinistral shear zone that controlled isopachs and facies distributions and resulted in magmatism and mineralization along its trend. A distinct association of later dolomitization and MVT lead–zinc mineralization also occurs with these basin-forming shear zones. Although basaltic and andesitic extrusives are common, there is no evidence that the Pacific margin was a magmatic arc until the upper Pucará, and then only weakly developed in northern Peru. Except in the upper Pucará of northwest Peru, geochemical studies, including whole rock and trace element analyses, indicate that intercalations of volcanic material have intraplate rift affinities. The basin fill has a three-part stratigraphic subdivision, comprising lower and upper carbonate platforms with an intermediate phase of basin overdeepening and sediment starvation that resulted in a regional, organic-rich argillaceous drape. Stratigraphic accumulation was dominated by axial patterns of onlap and progradation, though facies characteristics show it was augmented by periodic flooding of the western basin margin high. Marine invertebrate fossils indicate normal marine salinities. The sedimentological interpretation is based on a SW–NE transect in the southern part of the Pucará Basin. The Chambará (Norian–Rhaetian) and Condorsinga (Toarcian) formations were constructed principally by shallow-water carbonate sedimentation in lagoon-like subtidal, intertidal, and supratidal paleoenvironments. The subtidal carbonate platform is dominated by oolitic grainstones with subordinate bioclastic packstones. Subordinate open-basin facies in the Chambará Formation consist principally of crinoidal packstones and bioclastic wackestones. In the intertidal and supratidal facies, evaporite pseudomorphs are common and generally associated with algal mats and widespread early diagenetic dolomitization. During the Chambará and Condorsinga, subsidence typically was balanced by carbonate production and shallow-water environments prevailed; the basin had the characteristics of an overfilled basin. Conversely, the intermediate late Rhaetian–Sinemurian stage of basin subsidence was marked by underfilled deep water conditions. This widespread transgressive inundation of the Pucará Basin, recorded in the argillaceous Aramachay stratigraphy, correlates with similar events in other Andean basins.