Agricultural University of Ecuador

www.uagraria.edu.ec
Guayaquil, Ecuador
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Carranza J.,São Paulo State University | Carranza J.,University of Cordoba, Spain | Carranza J.,Agricultural University of Ecuador | Roldan M.,São Paulo State University | And 2 more authors.
Mammalian Biology | Year: 2017

Brocket deer Mazama nemorivaga and M. gouazoubira occur at the Amazon basin and southern areas, respectively, in parapatric distribution ranges. Both species can interbreed in captivity, although hybrids have serious fertility problems. Therefore, we expect natural selection to favour behavioural barriers against interspecific mating. We carried out no-choice tests with individuals of both species in captivity, along with white-tailed deer (Odocoileous virginianus) as outgroup. Behaviours were video recorded and analysed by using Generalized Mixed models, with interacting females and males as random subjects. Trials never led to copulation when the white-tailed-deer male was involved. Copulations within brocket deer species were more likely to occur when the individuals belonged to the same species (82.4%) but they also occurred quite frequently in interspecific interactions (35.7%). We identified some courtship behaviours, in males and females, which associated with a higher copulation probability or showed differences in frequency when performed to partners of the same or different species. In conclusion, our results reveal that the occurrence of facilitating behaviours and copulations were more common in intraspecific interactions, evidencing discrimination between species, but also that the precopulatory barrier was not strong between both brocket deer species. © 2017 Deutsche Gesellschaft für Säugetierkunde


Fiallo-Olive E.,University of Malaga | Chirinos D.T.,University of Zulia | Chirinos D.T.,Agricultural University of Ecuador | Geraud-Pouey F.,University of Zulia | Navas-Castillo J.,University of Malaga
Archives of Virology | Year: 2017

Wild plants of the family Convolvulaceae are hosts for a few New World begomoviruses (genus Begomovirus, family Geminiviridae). In this work, we report the complete genome sequence of a new begomovirus infecting the wild convolvulaceous plant Jacquemontia tamnifolia in Venezuela. The cloned bipartite genome showed the organization of typical New World begomoviruses and was found to be phylogenetically related to those of begomoviruses from Venezuela and other Caribbean countries. Several recombination events have been shown to have occurred involving genome fragment exchange with related begomoviruses infecting crops such as tomato and cucurbits and wild plants, including Jacquemontia sp. We propose the name jacquemontia yellow vein virus (JacYVV) for this new begomovirus. © 2017, Springer-Verlag Wien.


Lagos-Ortiz K.,Agricultural University of Ecuador | Medina-Moreira J.,Agricultural University of Ecuador | Salavarria-Melo J.O.,Agricultural University of Ecuador | Paredes-Valverde M.A.,University of Murcia | Valencia-Garcia R.,University of Murcia
Advances in Intelligent Systems and Computing | Year: 2018

It is extremely important that farmers regularly monitor their crop looking for symptoms that may reveal the presence of diseases. However, sometimes farmers have no access to information that helps them to respond to questions such as: what is wrong with their crop? and what can they do to deal with the problem? This situation could cause them to lose their crops, which in turn represents economic losses. Nowadays, there are solutions focused on the automatic diagnosis of diseases, including human diseases and diseases of specific crops such as maize. However, there is a lack of solutions focused on the diagnosis of diseases of short-cycle and perennial crops. In this sense, we propose an ontology-based solution for helping farmers to diagnose disease of such kind of crops from a set of symptoms perceived by farmers. For this purpose, our solution implements a rule-based engine that can diagnose a disease from the symptoms provided. The ontology and rule-based engine were designed in conjunction with a group of experts in plant pathology. Our proposal was evaluated in conjunction with farmers from the Costa Region of Ecuador achieving encouraging results. © Springer International Publishing AG 2018.


Blandon-Diaz J.U.,National University of Agriculture at Nicaragua | Blandon-Diaz J.U.,Swedish University of Agricultural Sciences | Forbes G.A.,International Potato Center | Andrade-Piedra J.L.,CIP | Yuen J.E.,Agricultural University of Ecuador
Plant Disease | Year: 2011

In this study, the adequacy of the late blight simulation model LATEBLIGHT (version LB2004) was evaluated under Nicaraguan conditions. During 2007 to 2008, five field experiments were conducted in three potato-production regions in northern Nicaragua. Two susceptible ('Cal White' and 'Granola') and one resistant ('Jacqueline Lee') potato cultivars were evaluated without use of fungicides and with three application intervals (4, 7, and 14 days) of the fungicide chlorothalonil. The simulation model was considered adequate because it accurately predicted high disease severity in susceptible cultivars without fungicide protection, and demonstrated a decrease in the disease progress curves with additional fungicide applications, similar to that observed in the plots. The model also generally predicted inadequate fungicide control, even with a 4-day spray interval, which also occurred in the field. Lack of adequate fungicide protection would indicate the need for cultivars with higher levels of durable resistance, and that farmers should consider more effective fungicides applications (higher dosages or different chemistries) if susceptible cultivars are used. © 2011 The American Phytopathological Society.


PubMed | Oklahoma State University and Agricultural University of Ecuador
Type: | Journal: Journal of virological methods | Year: 2016

Rose rosette disease is a disorder associated with infection by Rose rosette virus (RRV), a pathogen of roses that causes devastating effects on most garden cultivated varieties, and the wild invasive rose especially Rosa multiflora. Reliable and sensitive detection of this disease in early phases is needed to implement proper control measures. This study assesses a single primer-set based detection method for RRV and demonstrates its application in three different chemistries: Endpoint RT-PCR, TaqMan-quantitative RT-PCR (RT-qPCR) and SYBR Green RT-qPCR with High Resolution Melting analyses. A primer set (RRV2F/2R) was designed from consensus sequences of the nucleocapsid protein gene p3 located in the RNA 3 region of RRV. The specificity of primer set RRV2F/2R was validated in silico against published GenBank sequences and in-vitro against infected plant samples and an exclusivity panel of near-neighbor and other viruses that commonly infect Rosa spp. The developed assay is sensitive with a detection limit of 1fg from infected plant tissue. Thirty rose samples from 8 different states of the United States were tested using the developed methods. The developed methods are sensitive and reliable, and can be used by diagnostic laboratories for routine testing and disease management decisions.


Mora J.R.,Agricultural University of Ecuador | Mora J.R.,Venezuelan Institute for Scientific Research | Lezama J.,University of the East Venezuela | Cordova-Sintjago T.C.,University of Florida | Chuchani G.,Venezuelan Institute for Scientific Research
Molecular Physics | Year: 2015

The mechanisms of the gas-phase thermal decomposition of bicyclo[2.2.1]heptadiene and 3,7,7-trimethylbicyclo[2.2.1]hept-2-ene were examined by density functional theory calculations with the hybrid functionals: B3LYP, CAM-B3LYP, MPW1PW91, and PBEPBE. Reasonable agreements were found between theoretical and experimental values with the B3LYP hybrid functional. Three molecular concerted pathways for bicyclo[2.2.1]heptadiene decomposition are proposed. The retro-Diels-Alder (retro-DA) pathway yields cyclopentadiene and acetylene through a nearly synchronous transition state structure (Sy=0.97). The other two reaction channels are stepwisewith a common step with the formation of the intermediate bicyclo[4.1.0] heptadiene. This reaction is dominated by C-C bond breaking leading to the methylene migration by an early transition state in the reaction coordinate (Sy = 0.91). The rearrangements of the latter intermediate producing toluene were also studied. The retro-DA elimination of 3,7,7-trimethylbicyclo[2.2.1]hept-2-ene gives 1,5,5-trimethyl-cyclopenta-1,3-diene in a less synchronous process (Sy = 0.77). This fact may be due to the electronic effects of the methyl substituent. The latter product is unstable and undergoes methyl migrations to give a more stable isomer 1,2,3-trimethylcyclopenta-1,3-diene. The stepwise mechanism for the retro-DA reaction through a biradical intermediate appears to be unfavourable because the barrier is bigger than that for the concerted reaction. © 2015 Taylor & Francis.


Aguirre W.E.,DePaul University | Shervette V.R.,University of South Carolina | Navarrete R.,Agricultural University of Ecuador | Calle P.,ESPOL Polytechnic University | Agorastos S.,State University of New York at Stony Brook
Copeia | Year: 2013

Little is known about the freshwater fishes of western Ecuador despite serious environmental threats, including the creation of large artificial impoundments Phenotypic and genetic divergence of populations of a large predatory fish, Hoplias microlepis, is examined in rivers and artificial impoundments of the Guayas River drainage in western Ecuador Despite the recent formation of the impoundments (∼20 years prior to the sampling), H microlepis in these habitats diverged morphologically from river populations Impoundment fish tended to have larger eyes, longer dorsal and caudal fins, and thinner bodies than river fish Classification rates for habitat of origin based on morphometric measures were relatively high (71.7-83.3%), and the magnitude of morphological divergence was substantial when contrasted with divergence from H malabaricus, a congener from eastern Ecuador Frequencies of mtDNA d-loop haplotypes differed significantly among samples Genetic divergence between river samples implies that the genetic structure in the drainage predates the formation of the impoundments The genetic analysis also indicates that the morphological divergence between fish in different habitat types is not likely due to shared ancestry Genetic diversity tended to be higher in the river samples, and the percentage of private alleles was higher in the impoundment populations, which is consistent with rapid population expansion from a limited number of founders in impoundments © 2013 by the American Society of Ichthyologists and Herpetologists.


Mora J.R.,Agricultural University of Ecuador | Mora J.R.,Venezuelan Institute for Scientific Research | Lezama J.,University of the East Venezuela | Cordova-Sintjago T.C.,Florida College | Chuchani G.,Venezuelan Institute for Scientific Research
Molecular Physics | Year: 2015

The mechanisms of the gas-phase thermal decomposition of bicyclo[2.2.1]heptadiene and 3,7,7-trimethylbicyclo[2.2.1]hept-2-ene were examined by density functional theory calculations with the hybrid functionals: B3LYP, CAM-B3LYP, MPW1PW91, and PBEPBE. Reasonable agreements were found between theoretical and experimental values with the B3LYP hybrid functional. Three molecular concerted pathways for bicyclo[2.2.1]heptadiene decomposition are proposed. The retro-Diels–Alder (retro-DA) pathway yields cyclopentadiene and acetylene through a nearly synchronous transition state structure (Sy = 0.97). The other two reaction channels are stepwise with a common step with the formation of the intermediate bicyclo[4.1.0] heptadiene. This reaction is dominated by C–C bond breaking leading to the methylene migration by an early transition state in the reaction coordinate (Sy = 0.91). The rearrangements of the latter intermediate producing toluene were also studied. The retro-DA elimination of 3,7,7-trimethylbicyclo[2.2.1]hept-2-ene gives 1,5,5-trimethyl-cyclopenta-1,3-diene in a less synchronous process (Sy = 0.77). This fact may be due to the electronic effects of the methyl substituent. The latter product is unstable and undergoes methyl migrations to give a more stable isomer 1,2,3-trimethylcyclopenta-1,3-diene. The stepwise mechanism for the retro-DA reaction through a biradical intermediate appears to be unfavourable because the barrier is bigger than that for the concerted reaction. © 2015 Taylor & Francis


Gonzalez de Leon S.,Institute Ecologia Ac | Herrera I.,Agricultural University of Ecuador | Herrera I.,Venezuelan Institute for Scientific Research | Guevara R.,Institute Ecologia Ac
Ecology and Evolution | Year: 2016

Ecological invasions are a major issue worldwide, where successful invasion depends on traits that facilitate dispersion, establishment, and population growth. The nonnative succulent plant Kalanchoe pinnata, reported as invasive in some countries, is widespread in remnants of seasonally dry tropical forest on a volcanic outcrop with high conservation value in east-central Mexico where we assessed its mating system and demographic growth and identified management strategies. To understand its local mating system, we conducted hand-pollination treatments, germination, and survival experiments. Based on the experimental data, we constructed a life-stage population matrix, identified the key traits for population growth, weighted the contributions of vegetative and sexual reproduction, and evaluated management scenarios. Hand-pollination treatments had slight effects on fruit and seed setting, as well as on germination. With natural pollination treatment, the successful germination of seeds from only 2/39 fruit suggests occasional effective natural cross-pollination. The ratios of the metrics for self- and cross-pollinated flowers suggest that K. pinnata is partially self-compatible. Most of the pollinated flowers developed into fruit, but the seed germination and seedling survival rates were low. Thus, vegetative propagation and juvenile survival are the main drivers of population growth. Simulations of a virtual K. pinnata population suggest that an intense and sustained weeding campaign will reduce the population within at least 10 years. Synthesis and applications. The study population is partially self-compatible, but sexual reproduction by K. pinnata is limited at the study site, and population growth is supported by vegetative propagation and juvenile survival. Demographic modeling provides key insights and realistic forecasts on invasion process and therefore is useful to design management strategies. © 2016 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.


Herrera I.,Venezuelan Institute for Scientific Research | Herrera I.,Agricultural University of Ecuador | Ferrer-Paris J.R.,Venezuelan Institute for Scientific Research | Hernandez-Rosas J.I.,Agricultural University of Ecuador | And 2 more authors.
Journal of Arid Environments | Year: 2016

Kalanchoe daigremontiana and Stapelia gigantea are two succulent invasive species with potential impacts on recruitment of native vegetation in a protected area of importance for conservation of arid environments in northern South America. We hypothesized that while K. daigremontiana has the potential for inhibiting recruitment of native plants through allelopathic effects, S. gigantea could facilitate recruitment of nurse-dependent native taxa. To explore these contrasting impacts, we designed a comparative study and a transplant experiment. Density of native seedlings and species richness were significantly lower in patches invaded by K. daigremontiana when compared to patches with native vegetation or invaded by S. gigantea, suggesting that native-seedling recruitment is negatively affected by K. daigremontiana and not affected or facilitated by S. gigantea. The experiment did not generate results concordant with those obtained in the comparative study. Seedlings' recruitment of two selected native species was facilitated by presence of nurse-plants (exotics and natives); however, the magnitude of this effect varied according to the type of nurse-plant, susceptibility to herbivory, and herbivory level. We identify K. daigremontiana as the invasive with top need for management actions, because it has the potential to alter composition and physiognomy of native-plant communities in tropical arid environments. © 2016 Elsevier Ltd.

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