28 research outputs found
March of the Green Iguana : Non-native Distribution and Predicted Geographic Range of Iguana iguana in the Greater Caribbean Region
Green Iguanas (Iguana iguana L. 1758) have been introduced outside their native range largely through the pet trade. In many places, exotic populations have invaded and many have become established. Of special concern is the Greater Caribbean Basin, where several exotic populations of Green Iguanas have had a negative impact, and may threaten the conservation of several native species, including possible native and distinct forms of I. iguana in the Lesser Antilles, and the endangered Lesser Antilles Iguana (I. delicatissima Laurenti 1768). We assessed the risk of spread and invasion by Green Iguanas in the Greater Caribbean Basin using the maximum entropy niche-modeling algorithm (MaxEnt) to predict the potential distribution of this reptile. We used a total of 187 location points that represented occurrences from both the native and the invasive range, coupled with environmental data as predictor variables. Our model had average training and test AUC values of 0.90 and 0.87 respectively, indicating a high predictive ability. The model predicts suitable conditions for I. iguana in south and central Florida (mainly along the coast), and in regions of all the islands in the Caribbean. Given the known negative impact of Green Iguanas and their dispersal capabilities, governments in the Greater Caribbean Basin should manage non-native populations to prevent further spread, and revise and enact laws that allow management agencies to respond quickly in the case of new Green Iguana incursions
From the cage to the wild: introductions of Psittaciformes to Puerto Rico
Introduced psittacine birds can become highly invasive. In this study, we assessed invasions of Psittaciformes in Puerto Rico. We reviewed the literature, public databases, citizen science records, and performed in situ population surveys across the island to determine the historical and current status and distribution of psittacine species. We used count data from Ebird to determine population trends. For species whose populations were increasing, we modelled their potential distribution using niche modeling techniques. We found 46 Psittaciformes in Puerto Rico, of which 26% are only present as pets, at least 29 species have been reported in the wild, and of those, there is evidence that at least 12 species are breeding. Our results indicate that most introduced species which have been detected as established still persist, although mostly in localized areas and small populations. Clear evidence of invasiveness was found for Brotogeris versicolurus and Myiopsitta monachus, which have greatly expanded their range in recent years. Psittacara erythrogenys and Eupsittacula canicularis also showed population increases, although to a lesser degree. The niche models predicted suitable areas for the four species, and also indicate the potential for range expansion. We discuss the factors leading to invasion success, assess the potential impacts, and we discuss possible management strategies and research prospects
Habilidades prácticas y competencias digitales: perspectivas en la enseñanza
The main objective is to analyze how digital competencies impact the quality of theoretical-practical teaching and student learning. To achieve this, a bibliographic review was carried out that addressed relevant studies on teaching digital competencies in Latin American educational environments. This literature review approach made it possible to identify trends, challenges and opportunities in the integration of digital competencies in higher education, providing a comprehensive view of the importance of these competencies for the continuous improvement of teaching and learning in the region. Furthermore, the need to understand how these competencies relate to the constant evolution of technology and the changing demands of the labor market is highlighted. Likewise, the importance of providing adequate training to teachers is emphasized so that they can adapt effectively to digital environments and maximize the learning potential of students. In this sense, it is suggested that future research delve into the specific impact of these competencies in various educational contexts and consider practical strategies for their effective implementation. This holistic approach will contribute to further strengthening higher education in Latin America and preparing students for the challenges of the 21st century.El objetivo principal es analizar cómo las digitales competencias impactan en la calidad de la enseñanza teórico-práctica y el aprendizaje de los estudiantes. Para lograrlo, se llevó a cabo una revisión bibliográfica que abordó estudios relevantes sobre competencias digitales docentes en entornos educativos latinoamericanos. Este enfoque de revisión bibliográfica permitió identificar tendencias, desafíos y oportunidades en la integración de competencias digitales en la educación superior, proporcionando una visión integral de la importancia de estas competencias para la mejora continua de la enseñanza y el aprendizaje en la región. Además, se destaca la necesidad de comprender cómo estas competencias se relacionan con la evolución constante de la tecnología y las demandas cambiantes del mercado laboral. Asimismo, se enfatiza la importancia de proporcionar una formación adecuada a los docentes para que puedan adaptarse eficazmente a los entornos digitales y maximizar el potencial de aprendizaje de los estudiantes. En este sentido, se sugiere que futuras investigaciones profundicen en el impacto específico de estas competencias en diversos contextos educativos y consideren estrategias prácticas para su implementación efectiva. Este enfoque holístico contribuirá a fortalecer aún más la educación superior en América Latina y a preparar a los estudiantes para los desafíos del siglo XXI
INDUCCIÓN DE LA OVULACIÓN EN LLAMASMEDIANTE LA ADMINISTRACIÓN INTRAMUSCULAR DEL PLASMA SEMINAL DE LLAMA, ALPACAY TORO
Se seleccionaron 64 llamas hembras sin cría al pie y en condiciones reproductivas óptimas. El criterio de selección se basó en la presencia de un folículo dominante ³7mm, detectado por ecografía transrectal.Alas hembras seleccionadas se les aplicó 5mg deLH (LutropinV) para realizar una sincronización de la emergencia de una nueva onda folicular, confirmándose 12 días después la presencia de un nuevo folículo dominante (³7 mm). Los animales fueron entonces distribuidos al azar en cuatro grupos. Alos primeros tres grupos se les inyectó 2 ml vía i.m. de plasma seminal de llama, alpaca y toro, y al cuarto grupo (control) se le aplicó PBS (suero básico fosfatado). La ocurrencia de ovulación se evaluó dos días después, encontrándose que las tratadas con plasma seminal de llamas y alpacas tuvieron una tasa de ovulación del 100%, las tratadas con plasma seminal de toro de 25% y ninguna en el grupo control. Al noveno día post tratamiento se midió el tamaño del cuerpo lúteo, encontrándose que no existe diferencia significativa entre los grupos tratados. En base a los resultados se puede señalar que la administración intramuscular de plasma seminal de llama, alpaca y en menor grado de toro, induce la ovulación en las llamas hembras y favorece la formación de un cuerpo lúteo de características propias de la especie.Female llama without calf at foot, in good reproductive conditions and bearing a follicle ³7 mm in the ovaries, detected by ultrasonography, were selected (n = 64). All animals were administered 5 mg of LH(Lutropin V) to synchronize the newly emergent follicular wave.Asecond ultrasonography evaluation was done 12 days later to confirm the presence of a dominant follicle (³7mm) and then, animalswere randomlydistributed into four groups. The first three groups were i.m. injected (2 ml)with llama, alpaca and bull seminal plasma, respectively, and the fourth group was injected with PBS (phosphate basic serum) and remained as control. The occurrence of ovulation was evaluated two days later.All animals injectedwith llama and alpaca seminal plasma ovulated, whereas only 25% of llamas treated with bull seminal plasma, and none of the control group ovulated. The size of the corpus luteum 9 days after treatment did not vary among the treated groups. The results indicated that the i.m. administration of llama and alpaca seminal plasma, and in lesser degree, the bull seminal plasma induce ovulation in the llama and allow the growth of a corpus luteum to a size proper of these species
Gastrointestinal helminths in sheepdogs in farmers communities of Puno, Peru
Se determinó la frecuencia de helmintiasis gastrointestinal en perros pastores de los distritos de Ajoyani y Macusani, provincia de Carabaya, y de los distritos de Ocuvíri, Palca, Lampa y Santa Lucía, provincia de Lampa, Puno, Perú. Se colectaron muestras de heces de 352 perros cruzados, mayormente adultos, y aparentemente sanos, entre enero a marzo de 2008. La evaluación coproparasitológica hizo por el método de Flotación con solución azucarada o de Sheather y por Sedimentación Espontánea. Las muestras colectadas fueron preservadas tanto en formol al 10% como en bicromato al 2.5%. El 20.5 ± 4.2% de los perros se encontró con algún tipo de helminto gastrointestinal. La frecuencia de animales con huevos de Taenia fue de 14.5 ± 3.7%, Trichuris vulpis de 2.6 ± 1.7%, y Capillaria sp de 0.9 ± 1%, en tanto que fue de 1.4 ± 1.2% para Toxocara canis, Toxascaris leonina y Ancylostoma sp. Asimismo, la frecuencia de Sarcocystis sp. fue de 9.1 ± 3%, Entamoeba coli de 16.5 ± 3.9% e Isospora sp. de 11.9 ± 3.4%. La edad, sexo y zona agroclimática no constituyeron factores de riesgo para el parasitismo de los canes. El monoparasitismo se presentó en el 90.9% de los perros que presentaron infecciones parasitarias. El análisis de las muestras preservadas con formol al 10% y Bicromato al 2.5% dieron resultados bastante similares y, por lo tanto, moderadamente concordantes y mutuamente reemplazables al ser evaluadas mediante la prueba de Kappa y Mc Nemar.The frequency of gastrointestinal helminths in sheepdogs of Ajoyani and Macusani districts in the province of Carabaya, and in the districts of Ocuvíri, Palca, Lampa, and Santa Lucía in the province of Lampa, Puno, Peru was determined. Stool samples were collected from 352 crossbreed dogs, mostly adults and apparently healthy, during January to March 2008. The coproparasitological evaluation was done by the methods of flotation with sugar solution or Sheather’s, and by the spontaneous sedimentation technique. Samples were preserved in both 10% formaldehyde and 2.5% bichromate. The resulted showed 20.5 ± 4.2% of dogs were infected with gastrointestinal helminthes. The frequency of dogs with eggs of Taenia was 14.5 ± 3.7%, Trichuris vulpis was 2.6 ± 1.7%, Capillaria sp was 0.9 ± 1%, while for Toxocara canis, Toxascaris leonina, and Ancylostoma sp was 1.4 ± 1.2% each. Besides, the frecuency of Sarcocystis sp was 9.1 ± 3%, Entamoeba coli was 16.5 ± 3.9%, and Isospora sp was 11.9 ± 3.4%. Age, sex, and agro-climatic zone were not considered risk factors for gastrointestinal parasitism. Monoparasitism occurred in 90.9% of dogs with parasite infections. Analysis of samples preserved with 10% formaldehyde or 2.5% bichromate showed similar results and therefore both substances were considered moderately consistent and mutually replaceable according to the Kappa and Mc Nemar tests
Seed Dispersal by Chelonians: From Individuals to Communities
Plants are sessile for the most of their life cycle, but their gametes (pollen) and their propagules (seeds) can move from short to quite long distances across the landscape. The mechanism for the latter is called seed dispersal. Seed dispersal is the link between the end of reproduction and the beginning of vegetative growth, and is an important function that determines plant population persistence by influencing reproduction, population- and community dynamics. Many plant species rely on animal-mediated seed dispersal (zoochory), which thus ultimately shapes much of the world’s biodiversity. Chelonians represent one of the oldest vertebrate lineages, and have been considered one of the early frugivores and seed dispersers in evolutionary time. However, the role of chelonians as seed dispersers has been largely neglected and underestimated until very recently, despite repeated calls for the study of chelonian frugivory and seed dispersal (FSD). In my thesis, I assessed the role of chelonians as seed dispersers, from species to communities. I began by performing a review and synthesis of chelonian FSD in Chapter 1, where I mainly focused on: i) the taxonomical and geographic distribution of chelonian FSD, ii) the taxonomical distribution and traits of plants dispersed by chelonians, and iii) chelonian seed dispersal efficiency. My work is the first to provide an overview of the role of chelonians as frugivores and seed dispersers, and it highlights their importance not only from the individual and population perspective, but also from the community perspective. In Chapter 2 I then focused on Aldabra giant tortoises (Aldabrachelys gigantea) to assess their role in the seed dispersal community of Aldabra Atoll in relation to other frugivores. I provide the third study to date that evaluates the role of chelonians as seed dispersers at the community level using network analyses, and also provide the first evaluation of the role of tortoises and other dispersers in the plant–frugivore community of Aldabra Atoll. To my knowledge, my study on the Aldabra seed dispersal network is the first of its kind performed in the Western Indian Ocean – a globally important biodiversity hotspot. Furthermore, because the plant–frugivore community of Aldabra is intact and representative of the preanthropogenic assemblages that other islands used to have, the Aldabra network can serve as a template for the conservation and restoration of plant–animal interactions in these islands. In Chapter 3, I experimentally examined whether tortoise size and/or seed size affect their gut retention times. Gut retention time is one of the main traits that structure the spatial extent to which seeds can be dispersed. My study is one of the few that simultaneously evaluates both the effect of tortoise size and seed size on seed gut retention time. I demonstrate that both small and large tortoises can retain seeds for long periods, and thus spread seeds far and wide, further supporting studies that have highlighted the capacity of giant tortoises for restoration. Finally, in Chapter 4 I studied the thermoregulatory ecology of Aldabra giant tortoises, including looking at how environmental temperature may affect their role as seed dispersers, and then applied the findings about their thermoregulatory ecology in the wild to the management and husbandry of captive tortoises in Chapter 5. My work is the first to assess the thermoregulatory environment and ecology of Aldabra giant tortoises across temperature gradients. I successfully applied the knowledge gained through the latter work to inform the evaluation and management of the thermoregulatory environment of tortoises in Zürich Zoo, and provide methodological procedures that can be applied to other captive ectothermic species to provide an adequate thermal environment
The Role of Protein Structural Ensembles in Thermostability and Ligand Binding
The role of protein structural ensembles has been shown to be very important for different physical and chemical properties of proteins. The work presented in this dissertation explores two of these properties:i) Thermostability, by characterizing, at three different temperatures, the dynamics of aminoglycoside nucleotidyltransferase 4’ (ANT). This homodimeric enzyme detoxifies antibiotics. It possess two known variants, D80Y and T130K, with higher melting temperatures than the wild type. These mutations, however, would cause changes in the distributions of conformations in the ensemble and, consequently, on the dynamics of the protein. To test this hypothesis, the wild type and variants were examined by using molecular dynamics simulations and the results were compared with previous experimental information in order to characterize the similarities and differences between the, so-called, thermophilic and thermostable variants of this enzyme.ii) Ligand binding: Since proteins are in general dynamic structures, it would be expected that the effectiveness of ligand binding varies as the protein’s conformation changes. One of the most targeted protein family in the field of drug discovery/design is the G-Protein Coupled Receptor (GPCR) family. Over 30% of approved drugs target this family of proteins. This project examines, via in silico experiments, the differences in ligand binding between different conformations of GPCRs. To this end, GPCR ligand structures, actual binding (actives) and non-binding (decoys) ligands, were obtained from public databases, and eight GPCRs structures were selected to generate 5,000 conformational states for each protein. Ensemble-based docking was performed on representative structures of these 5,000 conformers and on a subset of 3,000 conformers from each of the eight proteins. Decoys and statistical analysis were incorporated in the docking simulations to test whether the sampled protein conformations can bind active ligands in greater numbers than the random selection from the pool of active and decoys. The results show that some conformations bind more ligands than other conformations, random selection, or the crystal structure. Characterizing the entire ensemble of protein conformations can improve the number of bound active ligands identified computationally, compared to random selection of compounds or docking using only a single crystal structure
Quantifying how acquired interactions with native and invasive insects influence population growth rates of a non-indigenous plant
Non-native species often acquire novel interspecific interactions, which are central to several hypotheses of invasion success, including biotic resistance and invasional meltdown. However, the outcome of these interactions is not often linked with the demographic evidence based on the full life cycle of the species. The Philippine Ground Orchid (Spathoglottis plicata) has invaded Puerto Rico and has acquired both negative and positive interspecific interactions involving the native weevil Stethobaris polita and the invasive red fire ant Solenopsis invicta, respectively. We studied a population in the Rio Abajo Forest, and asked how these interactions affect population demography by using a combination of field, experimental and modelling approaches. Stage-structured matrix population models based on four years of field observations showed that the population of S. plicata is growing at a rate (λ) of 1.05 under natural conditions. When we modified fecundity values based on experimental exclusion of weevils and ants, the control treatment showed a similar λ. Excluding weevils increased λ to 1.20, whereas the exclusion of ants decreased λ to 1.03. When we incorporate demographic and environmental stochasticity in our models, exclusion of invasive red fire ants significantly reduces the orchid abundance over time. Although weevils offer some biotic resistance to S. plicata, these effects do not prevent orchid population growth and expansion. On the other hand, invasive red fire ants have a positive effect on the invasive orchid’s λ, partially supporting the invasional meltdown hypothesis. This study presents a method that allows one to combine opposing mechanisms of species interactions within the same quantitative framework, and the results highlight the importance of considering acquired plant–animal interactions and stochastic processes when evaluating the population growth rates and dynamics of invasive plants
Island rewilding with giant tortoises in an era of climate change
Replacing recently extinct endemic giant tortoises with extant, functional analogues provide the perhaps best examples of island rewilding to date. Yet, an efficient future application of this conservation action is challenging in an era of climate change. We here present and discuss a conceptual framework that can serve as a roadmap for the study and application of tortoise rewilding in an uncertain future. We focus on three main ecological functions mediated by giant tortoises, namely herbivory, seed dispersal and nutrient cycling, and discuss how climate change is likely to impact these. We then propose and discuss mitigation strategies such as artificial constructed shade sites and water holes that can help drive and maintain the ecosystem functions provided by the tortoises on a landscape scale. The application of the framework and the mitigation strategies are illustrated with examples from both wild and rewilded populations of the Aldabra giant tortoise, Aldabrachelys gigantea, in the Western Indian Ocean