RESUMO
Correlative ecological niche models (ENMs) estimate species niches using occurrence records and environmental data. These tools are valuable to the field of biogeography, where they are commonly used to infer potential connectivity among populations. However, a recent study showed that when locally relevant environmental data are not available, records from patches of suitable habitat protruding into otherwise unsuitable regions (e.g., gallery forests within dry areas) can lead to overestimations of species niches and their potential distributions. Here, we test whether this issue obfuscates detection of an obvious environmental barrier existing in northern Venezuela - that of the hot and xeric lowlands separating the Península de Paraguaná from mainland South America. These conditions most likely promote isolation between mainland and peninsular populations of three rodent lineages occurring in mesic habitat in this region. For each lineage, we calibrated optimally parameterized ENMs using mainland records only, and leveraged existing habitat descriptions to assess whether those assigned low suitability values corresponded to instances where the species was collected within locally mesic conditions amidst otherwise hot dry areas. When this was the case, we built an additional model excluding these records. We projected both models onto the peninsula and assessed whether they differed in their ability to detect the environmental barrier. For the two lineages in which we detected such problematic records, only the models built excluding them detected the barrier, while providing additional insights regarding peninsular populations. Overall, the study reveals how a simple procedure like the one applied here can deal with records problematic for ENMs, leading to better predictions regarding the potential effects of the environment on lineage divergence.
RESUMO
La linfadenitis caseosa (LC) es una enfermedad infecciosa de carácter crónico causada por Corynebacterium pseudotuberculosis; afecta a pequeños rumiantes y genera pérdidas económicas por reducción del peso, eficiencia reproductiva, producción de leche y lana, decomiso de canales y depreciación de pieles. Dada la importancia socioeconómica de la producción caprina en el estado Falcón (Venezuela), el objetivo de esta investigación fue caracterizar epidemiológicamente la enfermedad en rebaños de la península de Paraguaná. La investigación es de carácter descriptivo. La fase de campo se efectuó durante seis semanas, tiempo en que se inspeccionaron los ganglios linfáticos superficiales, de los que se obtuvieron 71 muestras de secreción purulenta en aquellos animales en los que se presumía padecían de LC, según las manifestaciones clínicas. Una vez en el laboratorio, los especímenes se analizaron bacteriológicamente; se compararon los aislamientos de C. pseudotuberculosis con la cepa de referencia ATCC 19410. Solo se detectó como factor de riesgo de la LC (p < 0,05) la procedencia de los caprinos según la unidad de producción, de las que se observaron con las mayores prevalencias en aquellas ubicadas en el municipio Falcón, entre las cuales las lesiones en los ganglios preescapulares fueron las más frecuentes (p < 0,05) entre todos los animales diagnosticados. Se identificaron cepas con resistencia a penicilina, trimetoprima-sulfametoxazol y novobiocina. Estos resultados son de importancia para la concientización de los productores, dado que esta actividad es de vital trascendencia en la región y en muchos casos se pudo constatar el desconocimiento del tema.
Caseous lymphadenitis (CL) is a chronic infectious disease caused by Corynebacterium pseudotuberculosis; it affects small ruminants and generates economic loss due to a reduction in weight, reproductive performance, milk and wool production forfeiture, and depreciation of skins. Given the socio-economic importance of goat production in the Falcón state (Venezuela), this research aimed to epidemiological^ characterize the disease in herds in the Paraguaná peninsula. The research is descriptive. Field work lasted six weeks, during which superficial lymph nodes were inspected, and 71 samples of purulent discharge were obtained from animals suspected to suffer from CL, according to their clinical manifestations. Back in the laboratory, specimens were bacteriologically analyzed; C. pseudotuberculosis isolates were compared with the reference strain ATCC 19410. The only risk factor detected for CL (p < 0.05) was the origin of goats by production units; those with the highest prevalence were located in the municipality of Falcón. Injuries in subscapular lymph nodes were the most frequent (p < 0.05) among the diagnosed animals. Penicillin, trimethoprim-sulfamethoxazole, and novobiocin-resistant strains were identified. These results are important to raise awareness among producers, given that this activity is of vital importance for the region and in many cases ignorance on the subject was evidenced.
A linfadenite caseosa (LC) é uma doença infecciosa de caráter crônico, causada por Corynebacterium pseudotuberculosis; afeta a pequenos ruminantes e gera perdas econômicas por redução do peso, eficiência reprodutiva, produção de leite e lã, confisco de canais e depreciação de peles. Devido à importância socioeconómica da produção caprina no estado Falcón (Venezuela), o objetivo desta pesquisa foi caracterizar a epidemiologia da doença em rebanhos da península de Paraguaná. A pesquisa é de caráter descritivo. A fase de campo foi realizada durante seis semanas, tempo em que se inspecionaram os gânglios linfáticos superficiais, do que se obtiveram 71 amostras de secreção purulenta em aqueles animais nos que se presumia padeciam de LC, segundo as manifestações clínicas. Já no laboratório, os espécimenes se analisaram bacteriologicamente; se compararam os isolamentos de C. pseudotuberculose com a cepa de referência ATCC 19410. Somente se detectou como fator de risco da LC (p < 0,05) a procedência dos caprinos segundo a unidade de produção, das que se observaram com as maiores prevalências naquelas situadas no município Falcón, entre as quais as lesões nos gânglios pré-escapulares foram as mais frequentes (p < 0,05) entre todos os animais diagnosticados. Identificaram-se cepas com resistência a penicilina, trimetoprima-sulfametoxazol e novobiocina. Estes resultados são importantes para a conscientização dos produtores, sendo que esta atividade tem uma vital transcendência na região e em muitos casos pôde-se constatar o desconhecimento do tema.
RESUMO
En Punta El Chaure por una extensión de 263 m se ubica un estrato de espesor variable entre 0,23 y 1,35 m. de dunas fósiles presumiblemente pleistocenas; hacia el NE, el depósito permanece recubierto alternativamente por sedimentos eólicos actuales y hacia el SW entran en contacto con los acantilados inactivos de El Chaure. La existencia de este modelado plantea consideraciones paleogeográficas de interés para la evolución de la costa norte de Paraguaná. Los objetivos del trabajo son: a) Establecer las características sedimentológicas de las formas topográficas estudiadas b) Identificar los procesos bajo los cuales evolucionan actualmente. c) Caracterizar las formas geomorfológicas actuales. La metodología utilizada se basa en trabajo de campo, análisis petrográfico de secciones finas, tamizado en seco, curvas granulométricas, parámetros estadísticos, análisis morfoscópico y calcimetría. Se concluye que las eolianitas en campo, se presentan como areniscas de grano medio a fino, bien cementadas de color crema con estratificación cruzada, observándose en las secciones finas abundante cuarzo detrítico. La redondez varía desde subangular en las tallas medias a subredondeada en las más gruesas. La selección es moderada a pobre, la asimetría negativa y la curtosis leptocúrtica. Estos resultados difieren de los depósitos actuales. El contenido de carbonato de calcio es superior al 50 por ciento en ambos casos. Las dunas fósiles presentan rasgos de morfología cárstica que favorecen el desmantelamiento.
A probable Pleistocene fossil dunes layer is located at Punta El Chaure, its thickness varies from 0,23 to 1,35 m and its extension goes about 263 m towards NE, the layer is covered by aeolian sediments and it makes contact with inactive cliff to SW. The presence of these deposits raises important paleogeographic considerations for Paraguaná north coast evolution studies. The objectives of this research are: a) to establish sedimentary characteristics of these topographic forms, b) to identify present evolution processes, and c) to characterize actual geomorphologic forms. The methodology used was based on field work, petrography analysis of thin sections, dry sieving, statistic parameters, granulemetric curves, morphologic analysis, and calcium content. Conclusions: Cream eolianites are found in field with cross stratification and good cementation of sandstone. Main grain size ranges from medium to fine. Abundant detritic quartz is observed under microscope. Roundness varies from sub-angular in medium sizes to subrounded in thick ones. Statistic parameters show a selection from moderate to poor, negative asymmetry and leptokurtic kurtosis. These results differ from actual deposits. The content of Calcium Carbonate is higher than 50 percent in both cases. Fossil dunes show karsts morphology traits which facilitate dismantlement.
