oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 24 )

2018 ( 46 )

2017 ( 50 )

2016 ( 61 )

Custom range...

Search Results: 1 - 10 of 43004 matches for " Ricardo Rodríguez-Estrella "
All listed articles are free for downloading (OA Articles)
Page 1 /43004
Display every page Item
EFECTOS DE LA FRAGMENTACIóN DEL MATORRAL DESéRTICO SOBRE POBLACIONES DEL AGUILILLA COLA-ROJA Y EL CERNíCALO AMERICANO EN BAJA CALIFORNIA SUR, MéXICO
Romeo TINAJERO,Ricardo RODRíGUEZ-ESTRELLA
Acta zoológica mexicana , 2012,
Abstract: Para evaluar el efecto de la fragmentación del desierto sobre especies de poblaciones residentes y migratorias, durante 2008 y 2009 se realizaron muestreos mensuales de dos especies de aves rapaces, el aguililla cola-roja Buteo jamaicensis y el cernícalo americano Falco sparverius. Los muestreos se realizaron en áreas naturales continuas y en áreas fragmentadas por actividad agrícola en el matorral desértico de Baja California Sur. En total se registraron en 1,806 ocasiones las dos especies. La más común fue el cernícalo americano con 1,164 (64.4%) registros (los cuales fueron 51% en área fragmentada y 49% área natural) y el aguililla cola-roja con 642 registros (35.6%) (70% en área fragmentada y 30% en área natural). Se estimaron las abundancias relativas y la densidad, las cuales no variaron durante la primavera y verano para el aguililla cola-roja, pero sus abundancias y densidades fueron mayores en las áreas fragmentadas durante oto o e invierno. Por otro lado, la abundancia del cernícalo americano fue similar entre áreas en todas las temporadas del a o, mientras que la densidad fue similar en primavera, verano e invierno, pero fue mayor en el área fragmentada durante el oto o. Se encontró que el matorral desértico y sus áreas fragmentadas dentro de una matriz agrícola en Baja California Sur es un hábitat importante para las poblaciones migratorias de ambas especies de rapaces. Se discute sobre la tolerancia de las dos especies en función de su tama o y selección de hábitat para anidar y forrajear, así como los efectos de la fragmentación del desierto sobre su abundancia y densidad en el sur de la península de Baja California.
Using population viability analysis for management recommendations of the endangered endemic peninsular pronghorn
CANCINO, Jorge;RODRíGUEZ-ESTRELLA, Ricardo;MILLER, Philip;
Acta zoológica mexicana , 2010,
Abstract: a case study on the viability of small populations with a restricted distribution and reduction in habitat quality is addressed using the peninsular pronghorn (antilocapra americana peninsularis) of baja california peninsula, mexico. the present size of its wild population is less than 250 individuals, being in an iucn "critically endangered" status. captive management of peninsular pronghorn began in 1998 in el vizcaino desert with 22 founders. we predicted future trends in the pronghorn population, and assessed the risk of extinction through population viability analysis (pva) using vortex. deterministic and stochastic factors designed to simulate human activity on the landscape were evaluated for their impact on this endemic taxon. the concept of "supportive breeding" was assessed. the results of pva simulations indicate that removal of founder animals to initiate the captive breeding did not significantly reduce the viability of the wild population. however, a population size <100 individuals greatly increase the risk of extinction. also, one of the most important factors for the viability of the peninsular pronghorn population is the survival of fawns. the risk of extinction can be significantly reduced using "supportive breeding". we propose that the likelihood of successful population management of peninsular pronghorn could be increased establishing a number of subpopulations across the species' historic range and, even more importantly, the establishment of ecologically functional connections between these subpopulations to create a proper metapopulation. captive breeding can be an important factor to decrease the probability of extinction of this subspecies.
USING A POPULATION VIABILITY ANALYSIS FOR MANAGEMENT RECOMMENDATIONS OF THE ENDANGERED ENDEMIC PENINSULAR PRONGHORN
Jorge Cancino,Ricardo Rodríguez-Estrella,Philip Miller
Acta zoológica mexicana , 2010,
Abstract: Se evaluó el riesgo de extinción de la población del berrendo peninsular (Antilocapra americana peninsularis) en la península de Baja California, México que presenta distribución restringida y deterioro en la calidad de su hábitat. En el a o 2000, el tama o de la población silvestre del berrendo peninsular era menor a 250 individuos. Se desarrolló un análisis de viabilidad de poblaciones (PVA) usando Vortex, que incluyó variables determinísticas y estocásticas, e información de 25 a os para proyectar cambios en la población, y evaluar su riesgo de extinción. Con el PVA se evaluó el concepto de "Reproducción de Apoyo". En 1998 se inició el manejo en cautiverio del berrendo peninsular con 22 animales fundadores. Los modelos sugirieron que una población de menos de 100 individuos incrementa considerablemente el riesgo de extinción, siendo uno de los factores más importantes para la viabilidad de la población la sobrevivencia de las crías. Se propone que el éxito del manejo de la población del berrendo peninsular puede incrementarse estableciendo subpoblaciones dentro de su rango histórico de distribución con una perspectiva metapoblacional donde se conecten las subpoblaciones. Y se concluye que la reproducción en cautiverio puede ser un factor importante para disminuir la probabilidad de extinción de esta subespecie.
Genetic Diversity of the Endemic Xantus’ Hummingbird Using 16 Novel Polymorphic Microsatellite Loci, and Their Cross Amplification between Six Related Species  [PDF]
Cristina González-Rubio Sanvicente, Ricardo Rodríguez-Estrella, Oscar Adrián Lozano-Garza, Francisco J. García-De-León
Open Journal of Genetics (OJGen) , 2016, DOI: 10.4236/ojgen.2016.61003
Abstract: A set of 16 microsatellite loci was developed and characterized for the Xantus’ hummingbird (Hylocharis xantusii) by using 454 next-generation sequencing. Twenty-five H. xantusii samples from one population were genotyped; all loci were polymorphic, with the number of alleles ranging from three to ten. The mean observed heterozygosity was 0.681 for all loci. No significant linkage disequilibrium was detected, but five loci (Hxan05, 06, 09, 13 and 14) showed deviation from Hardy-Weinberg equilibrium. These microsatellite loci are the first to be characterized for H. xantusii. A moderate to high level of cross-species amplification was observed across the six hummingbird species (31% - 87.5%), with the best cross amplification results observed in the closest related species (H. leucotis, Cynanthus latirostris, Calypte costae). The availability of these molecular tools allows assessing questions integrating population genetics, ecology, conservation, and evolutionary history for H. xantusii and for other phyogenetically related species.
Recent increase in the distribution of the snail kite (Rostrhamus sociabilis) along the central Pacific Coast of México Incrementos de la distribución del gavilán caracolero (Rostrhamus sociabilis) en la costa del Pacífico central de México
Salvador Hernández-Vázquez,Ricardo Rodríguez-Estrella,Francisco Ramírez-Ortega,Juan Loera
Revista mexicana de biodiversidad , 2013,
Abstract: New records of the snail kite (Rostrhamus sociabilis) are presented for the central Pacific Coast of Mexico. From April 2010 to August 2011, weekly or biweekly surveys were made through several wetlands of coastal Jalisco and Colima. We recorded 32 snail kites from October 2010 to August 2011. The recordings were in 8 wetlands. In all wetlands there was only 1 individual, except in the lagoons El Aguacate (June 2010) and El Tule (August 2012), where we recorded 3 and 5 individuals, respectively. Although we did not find any nests, we believe reproduction of snail kites is currently occurring because of the observed adult behavior (carrying small branches in its feet) and the records of juveniles during the month of February to July, a time corresponding to the breeding season of the species in Florida. Our records expand the distribution of the snail kite in Mexico as much as 900 km northwest of the previously published distribution of the species. Presentamos nuevas observaciones del gavilán caracolero (Rostrhamus sociabilis) para la costa del Pacífico central mexicano. De abril de 2010 a agosto de 2011 se realizaron visitas semanales o quincenales a varios humedales costeros de Jalisco y Colima. Se observaron 32 individuos entre octubre del 2010 y agosto del 2011 en 8 humedales. En todos los humedales se registró sólo 1 individuo, excepto en las lagunas El Aguacate (junio de 2011) y El Tule (agosto de 2012), donde se observaron 3 y 5 individuos, respectivamente. Aunque no se han registraron nidos, consideramos que es probable que la reproducción del gavilán caracolero está ocurriendo actualmente en la región debido a la conducta observada de algunos adultos (p. ej. llevando ramas peque as en sus patas) y a la presencia de los juveniles durante los meses de febrero a julio, tiempo en el que ocurre la anidación de la especie en Florida. Nuestras observaciones incrementan la distribución del gavilán caracolero en México a cerca de 900 km al noroeste de su distribución registrada previamente.
The problems of overexploitation of aquifers in semi-arid areas: the Murcia Region and the Segura Basin (South-east Spain) case
T. Rodríguez-Estrella
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-5729-2012
Abstract: A general analysis of the problems arising from aquifer exploitation in semi-arid areas such as the Autonomous Region of Murcia, which belongs to the Segura Basin is presented, with particular reference to the Ascoy-Sopalmo aquifer, which is the most overexploited aquifer in Spain. It has suffered intense overabstraction over the last forty years, given renewable water resources of 2 Mm3 yr 1 and abstractions amounting to as much as 55 Mm3 yr 1. This has resulted in the drying of springs, continuous drawdown of water levels (5 m yr 1); piezometric drops (over 30 m in one year, as a consequence of it being a karstic aquifer); increase in pumping costs (elevating water from more than 320 m depth); abandoning of wells (45 reduced to 20), diminishing groundwater reserves, and deteriorating water quality (progressing from a mixed sodium bicarbonate-chloride facies to a sodium chloride one). This is a prime example of poor management with disastrous consequences. In this sense, a series of internal measures is proposed to alleviate the overexploitation of this aquifer and of the Segura Basin, with the aim of contributing to a sustainable future.
Dieta estacional del Coyote Canis latrans durante el periodo 1996 -1997 en el desierto de Vizcaíno, Baja California Sur, México
Karina M. Grajales Tam,Ricardo Rodríguez Estrella,Jorge Cancino Hernández
Acta zoológica mexicana , 2003,
Abstract: Se estudió la dieta del coyote (Canis latrans) en el Desierto de Vizcaíno. El estudio se realizó durante las temporadas de verano e invierno de 1996 y 1997 respectivamente. Por medio del análisis de 302 excretas, se identificaron 8963 presas totales, 64 taxa animales y 10 de vegetales. La mayor proporción correspondió a los artrópodos, constituyendo un 95% de las presas consumidas durante el invierno. Las proporciones en relación al tama o de presa se ubicaron en el intervalo de 0-20 g, aunque en relación al mayor aporte de biomasa las presas estuvieron entre los 1280-2560 g. El coyote se comportó como un consumidor generalista y oportunista, con una tendencia hacia la especialización en el consumo de artrópodos
Alimentación del pez tropical Gobioides broussonnetii (Pisces: Gobiidae) en la Laguna de Unare, Venezuela
Rodríguez,José; Villamizar,Estrella;
Revista de Biología Tropical , 2006,
Abstract: diet of the tropical fish gobioides broussonnetii (pisces: gobiidae) at laguna de unare, venezuela. unare lagoon is one of the most important fishery coastal ecosystems in venezuela. for the past 10 years, changes in its hydrological regime have affected the physiochemical characteristics of the water with important consequences on its faunal composition and abundance. an example of such variation is the abundant presence of a fish species, gobioides broussonnetii, recently registered in this ecosystem. the ecology of this species must be studied to identify new ecological processes occurring in the lagoon. detritus is the most important component of the g. broussonnetii diet, followed by plant and animal items. the species is a primary detritivorous consumer and this may be associated with its activity pattern (morning): it may be an occasional visitor because it was not captured regularly in the monthly samplings. rev. biol. trop. 54 (4): 1093-1098. epub 2006 dec. 15.
Alimentación del pez tropical Gobioides broussonnetii (Pisces: Gobiidae) en la Laguna de Unare, Venezuela
José Rodríguez,Estrella Villamizar
Revista de Biología Tropical , 2006,
Abstract: Diet of the tropical fish Gobioides broussonnetii (Pisces: Gobiidae) at Laguna de Unare, Venezuela. Unare Lagoon is one of the most important fishery coastal ecosystems in Venezuela. For the past 10 years, changes in its hydrological regime have affected the physiochemical characteristics of the water with important consequences on its faunal composition and abundance. An example of such variation is the abundant presence of a fish species, Gobioides broussonnetii, recently registered in this ecosystem. The ecology of this species must be studied to identify new ecological processes occurring in the lagoon. Detritus is the most important component of the G. broussonnetii diet, followed by plant and animal items. The species is a primary detritivorous consumer and this may be associated with its activity pattern (morning): It may be an occasional visitor because it was not captured regularly in the monthly samplings. Rev. Biol. Trop. 54 (4): 1093-1098. Epub 2006 Dec. 15.
Asociación del nivel socioeconómico con la higiene bucal en preescolares bajo el programa de odontología preventiva del IMSS en Campeche
Medina-Solís, Carlo Eduardo;Segovia-Villanueva, América;Estrella-Rodríguez, Ramón;Maupomé, Gerardo;ávila-Burgos, Leticia;Pérez-Nu?ez, Ricardo;
Gaceta médica de México , 2006,
Abstract: objective. determine the association between socioeconomic status and oral hygiene in the primary dentition of preschool children. materials and methods. we undertook a cross-sectional study of 1,303 children attending 10 schools in campeche, mexico. every child was clinically examined in a portable dental chair by one of four examiners. we used a questionnaire addressed to the mothers to collect data on socioeconomic and socio demographic variables-including attitudinal variables dealing with the perceived importance of oral health. oral hygiene was assessed appraising the frequency of tooth brushing and the presence of dental plaque. data analysis included non-parametric tests using stata 8.2?. results. mean age was 4.36 ± 0.79 years and 48.3% of children were girls. of the study population, 17.8% (n= 232) were classified as having inadequate oral hygiene, 50.9% (n= 663) having moderate oral hygiene, and 31.3% (n= 408) having adequate oral hygiene. children who were rated more frequently as having inadequate hygiene (p < 0.05) had mothers with a negative attitude toward oral health, were users only of public medical insurance (as opposed to users of private services), and had not used dental services in the year prior to the study. finally, we observeda decrease in the adequacy of oral hygiene associated with a decrease in socioeconomic status. conclusions. our findings showed that oral hygiene was closely associated with socioeconomic status. this implies that if a reduction of oral health inequalities is to be achieved, the strategies andresources targeting these goals must take into account the existing differences between population groups with more or fewer social disadvantages.
Page 1 /43004
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.