36 research outputs found
Herpetofauna del Parque Sierra de Nanchititla, estado de M茅xico, M茅xico. Lista, distribuci贸n y conservaci贸n
Get PDFThe Sierra de Nanchititla Natural Park is located in the southwestern corner of the state of Mexico. Most of the park is contained in the western half of the municipality of Tejupilco, bordered on the west by the states of Michoacan and Guerrero. Physiographically it is located in the Province of Sierra Madre del Sur, in the Subprovince of Depresi贸n del rio Balsas, and represents a transition zone of climate, flora and fauna. A total of 48 species were registered in the Nanchititla Park, including 20 amphibians and 28 reptiles, of which 21 (44%) are new records for the localit
La introducci贸n y el cultivo de la rana toro (Rana catesbeiana). 驴Un atentado a la biodiversidad de M茅xico?
Get PDFThe bullfrog (Rana catesbeiana) has a wide natural distribution in North America, as well as having been introduced into at least 16 countries for commercial purposes. In Mexico, this species was introduced, without any controls, into at least sixteen states. No preliminary studies were conducted to determine the possible effects and changes to the environment that might be caused by its introduction. The introduction of this frog into the environment, either through escape from cultivation or through indiscriminate releases, has been assesed in several countries, and represents a serious threat to the ecosystem and biodiversity. We recommend that the time is long overdue to undertake an inventory of introduction sites of this species in Mexico, and to evaluate the environmental perturbations that have occurred owing to its introduction. We also recommend that the feasibility of controlling these introduced populations should be assessed, with the ultimate goal of possibly eradicating them altogether. The cultivation of indigenous species of frogs would seem to be a desirable alternative. There are thirty three species of ranid frogs in Mexico, several of which attain large sizes and might be commercially viable options. The cultivation of native species would eliminate the problems associated with exotic introductions
Reproducci贸n ex situ en Ambystoma Granulosum y Ambystoma Lermaense (Amphibia: Ambystomatidae)
Get PDFAmphibians are disappearing worldwide. Several species have been lost, and thousands are in danger of extinction. Of the threatened species, some can not be protected in their own natural habitat, therefore it is imperative to accomplish ex-situ conservation actions that assure its preservation. Ambystoma granulosum and Ambystoma lermaense, are species in high priority to be protected by mean of this conservation strategy, since they are endemic species of Mexico and with a concern conservation status. Both species have been little studied, therefore in this study we investigated reproductive aspects that are vital for its conservation, as reproduction in laboratory, and hormonal induction with human chorionic gonadotrophin (hCG). Our results showed not significant difference in the sex morphology for both species, except for the swollen vent in the cloacal region of males. The reproductive cycle is annual and synchronic in males and females, with a maximum of activity from May to September. We obtained clutches only from couples of A. granulosum without hormonal induction in variable numbers with an average of 664 卤 325(SD) eggs and a fecundity from 40 to 90%. We obtained nine clutches from couples of Ambystoma granulosum with hCG induction ranging between 17 and 1182 eggs. In couples of Ambystoma lermaense induced, were obtained 16 clutches, ranging between 110 and 1691 eggs. We analyzed possible causes for the variability in fertility of eggs obtained by induction.Los anfibios est谩n desapareciendo a nivel mundial. Varias especies se han perdido y miles m谩s est谩n en peligro de extinci贸n. De las especies que est谩n amenazadas, varias no se pueden proteger en su medio natural, por lo que es urgente realizar acciones de conservaci贸n ex situ que aseguren su preservaci贸n. Ambystoma granulosum y Ambystoma lermaense, son especies prioritarias para iniciar esta estrategia de conservaci贸n, ya que son especies end茅micas de M茅xico y con un estatus de conservaci贸n preocupante. Ambas especies han sido poco estudiadas, por lo que en este estudio se investigaron, los aspectos reproductivos que son vitales para la conservaci贸n, logrando reproducir a la especie en condiciones de laboratorio de manera natural o espont谩nea, o por la estimulaci贸n hormonal con Gonadotropina Cori贸nica (hCG). Los resultados obtenidos nos indican que no existen diferencias significativas en la morfolog铆a de machos y hembras en ambas especies, excepto por el engrosamiento de la regi贸n cloacal en los machos. El ciclo reproductivo es anual y sincr贸nico en machos y hembras, con actividad m谩xima entre los meses de mayo a septiembre. Las puestas en parejas sin inducci贸n hormonal fue variable con promedio de 664 卤 325 (DE) huevos y el porcentaje de fecundidad fue de 40 al 90%. En parejas de Ambystoma granulosum con inducci贸n de hCG se obtuvieron nueve puestas variables entre 17 y 1182 huevos. En parejas de A. lermaense inducidos, se obtuvieron 16 puestas, las que variaron entre 110 y 1691 huevos. La fertilidad de los huevos inducidos fue muy variable analiz谩ndose posibles causas
