Saturday, May 1, 2010

Save the Frogs Day, April 30th 2010

Frog populations have been declining at an unexpected rate in the last few decades. Nearly one thirds of the worlds amphibians are threatened with extinction. Several species have already disappeared in the last few years.
It is now time for us to take serious steps to help conserve our Amphibians.Today being the Save the Frogs Day, lets us all decide to learn more about our little known amphibians and help in their conservation. Lets make every day a Save the Frogs Day.

Wednesday, March 3, 2010

Complete Feminization in Male Frogs due to the Use of Pesticide Atrazine

Scientist of the University of California, Berkeley and University of Cincinnati, have found that Atrazine (one of the most widely used pesticides and also a potent endocrine disruptor) exposure in adult male frogs cause complete feminization in the males. When male African Clawed Frogs (Xenopus laevis) were exposed to this pesticide, Ten percent of them developed into functional females that were able to copulate with unexposed males and produce viable eggs. The resulting larvae were all male when raised to metamorphosis and sampled, confirming that Atrazine-induced females were, in fact, chromosomal males. The Atrazine exposed males suffered from depressed testosterone, decreased breeding gland size, demasculinized laryngeal development, suppressed mating behavior, reduced spermatogenesis, and decreased fertility leading to complete feminization. Atrazine is also known to cause demasculinizes and feminizes exposed amphibian larvae, resulting in hermaphrodites.
Previous studies have shown that the Atrazine causes a reduction in sperm content in fishes like salmon, (Salmo salar) reptiles like caiman, (Caiman latirostris). The similarities between these previous findings in fish and in reptiles and the present findings in an amphibian suggest that the demasculinizing effects of atrazine are also not just species, genera, family specific but occur across vertebrate classes. The present findings exemplify that the role of Atrazine and other endocrine-disrupting pesticides, is likely a cause in the global amphibian declines.

Thursday, February 25, 2010

Cnemaspis Geckos of the Western Ghats

The Geckonid Genus Cnemaspis includes a group of diurnal geckos that ranges from South, South-East Asia and central Africa. Presently around 88 species of these Geckos have been recogniesd and the maximum diversity being from South and South-East Asia. Around 21 species of Cnemaspis geckos are found in South India of which 18 species are endemic to the Western Ghats. The Genus Cnemaspis can be easily identified from other geckos by their slender, clawed, non dilated digits and their round pupils. Although this group of geckos is fairly common throughout the Western Ghats, they remain to be one of the least understood gekonid genus of India. Recent studies on this genus have revealed several new species and have shed more light on their distribution and natural history.

During several visits throughout south India, I have been trying to understand more about this group of geckos. This note on the Cnemaspis geckos is posted to show the diversity of herpetofauna in the Western Ghats. The high endemism of the Western Ghats gives us more reasons for us to take urgent steps to protect and conserve it.

Sunday, January 10, 2010

New Light Shed On the Influence of Habitat Variables on the Distribution of Tadpoles of Nyctibatrachus major

Recent studies by K.G Girish and S.V Krishnamurthy of the Department of Environmental Science, Kuvempu University, Shimoga have found that the distribution of tadpoles and adults of the Large Wrinkled Frog, Niyctibatrachus major were influenced by canopy cover, Tree density near streams, leaf litter and humidity. Tadpoles were not found in streams were the soil, air and water temperature were high whereas tadpoles were found in streams were the canopy cover, tree density, leaf litter and humidity were high. The canopy cover, tree density and leaf litter reduced the light intensity and increased humidity providing the necessary temperature for the development of individuals. This study shows the importance of good forest cover for the development of tadpoles. Increased deforestation, timber extraction and stream modification may effect the population of this endemic frog. The IUCN has listed this species as vulnerable and if the present rate of deforestation continues, this species may well be on its way to extinction. It is by such studies that we can understand the complex relationship that a species has with its environment.

I sincerely congratulate and thank K.G Girish for sharing his findings with me and i wish him all the success in his quest to study and conserve amphibian.