Amphibians, a unique group of vertebrates containing over 6,300 known species, are threatened worldwide. A recent assessment of the entire group found that nearly one-third (32%) of the world%u2019s amphibian species are threatened, representing 1,856 species. Amphibians have existed on earth for over 300 million years, yet in just the last two decades there have been an alarming number of extinctions, nearly 168 species are believed to have gone extinct and at least 2,469 (43%) more have populations that are declining. This indicates that the number of extinct and threatened species will probably continue to rise (Stuart et al. 2004).
Amphibian diversity is highest in the tropics and Brazil has the most described species at 811 species. By contrast, the United States is nearly the same size as Brazil but has 292 species (as of January 22, 2009).
Clearly, the most important factor leading to amphibian population declines is habitat destruction. When forests are cleared it is no surprise that species that once lived there disappear. What is alarming is that there are many cases where the habitat is protected and amphibians are still disappearing. The causes for recent amphibian declines are many, but an emerging disease called chytridiomycosis and global climate change are thought the be the biggest threats to amphibians. Chytridiomycosis is a disease caused by the fungal chytrid pathogen
Batrachochytrium dendrobatidis. This pathogen is associated with the global loss of hundreds of species of amphibians and represents a spectacular loss of biodiversity, some say the worst in recorded history.
