Amphibians: Tough Times

Dec. 17, 2010, 11:50 a.m.

Dec 8, 2010
Golden Toad thought to be extinct.
Golden Toad thought to be extinct.
This article has been reviewed by the following Topic Editor: Margaret Swisher

Amphibians have not fared very well in recent years. Since 1980, 32.3% of amphibious species (1,856 out of 5,743 known species) have declined in population size, 7.4% sit on the brink of extinction, and between 0.2% and 2.1% have already disappeared. [1] This contrasts with birds and mammals for which, respectively, 12% and 23% have declined over the same period, 1.8% and 3.8% are near extinction, and 0.05% and 0% have already disappeared.

Most of the threatened amphibian species belong to four families: Bufonidae (true toads), Hylidae (tree frogs), Leptodactylidae (neotropical frogs), and Ranidae (true frogs). [1] Loss of suitable habitat has been a critical factor in the decline of all four families. In addition, 21 species in the Ranidae family are threatened by overexploitation from excessive harvesting for human consumption, especially in Asia. At first, the decline in populations of 80 species in the Bufonidae, 38 species in the Hylidae, and 47 species in the Leptodactylida seemed puzzling because it was occurring even in areas protected from habitat loss or human exploitation. Recent evidence, however, implicates global warming. [2]

An orange-eyed tree frog. Tree frogs, like many other species of amphibians, are in decline worldwide, and global warming has been implicated as part of the reason. Photo: / CC BY-SA 2.0

A pathogenic fungus Batrachochytrium dendrobatidis infects many amphibians. Within 6 months after B. dendrobatidis initially arrived at a site in Panama, approximately 80% of the individuals from over half of the amphibian species had died from the resulting infections. [3] Temperatures at many tropical highland localities are warming, and as they approach the growth optimum of the fungus, outbreaks occur and extinctions increase.

[1] Stuart, S. N., J. S. Chanson, N. A. Cox, B. E. Young, A. S. L. Rodrigues, D. L. Fischman, and R. W. Waller (2004) Status and trends of amphibian declines and extinctions worldwide. Science 306:1783-1786.

[2] Pounds, J. A., M. R. Bustamante, L. A. Coloma, J. A. Consuegra, M. P. L. Fogden, P. N. Foster, E. La Marca, K. L. Masters, A. Merino-Viteri, R. Puschendorf, S. R. Ron, G. A. Sanchez-Azofeifa, C. J. Still, and B. E. Young (2006) Widespread amphibian extinctions from epidemic disease driven by global warming. Nature 439:161-167.

[3] Lips, K. R., F. Brem, R. Brenes, J. D. Reeve, R. A. Alford, J. Voyles, C. Carey, L. Livo, A. P. Pessier, and J. P. Collins (2006) Emerging infectious disease and the loss of biodiversity in a Neotropical amphibian community. Proceedings of the National Academy of Sciences of the United States of America 103: 3165-3170.



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