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Forgetting Habitat Loss in Amphibian Extinctions – Missing the Forest for the Disease

Posted by pbio on 07 May 2009 at 22:23 GMT

Author: David Bickford
Position: Assistant Professor
Institution: National University of Singapore
Additional Authors: Lee TM, Koh LP, Sodhi NS, Diesmos AC, Brook BW, CH Sekercioglu, Bradshaw CJA
Submitted Date: March 28, 2008
Published Date: April 4, 2008
This comment was originally posted as a “Reader Response” on the publication date indicated above. All Reader Responses are now available as comments.

The recent review by Lips et al. on climate change triggering chytrid fungus outbreaks in Neotropical amphibians is an excellent investigation. Despite their comprehensive analysis and conclusion that the link between climate change and disease is tenuous, the paper epitomizes a current trend in amphibian extinction research: ignoring the primary factor. Habitat loss is clearly the most important driver of amphibian extinction, compounded by accelerating rates of forest loss. While we commend the authors for a rigorous treatment of an interesting and important issue, we must ensure we do not miss the forest for the trees.
Recent amphibian research and publications has shifted to topics that attract funding and top-tier publications (e.g., Berger et al. 1998; Blaustein and Kiesecker 2002; Pounds et al. 2006). We do not contest that climate change and disease are important drivers of amphibian decline; however, we do take issue with lack of recognition that these stressors are of relatively lower priority compared to habitat loss.
Recent work has clearly shown that amphibian threat and decline risk are determined primarily by a species’ range size and affected by habitat loss and fragmentation (Cooper et al. 2008; Sodhi et al. 2008). While it is fascinating that evidence to support climate change driving amphibian chytridiomycosis outbreaks is scant, attention to this issue draws awareness away from the highest conservation priority. Global net forest loss is occurring at a rate of 7.3 million ha year-1 (FAO , 2005), an area greater than the range of 73 % of the combined 2583 amphibian species analyzed by Sodhi et al. (2008).
To emphasize our point, we examined prevalence of ‘habitat loss/degradation (human-induced)’ and ‘pathogens/parasites’ as major threat types among amphibians compiled by the Global Amphibian Assessment in the IUCN Red List database ( Of 5880 extant amphibians, 3404 (58 %) are threatened by habitat loss (55 % listed as Vulnerable, Endangered, Critically Endangered, and Data Deficient; hereafter ‘red-listed’), only 78 (1 %) are affected by diseases (79 % of which are ‘red-listed’), and 461 (8 %) are impacted both by habitat loss and disease (85 % of which are ‘red-listed’).
We strongly argue that the best use of finite conservation resources is to concentrate on habitat protection and the synergies between habitat degradation and other stressors such as disease and climate change. If we fail to target the most important drivers of extinction and decline, we risk losing many more amphibians than have already disappeared.

Berger L, Speare R, Daszak P, Green DE, Cunningham AA et al. (1998) Chytridiomycosis causes amphibian mortality associated with population declines in the rain forests of Australia and Central America. Proceedings of the National Academy of Sciences of the United States of America 95(15): 9031-9036.
Blaustein AR, Kiesecker JM (2002) Complexity in conservation: lessons from the global decline of amphibian populations. Ecol Lett 5(4): 597-608.
Cooper N, Bielby J, Thomas GH, Purvis A (2008) Macroecology and extinction risk correlates of frogs. Global Ecology and Biogeography 17(2): 211-221.
FAO (2005). State of the World's Forests. Rome: Food and Agricultural Organisation of the United Nations
Lips KR, Diffendorfer J, Mendelson JR, Sears MW (2008) Riding the wave: reconciling the roles of disease and climate change in amphibian declines. PLoS Biology 6(3): e72.
Pounds JA, Bustamante MR, Coloma LA, Consuegra JA, Fogden MPL et al. (2006) Widespread amphibian extinctions from epidemic disease driven by global warming. Nature 439(7073): 161-167.
Sodhi NS, Bickford D, Diesmos AC, Lee TM, Koh LP et al. (2008) Measuring the meltdown: drivers of global amphibian extinction and decline. PLoS One 3(2): e1636. doi:10.1371/journal.pone.0001636

No competing interests declared.