Global amphibian declines

Sorting the hypotheses

James Collins, Andrew Storfer

Research output: Contribution to journalArticle

597 Citations (Scopus)

Abstract

Reports of malformed amphibians and global amphibian declines have led to public concern, particularly because amphibians are thought to be indicator species of overall environmental health. The topic also draws scientific attention because there is no obvious, simple answer to the question of what is causing amphibian declines? Complex interactions of several anthropogenic factors are probably at work, and understanding amphibian declines may thus serve as a model for understanding species declines in general. While we have fewer answers than we would like, there are six leading hypotheses that we sort into two classes. For class I hypotheses, alien species, over-exploitation and land use change, we have a good understanding of the ecological mechanisms underlying declines; these causes have affected amphibian populations negatively for more than a century. However, the question remains as to whether the magnitude of these negative effects increased in the 1980s, as scientists began to notice a global decline of amphibians. Further, remedies for these problems are not simple. For class II hypotheses, global change (including UV radiation and global climate change), contaminants and emerging infectious diseases we have a poor, but improving understanding of how each might cause declines. Class II factors involve complex and subtle mechanistic underpinnings, with probable interactions among multiple ecological and evolutionary variables. They may also interact with class I hypotheses. Suspected mechanisms associated with class II hypotheses are relatively recent, dating from at least the middle of the 20th century. Did these causes act independently or in concert with preexisting negative forces of class I hypotheses to increase the rate of amphibian declines to a level that drew global attention? We need more studies that connect the suspected mechanisms underlying both classes of hypotheses with quantitative changes in amphibian population sizes and species numbers. An important step forward in this task is clarifying the hypotheses and conditions under which the various causes operate alone or together.

Original languageEnglish (US)
Pages (from-to)89-98
Number of pages10
JournalDiversity and Distributions
Volume9
Issue number2
DOIs
StatePublished - Mar 2003

Fingerprint

Amphibians
sorting
amphibian
amphibians
Emerging Communicable Diseases
Environmental Health
emerging diseases
Climate Change
infectious disease
Population Density
global change
introduced species
land use change
indicator species
ultraviolet radiation
global climate
population size
climate change
Radiation
pollutant

Keywords

  • Amphibian declines
  • Complexity
  • Sorting hypotheses
  • Time scale

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Ecology

Cite this

Global amphibian declines : Sorting the hypotheses. / Collins, James; Storfer, Andrew.

In: Diversity and Distributions, Vol. 9, No. 2, 03.2003, p. 89-98.

Research output: Contribution to journalArticle

Collins, James ; Storfer, Andrew. / Global amphibian declines : Sorting the hypotheses. In: Diversity and Distributions. 2003 ; Vol. 9, No. 2. pp. 89-98.
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