The decline in amphibian populations is an ongoing mass extinction of amphibian species worldwide. North america most of the 21 amphibian species in the u. Global declines of amphibians refer to the phenomenon of the population. It is well established that a decrease in genetic variation can lead to reduced fitness and lack of adaptability to a changing environment. Amphibians, a unique group of vertebrates containing over 7,000 known species, are threatened worldwide. Furthermore, we argue that population declines are caused. Amphibian species have experienced population declines and extinctions worldwide that are unprecedented in recent history. Here we use data from 936 populations to assess largescale temporal and spatial variations in amphibian population trends. Population declines involving a large percentage of the amphibian community continue to be documented. Supporting documentation of the 936 amphibian population time series used in quantitative evidence for global amphibian population declines.
Table 1, consistent with previous assessments,17,21, and that similar rates. These may include ultraviolet radiation, predation, habitat modification, environmental acidity and toxicants, diseases, changes in climate or weather patterns, and interactions among these factors. Hatch11department of zoology, 3029 cordley hall, oregon state university. We have advanced our understanding of the amphibian decline problem substantially since the anecdotal reports of scientists in the late 1980s, but continuing research has. Population declines and priorities for amphibian conservation in latin america. From a conceptual perspective, we believe that an ideal. Houlahan j e, findlay c s, schmidt b r, meyer a h and kuzmin s l 2000 quantitative evidence for global amphibian population declines. Ranges of many species have been dramatically reduced and species extinctions have occurred rapidly in some protected areas. Reports of malformed amphibians and global amphibian declines have led to. By contrast, we suggest that studies on individual responses are a crucial part of an integrative approach to understanding multiple stressor impacts on natural populations. Amphibian population declines global declines in amphibian population are. Amphibian fungal panzootic causes catastrophic and ongoing.
The decline of amphibian populations in many sites around the world has focused the interest of many researchers because, in addition to declines due to habitat modification or alien species introduction affecting many living organisms, some instances of populations decline or extinction have occurred without obvious reasons alford and richards, 1999. Literature citations edited by john wilkinson johnjwilkinson at hotmail, may 14, 2008. An increasing number of studies over the last decade have reported declines in amphibian populations in areas of pristine habitat. Thus, we suggest that a single factor for amphibian population declines is highly unlikely. Pdf quantitative evidence for the effects of multiple. Global amphibian declines, loss of genetic diversity and. Houlahan et al examined means of trends for 936 amphibian populations and concluded that global declines began in the late 1950s, peaked in the 1960s, and have. Since the 1980s, decreases in amphibian populations, including population crashes and mass localized extinctions, have been observed in locations all over the world. Amphibians have existed on earth for over 300 million years, yet in just the last two decades there have been an. Blaustein ar, hoffman pd, hokit dg, kiesecker jm, walls sc, hays jb. Houlahan je, findlay cs, schmidt br, meyer ah, kuzmin sl. Lips2,3 department of zoology, southern illinois university, carbondale, illinois 629016501, u. One of the first lines of defense against pathogens that enter by way of the skin are antimicrobial peptides synthesized.
Many of these recent declines have been linked to a pathogenic skin fungus, batrachochytrium dendrobatidis, or to iridoviruses of the genus ranavirus. The decline in amphi bian populations is an ongoing mass extinction of amphibian species worldwide. The geographic extent and severity of amphibian population declines make the subject a conservation issue of high priority. The role of amphibian antimicrobial peptides in protection. Quantitative evidence for global amphibian population. Amphibians as environmental sentinels springerlink. We combined nearly half a million actual observations of 84 species across 61 study areas to answer questions about the causes of widescale amphibian declines. Widespread population declines, extinctions, and impacts1 karen r. On a global scale, our results indicate relatively rapid declines from the late 1950searly 1960s to the late 1960s, followed by a reduced rate. Emerging infectious diseases and amphibian population. The majority of the recent reductions in the earths biodiversity can be attributed to direct human impacts on the environment. N2 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.
We then provide evidence that many amphibian population declines are probably the result of complex interactions among multiple factors. Global declines of amphibians refers to the phenomenon where amphibian species are experiencing severe population declines around the world. Perspectives on amphibian population declines long point. There has been much recent concern about global amphibian population declines. The research, quantitative evidence for the effects of multiple drivers on continentalscale amphibian declines, was led by evan grant, usgs. Declines in population size may be addressed with quantitative, demographic data and. A 2004 global assessment baillie et al eds 2004 found that nearly onethird 32% of the worlds amphibians are threatened, representing 1,856 species. Young be, lips kr, reaser jk, ibanez r, salas aw, cedeno. Quantitative evidence for the effects of multiple drivers on. Since initial recognition of this global problem in the late 1980s wake, 1991.
We discuss recent data on two newly emerging infectious diseases of amphibians and, by reference to hostparasite ecology, propose hypotheses to explain their origin and impact. Moreover, there is some evidence that shortterm changes in weather may affect amphibian population declines. Although known for frogs and salamanders, unequivocal declines have not been documented for caecilians e. For over 20 years amphibian ecologists have generally followed the declining population paradigm 3, conducting research to identify the complex causes underlying declines 4,5,6,7,8, and have. Amphibiaweb maintains a list of recent scientific publications on amphibian declines and amphibian. Quantitative evidence for the effects of multiple drivers. Numerous factors, such as global environmental changes, habitat destruction, introduced species, diseases, and chemical pollution, appear to be contributing to amphibian population declines lannoo 2005. On a global scale, our\ud results indicate relatively rapid declines from the late 1950searly 1960s to the late 1960s, followed by a reduced rate of decline to the present. Amphibian population trends during the 1960s were negative in western europe including the united kingdom and north america, but only the latter populations showed declines. Declines and losses of amphibian populations are a global problem with complex local causes. Bd, the agent of amphibian chytridiomycosis, which has caused population declines globally, is a priority for many land managers.
To summarize current knowledge about the status of declining amphibian populations. We elaborate on the extent of recent fragmentation of amphibian gene pools and we propose the. On a global scale, our results indicate relatively rapid declines from the late 1950searly 1960s to the late 1960s, followed by a reduced rate of decline to the present. Linking global warming to amphibian declines through its. Quantitative evidence for the effects of multiple drivers on continentalscale amphibian declines. Granular gland transcriptomes in stimulated amphibian skin. Quantitative evidence for the effects of multiple drivers on continentalscale amphibian declines article pdf available in scientific reports 6. Declines in biodiversity are occurring across the globe at an alarming rate pimm et al.
Amphibians are among the most affected taxa, with at least 32. Because few dieoffs and population declines of amphibians have ever been observed directly, especially prior to the 1990s, attribution of the causes and the timing of these events is often only a rough estimate, and in many cases, no additional data will ever be available. New research confirms continued, unabated and largescale. Armi new research confirms continued, unabated and large.
Existing largescale analyses of amphibian declines have relied on expert opinion and range maps extrapolated. These declines are known as one of the most critical threats to global biodiversity. Most studies of amphibian declines have focused on identifying causes and documenting changes in adult abundance, rather than on their ecological consequences. Amphibians are declining on a global scale, and we present a fourpoint argument as to why this taxonomic group seems especially prone to such genetic processes. No evidence of general decline in an amphibian community. Quantitative evidence for global amphibian population declines. The chytrid fungus batrachochytrium dendrobatidis was identified in amphibian populations about 20 years ago and has caused death and species extinction at a global scale. Predicting susceptibility to future declines in the world.
A laboratory study in 19801981 in which temperate zone amphibians that were prevented from hibernating had decreased growth rates, matured at a smaller size and had increased. For over 20 years amphibian ecologists have generally followed the declining population paradigm 3, conducting research to identify the complex causes underlying declines 4,5,6,7,8, and have called for the collection of additional data at more locations to further document and. Sorry, we are unable to provide the full text but you may find it at the following locations. However, the mechanisms of its effects remain unclear. We provide strong evidence that the average rate of decline in amphibian metapopulations is 3. Since amphibian declines were first proposed as a global phenomenon. Chytridiomycosis causes amphibian mortality associated with population declines in the rain forests of australia and central america. Terms in this set 27 global basisamphibians are undergoing extreme population declinespopulation crashes were notedmass localized extinctions had occurred. Although weather conditions are more likely to be transient, localized events rather than. Adding to the complexity associated with amphibian population declines are observations that the behavior and life history characteristics of. However, relatively little sampling of amphibian communities has occurred at high latitudes. A recent assessment of the worlds amphibians stuart et al.
Our view is based on both conceptual and practical grounds. There is general consensus that climate change has contributed to the observed decline, and extinction, of many amphibian species throughout the world. Proceedings of the national academy of sciences, usa 95. Amphibian population trends during the 1960s were negative in western europe including the united kingdom and\ud north america, but only the latter populations showed. Pdf houlahan je, findlay cs, schmidt br, meyer ah, kuzmin sl. Uv repair and resistance to solar uvb in amphibian eggs. Amphibian declines diversity and distributions 2003 9, 123140 blackwell science, ltdultraviolet radiation, toxic chemicals and amphibian population declines andrew r. Direct and indirect effects of climate change on amphibian. Amphibian extinction risk and population declines are taxonomically non. Rapid spread of disease is a hazard in our interconnected world.