Catastrophic Population Declines and Extinctions in Neotropical Harlequin Frogs (Bufonidae: Atelopus)¹

Abstract

We surveyed the population status of the Neotropical toad genus Atelopus, and document recent catastrophic declines that are more severe than previously reported for any amphibian genus. Of 113 species that have been described or are candidates for description, data indicate that in 42 species, population sizes have been reduced by at least half and only ten species have stable populations. The status of the remaining taxa is unknown. At least 30 species have been missing from all known localities for at least 8 yr and are feared extinct. Most of these species were last seen between 1984 and 1996. All species restricted to elevations of above 1000 m have declined and 75 percent have disappeared, while 58 percent of lowland species have declined and 38 percent have disappeared. Habitat loss was not related to declines once we controlled for the effects of elevation. In fact, 22 species that occur in protected areas have disappeared. The fungal disease Batrachochytrium dendrobatidis has been documented from nine species that have declined, and may explain declines in higher elevation species that occur in undisturbed habitats. Climate change may also play a role, but other potential factors such as environmental contamination, trade, and introduced species are unlikely to have affected more than a handful of species. Widespread declines and extinctions in Atelopus may reflect population changes in other Neotropical amphibians that are more difficult to survey, and the loss of this trophic group may have cascading effects on other species in tropical ecosystems. RESUMENExaminamos el estado poblacional de las ranas neotropicales del género Atelopus y documentamos disminuciones catastróficas recientes, las más drásticas señaladas para cualquier género de anfibios. De las 113 especies que han sido descritas o son candidatas para ser descritas, los datos poblacionales indican que en 42 especies, las poblaciones han sido reducidas por lo menos a la mitad y solamente diez especies tienen poblaciones estables. El estado de los taxa restantes es desconocido. Por lo menos 30 especies no han sido vistas en al menos ocho años de todas las localidades conocidas, y se teme que se hayan extinguido La mayoría de estas especies desaparecieron entre 1984 y 1996. Todas las especies con SPECIAL SECTION Declines and Extinctions of Atelopus 191rangos altitudinales de 1000 m o superiores han sufrido disminuciones poblacionales, el 75 por ciento de estas ha desaparecido del todo. El 58 por ciento de las especies de bajura han sufrido disminuciones, mientras que el 38 por ciento ha desaparecido del todo. La pérdida de hábitat, no fue relacionada con las disminuciones una vez que se controló el efecto de altura en los análisis. De hecho, unas 22 especies que tienen poblaciones dentro deáreas protegidas han desaparecido. El hongo quítrido Batrachochytrium dendrobatidis estuvo presente en nueve especies que han experimentado disminuciones y puede explicar desapariciones en especies que ocupan hábitats no perturbados a mayores elevac...

Diversity, natural history and conservation of amphibians and reptiles from the San Vito Region, southwestern Costa Rica

“…It has been speculated that this species has experienced several local extinctions across its geographic range and thus it has been recently classified as critically endangered (IUCN, 2006). The main cause for declines in this severely impacted genus is thought to be the presence of the emerging infectious disease Chytriomycosis driven by global warming (La Marca et al 2005, Pounds, et al 2006. Other species of amphibians that may be declining in the region are Ollotis conifera and Lithobates warszchewitschii, both species were previously observed as abundant, but only rarely recorded in this study.…”

Linking global climate and temperature variability to widespread amphibian declines putatively caused by disease

“…Genus Atelopus is endemic to Costa Rica, Panama, Colombia, Ecuador, Peru, Bolivia, Venezuela, Suriname, Guyana, Brazil, and French Guiana and, since 1980, 67 of 108 extant "species" have ostensibly gone extinct (20). Of these 108 extant species, 32 are undescribed (20). The second dataset, described by Lips et al (17), is the year that each of 59 species (all described) in genera Atelopus and Telmatobius (4 species found in Ecuador and Peru) began to decline [year of decline (YOD)].…”

“…The first dataset, compiled by La Marca et al (20), is the year (between 1980 and 1998) that each "species" in the frog genus Atelopus was observed for the last time [last year observed (LYO)], presumably owing to the species going extinct or at least undergoing a dramatic decline. Genus Atelopus is endemic to Costa Rica, Panama, Colombia, Ecuador, Peru, Bolivia, Venezuela, Suriname, Guyana, Brazil, and French Guiana and, since 1980, 67 of 108 extant "species" have ostensibly gone extinct (20). Of these 108 extant species, 32 are undescribed (20).…”

Fatal Chytridiomycosis in the Tyrrhenian Painted Frog

“…The emergence of Batrachochytrium dendrobatidis (Bd), the etiological agent of chytridiomycosis, is responsible for regional mass mortality events of amphibian hosts, as well as host population declines and extinctions (Lips et al, 2008;Schloegel et al, 2006;La Marca et al, 2005;Laurance et al, 1996). These regional effects are detectable at broad geographic scales: the pathogen occurs on six continents, infects hundreds of amphibian species, and is widely recognized as a major contributor to the global decline of amphibians Lips et al, 2008).…”

“…The amphibian fauna of Sardinia is unique: of the nine native amphibian species, six are endemic, and another two have extremely restricted ranges limited to Sardinia, Corsica, and nearby islands. Both small range size and island endemicity may increase extinction risk Pimm, 1991), and many of the species driven to extinction by chytridiomycosis were known from restricted ranges (La Marca et al, 2005;Schloegel et al, 2006). Six of Sardinia's amphibians are listed as ''Near Threatened,'' ''Vulnerable,'' or ''Endangered'' by the IUCN (http://www.globalamphibians.org/).…”