GW may drive 10 per­cent of am­phib­ian species in the At­lantic Rain­for­est to ex­tinc­tion

Tehran Times - - SCIENCE -

Global warm­ing (GW) could lead to the ex­tinc­tion of up to 10% of frog and toad species en­demic to Brazil’s At­lantic Rain­for­est biome within about the next 50 years. The tem­per­a­ture and pre­cip­i­ta­tion regimes pre­dicted to oc­cur be­tween 2050 and 2070 will be lethal for species that are less well adapted to cli­mate vari­a­tion and in­habit cer­tain ar­eas of the At­lantic Rain­for­est.

This is one of the find­ings of a study that an­a­lyzes the present and fu­ture dis­tri­bu­tion of anu­rans (tail­less am­phib­ians, i.e., frogs and toads) in Brazil’s At­lantic Rain­for­est and Cer­rado (sa­vanna) biomes in the con­text of cli­mate change due to con­tin­u­ous global warm­ing.

A pa­per on the study has been pub­lished in the jour­nal Ecol­ogy and Evo­lu­tion. The first au­thor is her­petol­o­gist Ti­ago da Sil­veira Vas­con­ce­los, a re­searcher at São Paulo State Univer­sity’s School of Sciences (FC-UNESP) in Bauru, Brazil.

At present, 550 anu­ran species are known to in­habit the At­lantic Rain­for­est (80% of them en­demic), and 209 are known to be present in the Cer­rado. Af­ter re­mov­ing species with fewer than five oc­cur­rence records, Vas­con­ce­los worked with spa­tial dis­tri­bu­tion data for 350 species in the At­lantic Rain­for­est and 155 species in the Cer­rado.

“In this man­ner, we were able to iden­tify the At­lantic Rain­for­est and Cer­rado ar­eas with the high­est lev­els of anu­ran species rich­ness and with unique species com­po­si­tion,” Vas­con­ce­los said. “Hav­ing iden­ti­fied th­ese ar­eas, we eval­u­ated the anu­ran com­mu­ni­ties in cur­rent and fu­ture cli­mate sce­nar­ios in or­der to de­ter­mine which ar­eas of­fered a fa­vor­able cli­mate for each of the 505 species an­a­lyzed and whether the ar­eas would ex­pand or con­tract by 2050 and 2070 ow­ing to global warm­ing.”

Im­pact of cli­mate change

The “first ex­pected im­pact of cli­mate change on anu­ran am­phib­ians in the At­lantic Rain­for­est and Cer­rado is the ex­tinc­tion of 42 species due to the com­plete loss of the ar­eas with fa­vor­able cli­mate con­di­tions be­tween 2050 and 2070,” Vas­con­ce­los said.

From the 42 species likely to be ex­tinct,

37 of them are At­lantic Rain­for­est species

(10.6% of the to­tal) and five are Cer­rado species. Of th­ese 42 species, only five are cur­rently con­sid­ered en­dan­gered by Brazil’s En­vi­ron­ment Min­istry.

The spa­tial dis­tri­bu­tion data for 350 At­lantic Rain­for­est species and 155 Cer­rado species were an­a­lyzed in terms of two com­mu­nity ecol­ogy met­rics: al­pha diver­sity, de­fined as lo­cal species rich­ness within a spe­cific habi­tat or ecosys­tem, and beta diver­sity, a mea­sure of struc­tural het­ero­gene­ity based on the ex­tent to which species com­po­si­tion varies as a func­tion of dis­tance.

Ac­cord­ing to Vas­con­ce­los, the next step was to gen­er­ate eco­log­i­cal niche mod­els based on the cli­mate char­ac­ter­is­tics fa­vor­able to each species, us­ing four al­go­rithms: gen­er­al­ized lin­ear mod­els, boosted re­gres­sion trees, ran­dom forests, and sup­port vec­tor ma­chines.

The al­go­rithms gen­er­ated maps of the At­lantic Rain­for­est and Cer­rado ar­eas in which each species can sur­vive thanks to their sim­i­lar cli­mates. They were then cal­i­brated with fu­ture cli­mate sce­nar­ios based on pro­jec­tions avail­able from the WorldClim global cli­mate data­base.

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