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