Climate changes are expected to impact Atlantic Forest amphibian species

Researchers estimate that up to 12% of the biome’s 431 amphibian species may become extinct in the coming decades.

By Elton Alisson

Agência FAPESP – The number of amphibian species and the population sizes of these animals in the Atlantic Forest are expected to decrease substantially as a result of climate changes predicted to occur in the biome in the coming decades.

The estimates come from a study conducted by researchers at the Conservation Biogeography Laboratory at the Federal University of Goiás (UFG), published in the February issue of the journal Biodiversity and Conservation.

Several of the research findings were presented during the workshop “Dimensions US-BIOTA São Paulo – a multidisciplinary framework for biodiversity prediction in the Brazilian Atlantic Forest Hotspot,” held on 10 February at FAPESP under the scope of the research program “Dimensions US-BIOTA São Paulo: a multidisciplinary framework for biodiversity prediction in the Brazilian Atlantic forest hotspot”.

The project brings together scientists from Brazil, the United States and Australia and is being undertaken under the scope of the scientific cooperation agreement between the Research Program in Characterization, Conservation, Restoration and Sustainable Use of the Biodiversity of the state of São Paulo (BIOTA-FAPESP) and the Dimensions of Biodiversity program of the National Science Foundation (NSF), a prominent US federal research-sponsoring agency.

“The projections we made indicate that, because of the climate changes that are expected to occur in the Atlantic Forest in the coming decades, most of the biome’s conservation units will lose and few will gain species of amphibians,” said Rafael Loyola, coordinator of the Conservation Biogeography Laboratory at UFG and one of the authors of the study.

“Apparently, this pattern will also prevail for other species, such as mammals, birds, butterflies and plants,” the researcher noted during his presentation.

According to Loyola, there are 431 species of amphibians in the Atlantic Forest – a biome that holds 18% of all species of these animals in South America. The use of six different distribution models in which the presence of a particular species was associated with a set of environmental variables, such as annual average temperature and precipitation, allowed the researchers to estimate how these 431 species are currently distributed throughout the conservation units in the Atlantic Forest.

Based on four distinct climate change simulations for South America through the year 2050 that were used in the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the researchers estimated the distributions of these species of amphibians in protected areas of the Atlantic Forest. The estimates considered the size, shape and geographic position of the forest reserves and the dispersal ability of the animals along a radius of 50, 100 and 200 kilometers over the next 30 years.

The projections indicated that the locations that are climatically suitable for the survival of amphibians in the Atlantic Forest are expected to diminish by 2050. Therefore, up to 12% of the species of amphibians, located primarily in the northern and southwestern parts of the biome, are expected to become extinct, and 88% will experience population decreases.

“This means that this 12% of the amphibian species will undergo a contraction in population of such magnitude that they will disappear from the biome,” said Loyola. “They are not species that will leave the Atlantic Forest to go to the Cerrado or the Caatinga. They may disappear entirely,” he emphasized.

Changes in phylogenetic structure

In another study, published in the January issue of the journal Ecography, the researchers examined whether climate changes could also alter the evolutionary relationship between species of amphibians that occur in conservation units of the Atlantic Forest. Based on this examination, they determined whether these animals would respond to these alterations as clades (groups that share one exclusive common ancestor) or as isolated species.

The results of the models indicated that older groups (basal clades) of amphibian species such as caecilians or “blind snakes” of the order Gymnophiona and the tongueless frogs of the family Pipidae would be positively affected by climate change and are expected to expand their geographic distribution throughout the Atlantic Forest.

However, more recent groups (derivative clades) of amphibians, such as glass frogs of the family Centrolenidae along with other species of tree frogs, are expected to be severely impacted, and their geographic distribution in the biome may be reduced by up to 90%.

“In some protected areas of the Atlantic Forest, the phylogenetic diversity of the amphibians may increase as a result of the extinction of very recent species, which will cause the basal species to increase their distribution in the biome,” explained Loyola.

“In this case, the phylogenetic diversity will increase for the wrong reason: the loss of very recent species,” he added. One of the amphibian species that is expected to benefit from climate changes, according to the researcher, is the American bullfrog (Lithobates catesbeianus). Introduced to South America in 1930, it is considered an invasive species in Brazil.

“A good number of Atlantic Forest conservation units will become climatically more suitable for this species of amphibian,” said Loyola. “We need to study how it will be possible to avoid or control the invasion of this species to prevent ecological disequilibrium in the biome,” he said.

Contributions of the projections

According to Loyola, the projected changes in the geographic distribution of animal species may help in the planning and implementation of the biome’s conservation measures.

In predicting where the animals should migrate because of the climate changes, he explained that it is possible to map dispersal corridors composed of connected areas that are able to serve as refuge to these animals.

In addition, the projections are also helping to identify areas of the biome in which to establish new conservation units to diminish the effects that climate changes have on the number and composition of the species.

“The models allow the creation of conservation solutions that consider which locations are more suitable for protection in the Atlantic Forest, taking into account the fact that climate will change and that the species will respond to these climate changes in a predictable manner,” he said.

In the study published in Biodiversity and Conservation, the researchers determined that the few reserves in the Atlantic Forest that will gain species in the coming decades are situated in the mountains and have the capacity to maintain a suitable climate for the amphibians.

Based on this determination, they suggest that the new conservation units be established in high-altitude areas of the biome and that dispersal corridors to these locations be created. Accordingly, they can hope to mitigate the effects that climate change will have on the amphibians that are more susceptible to changes in the climate because of their dependence on microenvironments, hydrological regimes and limited dispersal capacity.

“It’s quite possible that this alarming situation could be turned around if the solutions that the scientists have been offering are discussed and implemented by decision makers and lawmakers; this is very good news for the community in general,” Loyola posited.

The article “Climate change threatens protected areas of the Atlantic Forest” (doi: 10.1007/s10531-013-0605-2) by Loyola and colleagues may be viewed in Biodiversity and Conservation at link.springer.com/article/10.1007%2Fs10531-013-0605-2#.

The article “Clade-specific consequences of climate change to amphibians in Atlantic Forest protected areas” (DOI: 10.1111/j.1600-0587.2013.00396.x), also by Loyola and colleagues, may be viewed in Ecography in onlinelibrary.wiley.com/doi/10.1111/j.1600-0587.2013.00396.x/abstract.