Climate crisis: Sandy soil reptiles could become extinct – 03/14/2024 – Environment

Reptiles that live in sandy soils in dry areas have already been identified as beneficiaries of rising temperatures in the coming decades, due to the supposed expansion of areas suitable for life and because they already tolerate high temperatures.

A study published in the Journal of Arid Environments by Brazilian researchers shows, however, that the scenario could be very different.

“We observed that climate change will alter the geographic distribution of reptiles and cause the extinction of some species, the opposite of what was thought”, summarizes Júlia Oliveira, first author of the work, carried out as part of her master’s degree at Uema (Universidade Estadual do Maranhão).

The study is part of the project “Evolution and Biogeography of Herpetofauna: patterns, processes and implications for conservation in a scenario of environmental and climate change”, coordinated by Thaís Guedes, professor at IB-Unicamp (Institute of Biology at the State University of Campinas) and Oliveira’s advisor.

“The species studied have the peculiarity of being adapted to areas with sandy soil, which gave them characteristics such as reduced or absent legs, reduced eyes and raised scales on the tip of the head, body adaptations to live in this type of environment. Therefore, The suitable area for the life of these species, in the present and in the future, also depends on specific soil conditions”, explains Guedes.

The study considered occurrence records of ten species adapted to sandy soils (psammophiles) present in the so-called Diagonal de Formações Abertas or Diagonal Seca. These are two of the terms used to define the corridor of dry forests that crosses South America, from the Argentine and Paraguayan Chaco, passing through the Cerrado to the Caatinga.

Five species of lizards and five of snakes were analyzed. Based on the species occurrence information, data on the current climate, soil type and other variables that allow these animals to survive were added.

Subsequently, simulations were made of how these locations would be in optimistic and pessimistic scenarios of greenhouse gas concentrations for 2040 and 2060. These scenarios are designed by the IPCC (Intergovernmental Panel on Climate Change) of the UN (United Nations).

The models also pointed out suitable regions for species where field studies have not yet been carried out to verify the presence of these animals.

According to the researchers, these are priority areas for future prospecting, such as the dunes of São Francisco, in Bahia, and patches of sandy soil in the caatinga of Piauí, which have proven to be highly suitable for housing even endemic species (which only exist there).

Extinction and loss of areas

Even in the optimistic scenario for 2040, with moderate levels of emissions, all ten species analyzed lose suitable areas, exceeding gains in terrain and climate. The blue-tailed lizard (Microblepharus maximiliani) and the red-tailed lizard (Vanzosaura savanicola) would have the greatest area loss (88% and 99%, respectively), which means extinction for the latter.

The prospects do not improve much for the year 2060, still in an optimistic climate change scenario. In it, all species analyzed lose their home range, from 2.5% to 100%. The red-tailed lizard and snakes known by names such as false coral (Rodriguesophis iglesiasi) and rapids snake (Phalotris matogrossensis).

Two other lizards and a snake had predicted area losses of between 60% and 82%.

The pessimistic climate scenario for 2040 also predicts more losses than gains of suitable areas for all species, with two species predicted to suffer area losses of over 76%.

The perspective is similar when considering high emissions in 2060, with even more significant losses. Although the expected gains will be greater for some species than in other scenarios, the losses will be even greater, including with extinctions such as the red-tailed stingray (Vanzosaura rubricauda).

For researchers, the results are extremely worrying, even more so because this type of threat has been neglected for reptiles that live buried in sandy soil.

The authors note that the most recent assessment of the threat of extinction of reptiles by ICMBio (Instituto Chico Mendes de Conservação da Biodiversidade), which defines the degree of threat to species at a national level, is from 2022, and still does not consider climate change as a a threat factor.

The guidelines are the same as those of the IUCN (International Union for Conservation of Nature), a global reference body for this type of analysis.

“Based on the criteria currently considered when assessing the degree of threat, some of the species that we are predicting major losses, and even extinction, would not even be threatened. This needs to change in the next assessment”, argues Oliveira.

One of the measures to avoid, or at least mitigate the announced catastrophe, would be to create new full protection conservation units, or expand existing ones in an optimized way, in places suitable for these species in the present and in the future.

Compared to the territorial extension of Diagonal Seca, the protected areas in these biomes are tiny, corresponding to less than 2% of the caatinga, 10% of the cerrado and 9% of the chaco.

“Our study demonstrates that future climate conditions may reduce the effectiveness of current conservation units in protecting the diversity of these reptiles”, says Guedes.

This is because, although 27 protected areas have been created in the last six years in Diagonal Seca, less than 16% of the total conservation units in the cerrado and caatinga are suitable for the occurrence of these lizards and snakes in future climate scenarios.

With this, the authors conclude that something similar to what has already been predicted for birds, plants and mammals of the caatinga could happen to reptiles on sandy soil.

Studies by other researchers have already shown that for these groups, a homogenization of species is most likely to occur, with a few generalists replacing the rare ones and specialists.

“An optimistic message from this study is that there is still potential to discover new areas of occurrence of reptile species adapted to living in sandy soil. But the main warning is that, on a changing planet, future climate scenarios urgently need to be incorporated into planning of conservation”, concludes Guedes.

The work was supported by Fapesp through a post-doctoral scholarship for Karoline Ceron.

The article in English is available at this link.