In an article published in the journal Ecology and Evolution, researchers affiliated with institutions in Brazil and Paraguay report the results of a study according to which the distribution of snake species in the Chaco correlates closely with the adaptations that have occurred during their evolution.
"In the south, which is drier, most species are fossorial [living primarily underground], while in the north, which is influenced by the Amazon and other rainforests, snakes are mainly arboreal [tree dwellers]. The differences are evidenced by their morphology [body shapes]," said Hugo Cabral, first author of the article. Cabral, a Paraguayan-born researcher, conducted the study as a Ph.D. candidate at São Paulo State University's Institute of Biosciences, Letters and Exact Sciences (IBILCE-UNESP) in São José do Rio Preto (Brazil).
The study showed that most species in the northern portion of the Chaco ecoregion tend to have long tails, which can correspond to almost half their total length. This means they are arboreal or semi-arboreal, with prehensile tails that can grip tree branches or other objects.
Nearer the Amazon, the Andean Forest and Chiquitania, a region of tropical savanna in eastern Bolivia, the northernmost part of the Chaco is also wetter, with considerable diversity of tree species that are home to snakes that have adapted to live above ground.
In the southern part, species are shorter overall with shorter tails and have small eyes, all of…