Conservação dos Quelônios Continentais no Brasil

Abstract

Field surveys are highly necessary for obtaining a consistent knowledge about the geographic range of all the 31 Brazilian Chelonian species. Currently, only for the Brazilian Amazon, which harbors 18 species, this knowledge is satisfactorily gathered. The Brazilian biomes Caatinga, Cerrado, and Pantanal are of great importance for our Open Formation Diagonal (DFAB, in Portuguese), in which a rich biodiversity develops, with biodiversity well-adapted to pronounced rainy seasons. Still, very few information on the Chelonian species occurring in the DFAB is available. From the literature, scientific collections, records banks and unpublished data, we collected records of 19 native species in DFAB (Kinosternon scorpioides1, Trachemys adiutrix2, Rhinoclemmys punctularia3, Chelonoidis carbonarius4, C. denticulatus5, Acanthochelys macrocephala6, A. spixii7, Chelus fimbriata8, Hydromedusa maximiliani9, H. tectifera10, Mesoclemmys gibba11, M. perplexa12, M. tuberculata13, M. vanderhaegei14, Phrynops geoffroanus15, P. tuberosus16, Platemys platycephala17, Podocnemis expansa18 e P. unifilis19). All the above cited species occur in Cerrado; 10 in Caatinga (1-2-4-5-9-11-12-13-15-16) and six in Pantanal (1-4-5-6-14-15). These represent about 60% of all continental chelonian species in Brazil; three of them are considered endemic for DFAB (2-6-12). In addition, we constructed a consensus model between some algorithms, like Maxent, Support Vector Machine and Random Forest, and 19 bioclimatic variables, and also 3 topographic variables. The prioritization was performed by using the "additive benefit" parameter of the Zonation software, which selects Systematic Planning Units (ottobacias 4) with high number of targets. These results corroborate studies with other vertebrates, with a high number of species, but, on the other hand, with a low degree of biological distinction. The geographic location of the DFAB, combined with the hydrographic connectivity between the Chaco, the Amazon and the Atlantic Forest, certainly justifies such results. We also prioritized at least 10% of the distribution of each species, which corresponded to 25.6% of DFAB (16.7% in Cerrado, 6.6% in Caatinga, and 2.2% in the Pantanal). This percentage is related to the number of species in each biogeographic unit. It is also related to some factors such as the condition of the landscape and the high similarity of species between the Amazon and the Atlantic Forest, resulting in the prioritization of areas mainly in the margin of the DFAB. Keywords: Testudines, inventories of fauna, systematic conservation planning, species distribution modelling.