Taxonomic distinctness and conservation of a new high biodiversity subterranean area in Brazil

Abstract

Subterranean environments, even though they do not possess a primary production (photosynthesis), may present high biodiversity, faunistic originality, endemism, phylogenetic isolations and unique ecological and/or evolution events, in addition to rare taxa. Studies investigating the biological diversity in Neotropical caves are relatively rare and recent, and most of them have been conducted in Brazil. We sampled caves from the state of Bahia, northeastern Brazil, and through sampling sufficiency tests and richness estimators, we demonstrate that the normatization for the Brazilian cave laws is not adequate for its conservation and that only α diversity index is not enough to verify faunistic patterns. We suggest that a phylogenetic diversity index be more robust and accurate for conservation purposes, particularly the Taxonomic Distinctness index. Moreover, we propose that the sandstone complex caves from Chapada Diamantina National Park need to be classified as being of high subterranean biodiversity in a global scope.

Terrestrial fauna of the largest granitic cave from Southern Hemisphere, southeastern Brazil: A neglected habitat

“…It is mandatory a robust sampling effort with standardized replicas to describe the taxonomic diversity and understand the community functioning (Trajano, 2013;Gallão and Bichuette, 2015). This affirmation is corroborated by estimators values observed at Figure 7, allied to the intermediary values of singletons and doubletons, which represent the occurrence of only one (single) or two (double) individuals in all samplings.…”

“…It is noteworthy that in these studies it was necessary at least four sampling occasions to reach that richness of opilionids and other species records, which indicates that the number of samplings is directed related to the diversity. Gallão and Bichuette (2015) show that even after six sampling occasions, species were added in their samplings, which highlights the inefficiency of Brazilian laws that demand only two sampling occasions (Trajano, 2010;Gallão and Bichuette, 2015). Besides, the high richness of opilionids in Riacho Subterrâneo cave likely is related to vegetation surrounding, which is remaining of Atlantic Rainforest.…”

“…This affirmation is corroborated by estimators values observed at Figure 7, allied to the intermediary values of singletons and doubletons, which represent the occurrence of only one (single) or two (double) individuals in all samplings. Gallão and Bichuette (2015) and Bichuette et al (2015), studying sandstone and limestone caves, respectively, stressed this question and proposed the necessity of replicas on subterranean studies to discuss any distribution and diversity pattern, since they are related to intrinsic temporal variations (Trajano, 2013). The spatial and temporal distribution of cave fauna is influenced by several factors which presents variation in their occurrence, such as patches of vegetable organic matter, guano, concentration of prey (Trajano, 2013), allied to the desiccation of surface habitats in climatic marked regions (in this case, cave habitats operate as seasonal shelters).…”

The first two hotspots of subterranean biodiversity in South America

“…Systematic inventories in the presented caves (AS and TG) have revealed a high diversity of troglobitic species and good potential to discover new species. However, in the studies performed to date on the fauna from more than 2,000 Brazilian caves with approximately 800 troglomorphic/troglobitic species, only the Areias and Toca do Gonçalo systems occupy a prominent position in relation to the number of stygobiotic and troglobitic species (Trajano and Bichuette 2010, Cordeiro et al 2014, Gallão and Bichuette 2015. In addition, TG stands out with 22 troglobitic species found in both terrestrial and aquatic habitats because of its reduced extension and depth (Table 3).…”

“…The great majority of these recent studies has been developed in Brazil, where the highest proportions of karstic landscapes of South America occur in different rock types (Souza-Silva et al 2011, CEBS-UFLA 2015, Cordeiro et al 2014, Gallão and Bichuette 2015.…”