Conserving Biogeography: Habitat Loss and Vicariant Patterns in Endemic Squamates of the Cerrado Hotspot

Abstract

Little is known about the threat levels and impacts of habitat loss over the Cerrado Squamate fauna. The region is under severe habitat loss due to mechanized agriculture, accelerated by changes in the Brazilian National Forest Code. The Squamate fauna of the Cerrado is rich in endemics and is intrinsically associated with its surrounding microhabitats, which make up a mosaic of phitophysiognomies throughout the region. Herein we evaluate current conservation status of Squamate biogeographic patterns in the Brazilian Cerrado, the single savanna among global biodiversity hotspots. To do so, we first updated point locality data on 49 endemic Squamates pertaining to seven non-random clusters of species ranges in the Cerrado. Each cluster was assumed to be representative of different biogeographic regions, holding its own set of species, herein mapped according to their extent of occurrence (EOO). We then contrasted these data in four different scenarios, according to the presence or absence of habitat loss and the presence or absence of the current protected area (PA) cover. We searched for non-random patterns of habitat loss and PA coverage among these biogeographic regions throughout the Cerrado. Finally, with the species EOO as biodiversity layers, we used Zonation to discuss contemporary PA distribution, as well as to highlight current priority areas for conservation within the Cerrado. We ran Zonation under all four conservation scenarios mentioned above. We observed that habitat loss and PA coverage significantly differed between biogeographic regions. The southernmost biogeographic region is the least protected and the most impacted, with priority areas highly scattered in small, disjunct fragments. The northernmost biogeographic region (Tocantins-Serra Geral) is the most protected and least impacted, showing extensive priority areas in all Zonation scenarios. Therefore, current and past deforestation trends are severely threatening biogeographic patterns in the Cerrado. Moreover, PA distribution is spatially biased, and does not represent biogeographic divisions of the Cerrado. Consequently, we show that biogeographic patterns and processes are being erased at an accelerated pace, reinforcing the urgent need to create new reserves and to avoid the loss of the last remaining fragments of once continuous biogeographic regions. These actions are fundamental and urgent for conserving biogeographic and evolutionary information in this highly imperiled savanna hotspot.

Structure and regional representativeness of the herpetofauna from Parque Estadual da Serra de Caldas Novas, Cerrado, Central Brazil

“…The reptile communities of the PESCAN includes seven endemic species (21.88%) and some "uncommon" species that occur in few PAs, as the snakes Bothrops pauloensis, Erythrolamprus almadensis, Rhachidelus brazili, and A. brongersmianus and the chelonian Mesoclemmys vanderhaegei. These results reinforces that studies with significant sampling efforts, both in PAs and in unprotected forest fragments, need to be performed to better understand the population status of most snake species [14,80]. Regarding the chelonian M. vanderhaegei, although it occurs in open and altered habitats (rivers, lakes, low-order streams, oligotrophic streams, ponds with aquatic vegetation, and artificial dams), the lack of information on the natural history, and intensive destruction and degradation of their natural habitats justify its inclusion into the category "Lower Risk/Near Threatened" according to the IUCN criteria [55].…”

“…Knowledge about the biological diversity in PAs is extremely important for the quantification of species, populations, and communities in PAs and to understand the true species conservation status in order to develop preservation strategies [24,28,74]. It is also necessary to assess situations and trends of anuran and reptile populations in areas outside of PAs, such as legal reserves on private property, since PAs do not accommodate all species in biogeographical terms [80]. The maintenance of natural vegetation fragments through legal reserves would be an alternative to maintain populations of restricted endemic species, allowing the dispersal of species between preserved and unpreserved areas through ecological corridors [75,80].…”

“…It is also necessary to assess situations and trends of anuran and reptile populations in areas outside of PAs, such as legal reserves on private property, since PAs do not accommodate all species in biogeographical terms [80]. The maintenance of natural vegetation fragments through legal reserves would be an alternative to maintain populations of restricted endemic species, allowing the dispersal of species between preserved and unpreserved areas through ecological corridors [75,80]. Since many areas have not been sampled, it is essential to conduct other studies to know which species are present in the PAs as this enables the development of new conservation strategies, involving the choice of areas that have species not yet registered in PAs.…”

Museums and cradles of diversity are geographically coincident for narrowly distributed Neotropical snakes

“…Topography and certain climate-related characteristics are responsible for the maintenance of both ancient and recent diversity. The areas of high PE found here add conservation value to the already recognized centres of high species richness for snakes in the Neotropics, such as Amazonia (Guedes et al 2018), and those undergoing extreme habitat loss, such as the Cerrado savannas (de Mello et al 2015). Some areas already identified as biodiversity hotspots, such as the Atlantic Forest (Myers et al 2000), are also recovered as centres of mixedendemism and, therefore, of high conservation value both for their current diversity patterns and for their respective underlying evolutionary and ecological potential (Crandall et al 2000).…”

Delimiting floristic biogeographic districts in the Cerrado and assessing their conservation status

“…Several studies have been conducted to identify conservation priority areas in the Cerrado. These have used different approaches, such as the distribution of endemic species (Simon and Proença 2000;Silva and Bates 2002;Diniz-Filho et al 2008;Nogueira et al 2011;Carmignotto et al 2012;Azevedo et al 2016), the identification of vicariant processes (de Mello et al 2015), macroecology (Diniz-Filho et al 2008 or species community composition (Ratter and Dargie 1992;Ratter et al 1996Ratter et al , 2003Aguiar et al 2015;Amaral et al 2017). The Cerrado biome harbours three to five main areas of endemism, depending on the studied group.…”