Priorities for Conservation of the Evolutionary History of Amphibians in the Cerrado
Débora Leite Silvano, Paula Hanna Valdujo, and Guarino Rinaldi Colli
Abstract Population declines and species extinction can be abated through the establishment of effective conservation policies. Actions and policies towards biodiversity conservation must be well planned and priorities must be set. Besides the widely recognized principles of systematic conservation planning, it is also important to consider species attributes, such as their evolutionary distinctiveness (ED) and distribution pattern. In this study we did a gap analysis to evaluate protection status of anuran species endemic to the Brazilian Cerrado. We then selected priority areas for conservation in this biome based on a systematic conservation planning framework, also including species attributes as prioritization criteria. We found 65 gap species, for which less than 20 % of their conservation targets are met by the current network of protected areas, and 39 of them are not protected at all. Priority areas are located in the central portion of the Cerrado, and include river valleys and mountaintops. Mountains in southeastern and central Cerrado are especially rich in endemic and range-restricted species, resulting in higher priority values for these areas. Priority areas selected here are also the richest regions and have greater Total Evolutionary Distinctiveness than the rest of the biome, demonstrating their high potential for conserving evolutionary history of anuran lineages in the Cerrado. Despite their great importance for biodiversity, areas that have higher richness of endemic species are also those that suffered from more severe loss of habitat, which reinforces the urgency for effective actions towards species conservation.
Keywords Evolutionary distinctiveness • Systematic conservation planning • Gap analysis • Marxan • Brazil
Declines and extinctions of species often occur simply because many countries do not have an effective conservation policy. These declines are creating a demand for rapid and urgent strategies to maximize conservation efforts, especially in regions where there is little data on diversity, abundance and distribution of species, such as in Brazil (Young et al. 2001). Amphibians are perhaps the most threatened group of organisms at global scale (Wake and Vredenburg 2008; see Youssefou and Davies chapter “Reconsidering the Loss of Evolutionary History: How Does Non-random Extinction Prune the Tree-of-Life?”), with rapidly declining populations throughout the world (Stuart et al. 2004; Becker et al. 2007) and a significant concentration in the Neotropics (Becker and Loyola 2008). Brazil is the world leader in amphibian diversity. In spite of that, there is not yet a specific agenda for their conservation. There are some important initiatives undertaken by the government, such as lists of endangered species and the selection of priority areas for conservation (Silvano and Segalla 2005). However, these initiatives are quite general and often use subjective criteria.
Other initiatives are being conducted by the academic community, such as the Action Plan for Amphibian Conservation in Brazil (Verdade et al. 2012). Among the proposals outlined in this Action Plan for Amphibian Conservation, there is an indication of priority areas for their conservation (Verdade et al. 2012). To make this effective, it is recommended that they follow the same principles of systematic conservation planning (SCP) (Margules and Pressey 2000). SCP aims at a cost efficient protected areas network with the help of purposely built computer software that takes advantage of optimization algorithms. These criteria are essential to define the smallest set of areas necessary to achieve preset conservation goals (see Arponen and Zupan chapter “Representing Hotspots of Evolutionary History in Systematic Conservation Planning for European Mammals”). Since there are no resources neither enough time to conserve species one by one, we need to maximize the return on investment in conservation (Margules and Pressey 2000).
For conservation to be effective, in addition to the basic principles related to systematic conservation planning, it is necessary to consider certain attributes of the target species. Among these characteristics, we highlight Evolutionary Distinctiveness (ED) (Isaac et al. 2007) and their range size. The ED and range size should be considered independently for each species. The ED is a measure of species' relative contributions to the total diversity in a phylogenetic tree (Isaac et al. 2007). In this framework more relictual species (i.e. those that belong to ancient clades, with few species) should be prioritized by the unique evolutionary history they represent (Posadas et al. 2001). Similarly, species that have restricted distribution (e.g. endemic to Espinhaço range) require further attention over those widely distributed, since the species' range size is the most important predictor for the risk of extinction (Purvis et al. 2000a, b). This approach allows for preserving evolutionary history within a taxonomic group, providing more alternatives for responding to possible future environmental changes (Vazquez and Gittleman 1998; Avise 2005; Becker et al. 2010, and see Faith chapter “The PD Phylogenetic Diversity Framework: Linking Evolutionary History to Feature Diversity for Biodiversity Conservation”).
Since half of the over 200 anuran species that occur in the Cerrado are endemic to this domain (Valdujo et al. 2012), it is critical that conservation strategies are outlined specifically to this region. Cerrado is one of 34 priority areas for conservation on the planet (Biodiversity Hotspots – Mittermeier et al. 2004), due to high levels of endemism of fauna and flora and the high rates of habitat destruction. However, few conservation actions are being carried out there. Currently, less than 2 % of the Cerrado range is under strict protection (CNUC 2010). This percentage is low for a region with high heterogeneity of vegetation and topography, and because the main threat to amphibian conservation in the Cerrado is the destruction of their habitats due to deforestation, expansion of agriculture, mining, fire and infrastructure development (Silvano and Segalla 2005). Therefore, strengthening and expanding the network of protected areas should be prioritized as an important conservation strategy, which could maximize the return on investment in conservation (Margules and Pressey 2000).
In spite of the recognized importance of including information on historical and evolutionary studies to define conservation priorities, in the Cerrado, just few and recent papers consider this information (e.g. Carvalho et al. 2010). The papers published over the last decade involving the prioritization of areas for anurans conservation in the Cerrado were based just on the species' extent of occurrence and richness, in a complementarity approach (e.g. Diniz-Filho et al. 2004, 2007, 2009). In order to contribute to enlarge this perspective, we conducted a gap analysis to check the conservation status of amphibian species endemic to the Cerrado and performed an exercise in prioritization of additional conservation areas needed for their protection. Information related to geographical distribution and evolutionary distinctiveness were considered in setting conservation goals for each species. Thus, we have prioritized the most relictual species, because they are phylogenetically rare, and the species of more restricted distribution, because restricted distribution ranges are associated with higher vulnerability to extinction in cases where habitat destruction pop up simultaneously in several points of the landscape. This study contributes to the proposed priority areas already published for the Cerrado through the inclusion of relevant evolutionary information and the use a more refined and complete database.