TÔ rres and R o g É r i o P e r e i r a B a s t o s Abstract Increasing rates of habitat loss and human occupation are creating demands for optimum strategies that maximize conservation efforts, despite the lack of detailed data required for implementation. Broad scale biogeographical data may furnish initial guidelines for conservation planning in a hierarchical framework for establishing conservation priorities and helping guide future research programmes. This approach may be critical in regions for which few detailed data on diversity, abundance and distribution are available, such as in the Cerrado biome of central Brazil. We used a macroecological approach, based on the extent of occurrence of 127 species of terrestrial vertebrates endemic to the Cerrado, to design a regional network of potential areas that represent all species at least once. The final network has a total of 24 regions widely distributed throughout the biome. We also evaluated these regions in terms of their human occupation by adding a cost for each cell based on 23 variables expressing variation in agricultural, demographic and cattle-ranching patterns on the Cerrado. Our analyses showed that conservation efforts should be concentrated in the south and south-east of the biome. This macroecological approach can provide broad guidelines for conservation and define the focus for more local and realistic conservation efforts.
Spatial autocorrelation is the lack of independence between pairs of observations at given distances within a geographical space, a phenomenon commonly found in ecological data. Taking into account spatial autocorrelation when evaluating problems in geographical ecology, including gradients in species richness, is important to describe both the spatial structure in data and to correct the bias in Type I errors of standard statistical analyses. However, to effectively solve these problems it is necessary to establish the best way to incorporate the spatial structure to be used in the models. In this paper, we applied autoregressive models based on different types of connections and distances between 181 cells covering the Cerrado region of Central Brazil to study the spatial variation in mammal and bird species richness across the biome. Spatial structure was stronger for birds than for mammals, with R(2) values ranging from 0.77 to 0.94 for mammals and from 0.77 to 0.97 for birds, for models based on different definitions of spatial structures. According to the Akaike Information Criterion (AIC), the best autoregressive model was obtained by using the rook connection. In general, these results furnish guidelines for future modelling of species richness patterns in relation to environmental predictors and other variables expressing human occupation in the biome.
Declines in anuran populations worldwide are increasingly creating demands for quick and urgent strategies to maximize efforts to conserve amphibian populations, especially in areas in which few detailed data on diversity, abundance and distribution are available, such as the Cerrado of Central Brazil. We used extent of occurrence of 105 species of Anura (Amphibia) in the Cerrado region to establish a regional system of potential areas that preserves all anuran species in the region, at a macroecological scale. The nal network, obtained using a simple "greedy" algorithm based on complementarity, has a total of 10 regions, widely distributed in the biome. These areas were also evaluated in terms of their human demographic parameters (human population size and growth rate). Strong spatial autocorrelation in species richness indicates that alternative systems based on pre-existing conservation units will also be ef cient in terms of biodiversity conservation. Although macro-scale approaches are usually coarse, they can provide overall guidelines for conservation and de ne the focus for more local and effective conservation efforts, which is particularly important when dealing with a taxonomic group such as anurans for which quick and drastic population declines have been reported in many regions of the world.
grupos indicadores pode ser importante para minimizar problemas gerados pela falta de conhecimento. Assim, essa abordagem é interessante em um cenário de grandes incertezas (ausência de dados detalhados) e de rápida transformação da paisagem, possibilitando a otimização de estudos em grandes escalas e depois transferir os resultados para escalas espaciais mais locais e realmente relevantes para a conservação. nessas regiões, podem ser realizados, em um segundo momento, estudos mais detalhados a fim de avaliar padrões de viabilidade populacional, fragmentação de habitat e regiões potenciais de manutenção da diversidade genética.
Macroecological variables of Anuran species found in a local assemblage from Central Brazil (Silvânia, Goiás State) were linked to population dyamics statistics of these species. Geographical range size (GRS), body size, and species' midpoints were the macroecological variables investigated for those species found in the local assemblage and for all other species (105 in the total) found in the Cerrado biome. For each species found in the local assemblage, data on abundance was obtained. Using this data, local population variability as expressed by the coefficient of variation was estimated. Distribution of means, medians, maximum, variances, and skewness (g1), for both GRS and body size, estimated in the local assemblage were compared, using null models, with the data extracted from the overall Cerrado species pool. The results indicated a clear macroecological relationship between GRS and body size and a decrease in local abundance when distance between the locality analyzed and species midpoint increased. According to null models, both body size and GRS values measured in the local assemblage can be considered a random sample from the regional species pool (Cerrado region). Finally, a three-dimensional analysis using body size, GRS, and local population estimates (abundance and variability), indicated that less abundant and more fluctuating species fell near the lower boundary of the polygonal relationship between GRS and body size. Thus, macroecological results linked with local data on population dynamics supported the minimum viable population model.
Spatial patterns in biodiversity variation at a regional scale are rarely taken into account when a natural reserve is to be established, despite many available methods for determining them. In this paper, we used dimensions of occurrence of 105 species of Anura (Amphibia) in the cerrado region of central Brazil to create a regional system of potential areas that preserves all regional diversity, using three different algorithms to establish reserve networks: "greedy", rarity, and simulated annealing algorithms. These generated networks based on complementarity with 10, 12, and 8 regions, respectively, widely distributed in the biome, and encompassing various Brazilian states. Although the purpose of these algorithms is to find a small number of regions for which all species are represented at least once, the results showed that 67.6%, 76.2%, and 69.5% of the species were represented in two or more regions in the three networks. Simulated annealing produced the smallest network, but it left out three species (one endemic). On the other hand, while the greedy algorithm produce a smaller solution, the rarity-based algorithm ensured that more species were represented more than once, which can be advantageous because it takes into consideration the high levels of habitat loss in the cerrado. Although usually coarse, these macro-scale approaches can provide overall guidelines for conservation and are useful in determining the focus for more local and effective conservation efforts, which is especially important when dealing with a taxonomic group such as anurans, for which quick and drastic population declines have been reported throughout the world.
ABSTRACT. Macroecology of neotropical mammals with occurrence in the brazilian "Cerrado". The macroecological approach has been used recently to analyze corre lations between ecological variables in large taxonomic groups, at continental scales. A positive relationship between body weight and geographi c range size has been described as a poligonal space envelope form, that can be explained by ecological and evolutionaty constraints. However, these variables can be disturbed by spatial and phylogenetic autocorrelation effects. In this work, the relationship between body weight and geographic range size was analyzed for 80 species of Neotropical mammals present in lhe Brazilian "cerrado". Spatial and taxonomic effects were tested using a linear trend surface analysis and an ANOVA (at leveI of order), combined in a generalized model. Around 61 % of variation in geographic range size and 69% of variation in body weight in mammals ofthe "cerrado" can be explained simultaneously by spatial and taxonomic effects. The analysis 01' residuaIs of the generalized model showed that positive correlation between variables persist even atier removing these effects. Thus, variation and covariati on or traits in the maml11als or the brazilian "cerrado" agree with the general macroecological pattem proposed for another laxonomic groups such as l11aml11als, birds and snakes worldwilde. KEY WORDS . Macroecology, "Cell'ado" mammals, geographic range size, ecological and evolutionaty constraints, spatia l and phylogenetic autocorrelation A macroecologia analisa as relações entre variáveis ecológicas mensuradas em escalas grandes de tempo e espaço (BROWN & MAURER 1987 LEVrN 1992;BROWN 1995). A análise de variáveis macroecológicas, tais como o tamanho do corpo, área de distribuição e densidade populacional local das espécies, mensuradas em grandes grupos taxonômicos em escalas continentais, pode revelar processos ecológicos e evolutivos que participam na estruturação das comunidades (LABARBERA 1989;PETERS 1993; RlCKLEFS & SCHLUTER 1993;BROWN 1995).Dentre as principais relações macroecológicas, a obtida entre o tamanho do corpo (definida pela massa corpórea) e a área de distribuição das espécies tem sido descrita para diversos grupos taxonômicos, tais como insetos, peixes, aves e mamíferos, principalmente da América do Norte
Patterns and processes in body size evolution of south american carnivoresIn the last few years, many models have been proposed to link microevolutionary processes to macroevolutionary patterns, defined by comparative data analysis. Among these, Brownian motion and Ornstein-Uhlenbeck (O-U) processes have been used to model, respectively, genetic drift and stabilizing selection.Since these models produce different curves of pairwise variance between species against time since divergence, different profiles in phylogenetic correlograms must appear. In this paper, we analyzed variation in body weight among 17 species of South American carnivores by means of phylogenetic correlograms, constructed using Moran's I coefficients in four distance classes. Phylogeny among species was based on molecular data.The observed correlogram was then compared with 400 simulated correlograms of Brownian motion and O-U over the same phylogeny. The observed correlogram indicates a phylogenetic gradient up to 8 mya, when coefficients tend to stabilize, and autoregressive model indicates that around 74% of the interspecific variance in body size can be explained by phylogenetic inertia. This is expected by considering that body size is usually correlated with many ecological and lifehistory traits, being subjected to many constraints that can be modeled by O-U process expressing stabilizing selection.Key words: carnivores, body size, phylogeny, autocorrelation, correlograms, stabilizing selection. RESUMONos últimos anos, muitos modelos têm sido propostos a fim de ligar os processos microevolutivos aos padrões macroevolutivos. Dentre estes, o movimento Browniano e o processo Ornstein-Uhlenbeck (O-U) têm sido utilizados, respectivamente, para modelar a evolução de um caráter quantitativo sob efeito de deriva genética e seleção estabilizadora.Uma vez que esses processos produzem curvas diferentes de relação entre variância interespecífica e tempo de divergência, eles podem ser distinguidos através de correlogramas filogenéticos. Neste trabalho, padrões no tamanho do corpo de 17 espécies de Carnívora sul-americanos foram analisados através de correlogramas filogenéticos, construídos com índices I de Moran em quatro classes de distância no tempo.O correlograma observado foi comparado a 400 correlogramas obtidos através de simulações dos dois processos (movimento Browniano e O-U) sobre a filogenia das espécies analisadas (obtida
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