A delimitação geográfica de um bioma engloba questões que envolvem fatores ambientais, como clima e características da vegetação, além de aspectos políticos. Consequentemente, variações na delimitação de um bioma são recorrentes. A Mata Atlântica é um dos mais importantes hotspots de biodiversidade do mundo e historicamente diversas delimitações territoriais foram propostas para esse bioma. Aqui tivemos como objetivo 1) discutir as quatro principais delimitações e 2) com base nos limites existentes, discutir sua união (Limite Integrativo) e intersecção (Limite Consensual). Os principais limites apresentam áreas consensuais e integrativas de 1,01 e 1,62 milhão km 2 , respectivamente. Cinco regiões de divergência devem ser cuidadosamente avaliadas. Finalmente, sugerimos um debate sobre o uso de limites em estudos ecológicos e sua aplicação em estudos sobre conservação da biodiversidade. Palavras-chave: biogeografia histórica; bioma; distribuição geográfica; floresta tropical; hotspot de biodiversidade. A NOTE ON THE TERRITORIAL LIMITS OF THE ATLANTIC FOREST. The geographic delimitation of a biome encompasses questions that involve environmental factors such as climate and vegetation characteristics as well as political aspects. Consequently, variation on biome delimitation is recurrent. The Atlantic Forest is one of the most important biodiversity hotspots in the world, and historically several territorial delimitations have been proposed for this biome. Here we aim to 1) discuss the four main delimitations and 2) based on the existing limits, discuss their union (Integrative limit) and intersection (Consensual limit). The main limits present consensual and integrative areas of 1.01 and 1.62 million km 2 , respectively. Five regions of divergence must be carefully evaluated. Finally, we suggest a debate about the use of limits in ecological studies and their application in biodiversity conservation studies.
Sample size sufficiency is a critical consideration for conducting Resource-Selection Analyses (RSAs) from GPS-based animal telemetry. Cited thresholds for sufficiency include a number of captured animals M ≥ 30 and as many relocations per animal N as possible. These thresholds render many RSA-based studies misleading if large sample sizes were truly insufficient, or unpublishable if small sample sizes were sufficient but failed to meet reviewer expectations. We provide the first comprehensive solution for RSA sample size by deriving closed-form mathematical expressions for the number of animals M and the number of relocations per animal N required for model outputs to a given degree of precision. The sample sizes needed depend on just 2 biologically meaningful quantities: habitat selection strength and a novel measure of landscape complexity, which we define rigorously. The mathematical expressions are calculable for any environmental dataset at any spatial scale and are applicable to any study involving resource selection (including sessile organisms). We validate our analytical solutions using globally relevant empirical data including 5,678,623 GPS locations from 511 animals from 10 species (omnivores, carnivores, and herbivores living in boreal, temperate, and tropical forests, montane woodlands, swamps, and arctic tundra). Our analytic expressions show that the required M and N must decline with increasing selection strength and increasing landscape complexity, and this decline is insensitive to the definition of availability used in the analysis. Our results contradict conventional wisdom by demonstrating that the most biologically relevant effects on the utilization distribution (i.e. those landscape conditions with the greatest absolute magnitude of resource selection) can often be estimated with far fewer data than is commonly assumed. We identify several critical steps in implementing these equations, including (i) a priori selection of expected model coefficients, and (ii) sampling intensity for background (absence/pseudo-absence) data within a given definition of availability. We show that random sampling of background data violates the underlying mathematics of RSA, leading to incorrect values for necessary M and N and potentially incorrect RSA model outputs. We argue that these equations should be a mandatory component for all future RSA studies.
The range-wide management of the jaguar (Panthera onca) depends upon maintaining core populations connected through multi-national, transboundary cooperation, which is dependent upon understanding the movement ecology and space use of jaguars throughout their range. Using 117 telemetry trajectories from 12 ecoregions, we examined the landscape-level environmental and anthropogenic factors related to jaguar home range size and movement parameters. Range-wide and at the ecoregional scale home range size decreased with increasing net productivity and increased with increasing road density. Also, range-wide, home range size decreased with increasing forest cover and decreasing human population density. Movement within home ranges was best explained by a different set of environmental covariates. Range-wide predictions of home range size were consistent with expectations based upon density estimates. Our findings provide a mechanism to evaluate range-wide habitat quality for jaguars and an inferential modeling framework that can be adapted to the conservation of other large terrestrial carnivores.
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