Evaluation of different aspects of maximum entropy for niche-based modeling

AbstractBiodiversity conservation is a world challenge that needs attention and efficient strategies for its success. Modeling of geographic distributions of species is used in assorted applications related to biodiversity conservation. Maximum entropy (maxent) is a technique recently applied to modeling of geographic distributions of species and is being largely used by biologists. The aim is to evaluate different viewpoints of this technique. The first evaluation is concerned with the performance of the algorithm. A parallel version of the maxent-based algorithm available in openModeller is presented. openModeller is a set of tools provided for researchers interested in modeling of geographic distributions of species. The second evaluation is focused on tuning the regularization parameter, since it can severely affect the performance of the algorithm and can take a long time to be adjusted. In addition, the algorithm was evaluated without the use of a regularization parameter and with an adaptive maximum entropy approach. This approach was evaluated as a replacement of the regularization parameter. The validation of the assessments was based on a dataset with 20 species. The results show: an improvement in the algorithm performance using parallelism, considering only the running time; the regularization parameter does not depend on the number of samples, or on the number of iterations in training; species with the same number of samples fit better with different values of the regularization parameter (different magnitude order); the adaptive approach cannot replace the regularization parameter

A new species of tapir from the Amazon

All known species of extant tapirs are allopatric: 1 in southeastern Asia and 3 in Central and South America. The fossil record for tapirs, however, is much wider in geographical range, including Europe, Asia, and North and South America, going back to the late Oligocene, making the present distribution a relict of the original one. We here describe a new species of living Tapirus from the Amazon rain forest, the 1st since T. bairdii Gill, 1865, and the 1st new Perissodactyla in more than 100 years, from both morphological and molecular characters. It is shorter in stature than T. terrestris (Linnaeus, 1758) and has distinctive skull morphology, and it is basal to the clade formed by T. terrestris and T. pinchaque (Roulin, 1829). This highlights the unrecognized biodiversity in western Amazonia, where the biota faces increasing threats. Local peoples have long recognized our new species, suggesting a key role for traditional knowledge in understanding the biodiversity of the region

Prolonged caffeine intake decreases alveolar bone damage induced by bingelike ethanol consumption in adolescent female rats

Ethanol consumption has been reported to negatively impact on periodontal disease. In particular, oral cavity disorders occur upon ethanol exposure during adolescence, a life period associated with particular patterns of short and intense (‘binge-like’) ethanol consumption that is most deleterious to oral health. The hazardous central effects of ethanol have been linked to the overfunction of adenosine receptors, which are antagonized by caffeine, a bioactive substance present in numerous natural nutrients, which can also modify bone metabolism. The aim of this study was to investigate the effects of caffeine on alveolar bone damage induced by an ethanol binge drinking paradigm during adolescence. Female Wistar rats (35 days old; n = 30) were allocated to six groups: control (vehicle), ethanol (3 g/kg/day; 3 days On-4 days Off challenge), caffeine (10 mg/kg/day), caffeine plus ethanol, SCH58261 (0.1 mg/kg/day, an antagonist of A2A receptors), and SCH58261 plus ethanol. Bone micromorphology and vertical bone loss were analyzed by computed microtomography. Our data showed that ethanol binge drinking reduced alveolar bone quality, with repercussion on alveolar bone size. This ethanolinduced alveolar bone deterioration was abrogated upon treatment with caffeine, but not with SCH58261. This shows that caffeine prevented the periodontal disorder caused by ethanol binge drinking during adolescence, an effect that was not mediated by adenosine A2A receptor blockad