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Understanding the mechanisms that drive the assembly of communities is a central goal in ecology, and phylogenetic approaches allows for the testing of hypotheses related to such mechanisms. We analyzed assembly mechanisms of cricetid rodents in an environmentally heterogeneous region of southern Mexico by assessing their phylogenetic diversity and testing environmental predictors of the phylogenetic structure of local communities. We expected different assembly mechanisms among subprovinces according to their environmental heterogeneity. To test this, we obtained potential communities in cells of 100 km2 by overlapping potential distribution models of 49 species of cricetids. We also estimated a phylogenetic tree using sequences of Cytb obtained from GenBank and used null models to estimate the phylogenetic diversity of communities. We found two phylogenetic diversity patterns: overdispersion in lowlands and clustering in mountains. However, for the majority of the cells, the observed phylogenetic diversity does not differ from that of null models, suggesting that stochastic processes are the main drivers of the Cricetid communities. Only 25% of the communities located in the Sierra Madre de Oaxaca exhibited significant phylogenetic clustering, indicating that habitat filtering structures their composition. According to Generalized Additive Models, all environmental variables (elevation, temperature, precipitation, net primary productivity, and potential evapotranspiration) were highly significant predictors of phylogenetic diversity. Communities at lowest elevations and warmest temperatures showed the highest phylogenetic diversity values. Despite the role of environmental factors and low vagility of cricetids, our results showed that stochastic processes explained the assembly of communities more than deterministic ones, although in mountainous areas habitat filtering was also an outstanding mechanism. This study highlights the importance of including phylogenetic information to understand the mechanisms by which communities of small mammals are assembled. [ABSTRACT FROM AUTHOR]

Photosynthetic productivity is a key determinant of the abundance and distribution of biodiversity around the world. The effect of this productivity on the distribution patterns of mammals is frequently invoked; however, it is seldom measured directly. In this study, we used Sherman live traps set in dry and rainy seasons across a 2300-m elevation gradient in southwestern Mexico to assess small rodent species distributions, and to relate these patterns to habitat structure, climate, and a well-accepted measure of photosynthetic productivity: the normalized difference vegetation index (NDVI). While habitat structure and climate helped explain some of the patterns observed, NDVI proved to be the most important contributing variable for most of the distribution models. We also found that partitioning the gradient-distribution model by trapping season revealed strong differences in terms of the effect of NDVI and the other explanatory variables. For example, lower elevations were associated with seasonal and year-round reductions in rodent diversity and were composed almost exclusively of granivore-based species assemblages. By contrast, the middle and upper elevations were more species rich, less affected by seasonality, and characterized by omnivorous species. Our results suggest that the positive productivity–diversity relationship found may be due, at least in part, to increased food resources and niche opportunities at more productive elevations. Increased diversity at the higher elevations may also be partially due to reductions in competition that result from productivity increases, as well as from the broader spectrum of feeding guild representation that it and the lack of seasonality allow. [ABSTRACT FROM AUTHOR]

Understanding the spatiotemporal links between drought and forest fire occurrence is crucial for improving decision-making in fire management under current and future climatic conditions. We quantified forest fire activity in Mexico using georeferenced fire records for the period of 2005-2015 and examined its spatial and temporal relationships with a multiscalar drought index, the Standardized Precipitation-Evapotranspiration Index (SPEI). A total of 47 975 fire counts were recorded in the 11-year long study period, with the peak in fire frequency occurring in 2011. We identified four fire clusters, i.e., regions where there is a high density of fire records in Mexico using the Getis-Ord G spatial statistic. Then, we examined fire frequency data in the clustered regions and assessed how fire activity related to the SPEI for the entire study period and also for the year 2011. Associations between the SPEI and fire frequency varied across Mexico and fire-SPEI relationships also varied across the months of major fire occurrence and related SPEI temporal scales. In particular, in the two fire clusters located in northern Mexico (Chihuahua, northern Baja California), drier conditions over the previous 5 months triggered fire occurrence. In contrast, we did not observe a significant relationship between drought severity and fire frequency in the central Mexico cluster, which exhibited the highest fire frequency. We also found moderate fire-drought associations in the cluster situated in the tropical southern Chiapas where agriculture activities are the main causes of forest fire occurrence. These results are useful for improving our understanding of the spatiotemporal patterns of fire occurrence as related to drought severity in megadiverse countries hosting many forest types as Mexico. [ABSTRACT FROM AUTHOR]

Background: With only a third of Latinos achieving sustained virologic response (SVR), there is a need for enhanced HCV treatment. Amantadine has been proposed to improve response rates in addition to standard therapy with peginterferon alpha and ribavirin. Our objective is to evaluate whether triple therapy with amantadine improves SVR rates in this special population.Method: Treatment-naïve Latino subjects with HCV genotype 1 infection were randomized to receive peginterferon alpha-2a plus weight-based ribavirin for 48 weeks (double therapy) or the same regimen plus amantadine 200 mg daily (triple therapy). The primary endpoint was SVR. Predictors of liver fibrosis using APRI and Forns indices were also evaluated.Results: We enrolled 124 patients with chronic hepatitis C genotype 1. Sixty-three received conventional therapy and 61 patients had triple therapy with amantadine. SVR at week 72 was achieved in 25 patients (39.7%) vs. 26 patients (42.6%) in the double and triple regimen, respectively (p=0.561). After multivariate analysis, advanced fibrosis, obesity, and low pretreatment ALT levels were associated with non-response in both groups (p=0.0234, p=0.0012, p=0.0249, respectively). APRI values delimited an area under the ROC curve (AUROC) of 0.724 and Forns index with AUROC of 0.733. There was no difference between both indices in predicting significant fibrosis (Knodell index: F3-F4).Conclusion: Our study demonstrates that the addition of amantadine to standard treatment of chronic HCV does not improve SVR rates in Latino patients with genotype 1. Further research to improve response rates in this special population is needed. [ABSTRACT FROM AUTHOR]

The depressive symptoms are associated with chronic pain in this study. A cross-sectional study was performed. A visual analog scale was used to register pain intensity. Depressive symptoms were measured using the Center of Epidemiological Studies (CES-Dr) scale as modified by Eaton and reviewed for use in the Mexican population. The study included 245 patients, with a mean age of 46 years, 86.1% of whom were female. The prevalence of some degree of depression was 55.1%. Patients with fibromyalgia had the highest prevalence of symptoms of depression (78.38%) and major depression (29.73%). Stepwise multiple regressions indicated that the best model ( r2 = 0.26) to predict the CES-Dr score included the global pain score ( P < 0.0001) and education level ( P < 0.004). The Cronbach’s alpha of the CES-Dr was high (α = 0.888). There was moderate correlation ( r = 0.442), P < 0.0001 of the CES-Dr numeric score with the intensity of global pain. [ABSTRACT FROM AUTHOR]

Examines the criteria used by the Yucatec Mayan communities of Mexico in selecting medicinal plants. Emphasis placed on flavor and aroma; Indication of a plant's medicinal value; Medicinal plants considered to be sweet or aromatic.