Thomas Ledig F.,U.S. Department of Agriculture |
Thomas Ledig F.,University of California |
Rehfeldt G.E.,U.S. Department of Agriculture |
Saenz-Romero C.,Universidad Michoacana de San Nicolas de Hidalgo |
Flores-Lopez C.,Antonio Narro Agrarian Autonomous University
American Journal of Botany | Year: 2010
Premise of the study: Modeling the contemporary and future climate niche for rare plants is a major hurdle in conservation, yet such projections are necessary to prevent extinctions that may result from climate change.Methods: We used recently developed spline climatic models and modifi ed Random Forests statistical procedures to predict suitable habitats of three rare, endangered spruces of Mexico and a spruce of the southwestern USA. We used three general circulation models and two sets of carbon emission scenarios (optimistic and pessimistic) for future climates.Key results: Our procedures predicted present occurrence perfectly. For the decades 2030, 2060, and 2090, the ranges of all taxa progressively decreased, to the point of transient disappearance for one species in the decade 2060 but reappearance in 2090. Contrary to intuition, habitat did not develop to the north for any of the Mexican taxa; rather, climate niches for two taxa re-materialized several hundred kilometers southward in the Trans-Mexican Volcanic Belt. The climate niche for a third Mexican taxon shrank drastically, and its two mitotypes responded differently, one of the first demonstrations of the importance of intraspecifi c genetic variation in climate niches. The climate niche of the U.S. species shrank northward and upward in elevation.Conclusion: The results are important for conservation of these species and are of general signifi cance for conservation by assisted colonization. We conclude that our procedures for producing models and projecting the climate niches of Mexican spruces provide a way for handling other rare plants, which constitute the great bulk of the world' s endangered and most vulnerable flora. © 2010 Botanical Society of America.
Cavazos-Cadena R.,Antonio Narro Agrarian Autonomous University |
Hernandez-Hernandez D.,Research Center en Matematicas
Mathematics of Operations Research | Year: 2016
This work is concerned with finite-state irreducible Markov decision chains satisfying continuity-compactness requirements. It is supposed that the system is driven by a decision maker with utility function U, which, aside mild conditions, is arbitrary, and the performance of a control policy is measured by the long-run average cost criterion induced by U. The main conclusions about this performance index are as follows: (i) the optimal U-average value function coincides with the optimal V -average index for a certain exponential utility V , and (ii) the average criteria associated with U and V have the same class of optimal stationary policies. © 2016 INFORMS.
Martinez O.,National Polytechnic Institute of Mexico |
Reyes-Valdes M.H.,Antonio Narro Agrarian Autonomous University |
Herrera-Estrella L.,National Polytechnic Institute of Mexico
PLoS ONE | Year: 2010
A central goal of cancer biology is to understand how cells from this family of genetic diseases undergo specific morphological and physiological changes and regress to a de-regulated state of the cell cycle. The fact that tumors are unable to perform most of the specific functions of the original tissue led us to hypothesize that the degree of specialization of the transcriptome of cancerous tissues must be less than their normal counterparts. With the aid of information theory tools, we analyzed four datasets derived from transcriptomes of normal and tumor tissues to quantitatively test the hypothesis that cancer reduces transcriptome specialization. Here, we show that the transcriptional specialization of a tumor is significantly less than the corresponding normal tissue and comparable with the specialization of dedifferentiated embryonic stem cells. Furthermore, we demonstrate that the drop in specialization in cancerous tissues is largely due to a decrease in expression of genes that are highly specific to the normal organ. This approach gives us a better understanding of carcinogenesis and offers new tools for the identification of genes that are highly influential in cancer progression. © 2010 Martínez et al.
Sanchez-Pea S.R.,Antonio Narro Agrarian Autonomous University
Florida Entomologist | Year: 2010
The fungus-growing ants (Hymenoptera: Formicidae: Attini) of northeastern Mexico are poorly known. Herein new distributional records in NE Mexico and habitat observations are provided for the fungus-growing ants Apterostigma mexicanum Lattke, Atta texana (Buckley), Cyphomyrmex rimosus (Spinola), Mycocepurus smithii Forel, Mycetosoritis hartmanni Wheeler, Sericomyrmex aztecus Wheeler, Trachymyrmex smithi Buren, and Trachymyrmex turrifex Wheeler.
Reyes-Valdes M.H.,Antonio Narro Agrarian Autonomous University
Methods in Molecular Biology | Year: 2013
Simple sequence repeats (SSR) are extensively used as genetic markers for studies of diversity, genetic mapping, and cultivar discrimination. The informativeness of a given SSR locus or a loci group depends on the number of alleles, their frequency distribution, as well as the kind of application. Here I describe several methods for calculating marker informativeness, all of them suitable for SSR polymorphisms, proposed by several authors and synthesized in an Information Theory framework. Additionally, free access software resources are described as well as their application through worked examples. © Springer Science+Business Media, LLC 2013.