Gustavo F. Aguilar-Martínez

Bio: Gustavo F. Aguilar-Martínez is an academic researcher from Instituto Politécnico Nacional. The author has contributed to research in topics: Genetic divergence & Holocene. The author has an hindex of 2, co-authored 4 publications receiving 23 citations.

Alternative glacial-interglacial refugia demographic hypotheses tested on Cephalocereus columna-trajani (Cactaceae) in the intertropical Mexican drylands.

Abstract: Historic demography changes of plant species adapted to New World arid environments could be consistent with either the Glacial Refugium Hypothesis (GRH), which posits that populations contracted to refuges during the cold-dry glacial and expanded in warm-humid interglacial periods, or with the Interglacial Refugium Hypothesis (IRH), which suggests that populations contracted during interglacials and expanded in glacial times. These contrasting hypotheses are developed in the present study for the giant columnar cactus Cephalocereus columna-trajani in the intertropical Mexican drylands where the effects of Late Quaternary climatic changes on phylogeography of cacti remain largely unknown. In order to determine if the historic demography and phylogeographic structure of the species are consistent with either hypothesis, sequences of the chloroplast regions psbA-trnH and trnT-trnL from 110 individuals from 10 populations comprising the full distribution range of this species were analysed. Standard estimators of genetic diversity and structure were calculated. The historic demography was analysed using a Bayesian approach and the palaeodistribution was derived from ecological niche modelling to determine if, in the arid environments of south-central Mexico, glacial-interglacial cycles drove the genetic divergence and diversification of this species. Results reveal low but statistically significant population differentiation (FST = 0.124, P < 0.001), although very clear geographic clusters are not formed. Genetic diversity, haplotype network and Approximate Bayesian Computation (ABC) demographic analyses suggest a population expansion estimated to have taken place in the Last Interglacial (123.04 kya, 95% CI 115.3-130.03). The species palaeodistribution is consistent with the ABC analyses and indicates that the potential area of palaedistribution and climatic suitability were larger during the Last Interglacial and Holocene than in the Last Glacial Maximum. Overall, these results suggest that C. columna-trajani experienced an expansion following the warm conditions of interglacials, in accordance with the GRH.

Nuevos registros de anfibios y reptiles para Guanajuato, procedentes de la reserva de la biosfera sierra gorda de Guanajuato y zonas adyacentes

Abstract: RESUMEN . La presente contribucion tiene como objetivo dar a conocer seis nuevos registros deanfibios y reptiles y confirmar la presencia de una especie en Guanajuato. Los ejemplares fueroncolectados entre los anos 2003 y 2006 en varias localidades de los municipios de San Luis de la Paz,Victoria y Xichu, que actualmente forman parte de la Reserva de la Biosfera “Sierra Gorda deGuanajuato” y se depositaron en la coleccion Herpetologica de la Escuela Nacional de CienciasBiologicas, del I.P.N. Los nuevos registros de anfibios son: Chaunus marinus y Ollotis nebulifer, los dereptiles son: Sceloporus variabilis, Plestiodon tetragrammus, Boa constrictor y Masticophis flagellum. El registro de Lithobates berlandieri confirma la presencia de esta especie en Guanajuato. Palabras clave: anfibios, reptiles, Guanajuato, nuevos registros. Campos-Rodriguez, J. I., C. Elizalde-Arellano, J. C. Lopez-Vidal, G. F. Aguilar-Martinez, S. N.Ramos-Reyes & R. Hernandez-Arciga. 2009. Noteworthy records of amphibians and reptiles ofGuanajuato, collected at the Biosphere Reserve of “Sierra Gorda of Guanajuato” and adjacentzones.

Reporte del tamaño de una camada de Barisia imbricata (Wiegmann, 1828) (Reptilia: Anguidae)

Abstract: The genus Barisia is endemic to Mexico occurring in temperate regions, at elevations between 2200-3800 m above sea level. Few records of clutch size of the species of Barisia are available, in particular for B. imbricata. The first report of a large clutch size (15 neonates alive) is given for this species.

Phylogenetic Relationships and Evolutionary Trends in the Cactus Family.

Abstract: Members of the cactus family are keystone species of arid and semiarid biomes in the Americas, as they provide shelter and resources to support other members of ecosystems. Extraordinary examples are the several species of flies of the genus Drosophila that lay eggs and feed in their rotting stems, which provide a model system for studying evolutionary processes. Although there is significant progress in understanding the evolution of Drosophila species, there are gaps in our knowledge about the cactus lineages hosting them. Here, we review the current knowledge about the evolution of Cactaceae, focusing on phylogenetic relationships and trends revealed by the study of DNA sequence data. During the last several decades, the availability of molecular phylogenies has considerably increased our understanding of the relationships, biogeography, and evolution of traits in the family. Remarkably, although succulent cacti have very low growth rates and long generation times, they underwent some of the fastest diversifications observed in the plant kingdom, possibly fostered by strong ecological interactions. We have a better understanding of the reproductive biology, population structure and speciation mechanisms in different clades. The recent publication of complete genomes for some species has revealed the importance of phenomena such as incomplete lineage sorting. Hybridization and polyploidization are common in the family, and have been studied using a variety of phylogenetic methods. We discuss potential future avenues for research in Cactaceae, emphasizing the need of a concerted effort among scientists in the Americas, together with the analyses of data from novel sequencing techniques.

The role of seed dispersers in the population dynamics of the columnar cactus neobuxbaumia tetetzo

Abstract: We examined the effect of frugivorous bats and birds on the population dynamics of the giant columnar cactus Neobuxbaumia tetetzo in the Tehuacán Valley, Mexico. Because successful seedling establishment occurs only beneath the canopies of shrubs and trees, we hypothesized that seed dispersal is a key process in the maintenance of its populations. We determined the dispersal effectiveness of different frugivores, conside¡:ing the quantity and quality components of seed dispersa!. We algo evaluated the potential effects of each frugivore species on the finite cate of increase of N. tetetzo populations by modifying the fecundity values of a Lefkovitch matrix mode!. The bat Leptonycteris curasoae had the highest effectiveness whereas the bird Carpodacus mexicanus had the lowest. The estimated finite cates of increase calculated to evaluate the effects of frugivores on the population dynamics of the cactus differ marginally from unity, except ",h..n th.. ..l'f t "f th.. hgt T N.~no~~n nmo gng!"7..A (" ~ ...onl+o rn~~"r' 'kg' .k.. kg' .. u_u >u_u_n --_o -. -_o n -_U_'J --_o ~-' ._~_.>~ ~-óó-~> >u_> >uu_> Leptonycteris curasoae could be considered the legitimate dispersal agent of N. tetetzo, dispersing seeds directly to gafe sites, and thus representing a key species in the ecology ~" ,"':~ _~1 ---,..-. --'-"'U_' ~.

Pleistocene refugia in the Chihuahuan Desert: the phylogeographic and demographic history of the gymnosperm Ephedra compacta

Abstract: Aim We investigate the influence of late Neogene orogenic activity and Pleistocene glacial-interglacial cycles on intraspecific divergence and demographic history in the gymnosperm shrub Ephedra compacta. We test refugia hypotheses to explain geographical patterns of genetic diversity and phylogeographic structure in a warm North American desert that reaches inter-tropical latitudes. Location Chihuahuan Desert, Mexican Plateau, Sierra Madre Oriental, Tehuacan Valley. Methods Geographical patterns of genetic diversity were estimated using chloroplast DNA sequences of 191 individuals from 24 populations. AMOVA and SAMOVA analyses were used to assess population and phylogeographic structure, respectively. Approximate Bayesian computation (ABC) was implemented to test phylogeograhic scenarios of population divergence and demographic expansion. Ecological niche modelling (ENM) was performed to predict the potential distribution of E. compacta during the late Pleistocene and to estimate historical habitat stability. Refugia hypotheses were tested by estimating the linear associations between habitat stability, latitude and parameters of genetic diversity. Results High levels of population and phylogeographic structure were observed with six geographical groups explaining most of the variation. The best-supported phylogeographic scenario assumed population divergence and demographic expansion during the Pleistocene. ENM predictions showed historical changes in the potential distribution of E. compacta, with a broader geographical extent in the present. Habitat stability was positively associated with population genetic diversity. Main conclusions The intraspecific population divergence and demographic expansion in E. compacta is probably associated with the glacial-interglacial cycles of the Pleistocene. Our ENM predictions also support a scenario of habitat contraction and expansion during this time period. The phylogeographic history of E. compacta is predicted by climate refugia dynamics in which specific areas, primarily in the Mexican Plateau harbour the highest levels of habitat stability and genetic diversity.

Historic range dynamics in Kaiser's mountain newt (Neurergus kaiseri): Insights from phylogeographic analyses and species distribution modeling.

Abstract: Vulnerable Kaiser's mountain newt, Neurergus kaiseri, is endemic to highland streams, springs, and pools of the southwestern Zagros mountain, Iran. The present study aimed to use an integration of phylogeographical and species distribution modeling (SDM) approaches to provide new insights into the evolutionary history of the species throughout Quaternary climate oscillations. The phylogeographical analysis was followed by analyzing two mitochondrial DNA (mt-DNA) markers including 127 control region (D-loop) and 72 NADH dehydrogenase 2 (ND2) sequences from 15 populations in the entire species range that were obtained from GenBank. Potential recent and past distribution (the Last Glacial Maximum, LGM, 21 Kya and the Mid-Holocene, 6 Kya) reconstructed by ensemble SDM using nine algorithms with CCSM4, MIROC-ESM, and MPI-ESM-P models. N. kaiseri displayed two distinct lineages in the northern and southern regions that diverged in the Early-Pleistocene. The demographics analysis showed signs of a slight increase in effective population size for both northern and southern populations in the Mid-Pleistocene. Biogeography analysis showed that both vicariance and dispersal events played an important role in the formation of recent species distribution of N. kaiseri. Based on SDM projection onto paleoclimatic data, N. kaiseri displayed a scenario of past range expansion that followed by postglacial contraction. The models showed that the distribution range of the species may have shifted to a lower altitude during LGM while with amelioration of climatic during Mid-Holocene to recent conditions caused the species to shift to the higher altitude. The findings of the current study support the hypothesis that the Zagros mountains​ may be acting as climatic refugia and play an important role in the protection of isolated populations during climate oscillations.

Pleistocene diversification in an ancient lineage: a role for glacial cycles in the evolutionary history of Dioon Lindl. (Zamiaceae).

Abstract: PREMISE OF THE STUDY Recent estimates of crown ages for cycad genera (Late Miocene) challenge us to consider what processes have produced the extant diversity of this ancient group in such relatively little time Pleistocene climate change has driven major shifts in species distributions in Mexico and may have led to speciation in the genus Dioon by forcing populations to migrate up in elevation, thereby becoming separated by topography METHODS We inferred orthologs from transcriptomes of five species and sequenced these in 42 individuals representing all Dioon species From these data and published plastid sequences, we inferred dated species trees and lineage-specific diversification rates KEY RESULTS Analyses of 84 newly sequenced nuclear orthologs and published plastid data confirm four major clades within Dioon, all of Pleistocene age Gene tree analysis, divergence dates, and an increase in diversification rate support very recent and rapid divergence of extant taxa CONCLUSIONS This study confirms the Pleistocene age of Dioon species and implicates Pleistocene climate change and established topography in lineage spitting These results add to our understanding of the cycads as evolutionarily dynamic lineages, not relicts or evolutionary dead ends We also find that well-supported secondary calibration points can be reliable in the absence of fossils Our hypothesis of lineage splitting mediated by habitat shifts may be applicable to other taxa that are restricted to elevation specific ecotones