| 1 | Anatomical variation of five plant species along an elevation gradient in Mexico City basin within the Trans-Mexican Volcanic Belt, Mexico显示文摘Change in environmental conditions with altitudinal gradients induces morpho-anatomical variations in plants that have been poorly documented in intertropical regions. Five species with three life forms, cryptophyte(Alchemilla procumbens, Geranium seemannii), hemicryptophyte(Acaena elongata, Lupinus montanus), and phanerophyte(Symphoricarpos microphyllus), distributed along an altitudinal gradient in the Sierra Nevada of central Mexico, were studied. The aims were to identify and evaluate their morpho-anatomical modifications under the hypothesis that the sizes of individuals and of their wood and leaf cell types decrease as elevation increases. Three individuals per species per site were collected at seven locations along the altitudinal gradient(2949-3952 m). Their morpho-anatomical characters were analyzed through multiple regression analyses. Elevation was the variable that best explained anatomical changes in the leaf and wood ofthe five species. Canopy density and potassium content in the soil also contributed to explain the variation in anatomical variables along the gradient. As elevation increased a bimodal pattern was observed in various anatomical characters as in the leaf width of A. elongata, A. procumbens and G. seemannii and in the vessel diameter of A. procumbens, G. seemannii, and L. montanus. Other features as the vessel diameter of A. elongata, the fiber length of S. microphyllus, and the ray width of A. elongata increased as the elevation increased. Anatomical traits have a tendency to decrease in size but just toward the end of the gradient, which is probably related to changes in canopy density. The plant response to the altitudinal gradient is more focused on anatomical adaptations than morphological variation; it is also species dependent. | P Mayte S.JIMéNEZ-NORIEGA Teresa TERRAZAS Lauro LóPEZ-MATA Arturo SáNCHEZ-GONZáLEZ Heike VIBRANS | 2017 | Journal of Mountain Science2017，14，11： | 1 |
| 3 | The importance of the Mexican taxa of Asteraceae in the family phylogeny显示文摘Asteraceae is the largest plant family in México with about 417 genera and 3113 species,and with more than 60%of them being endemic.Phylogenetic relationships at subfamily and tribal levels have been previously resolved employing both nuclear and plastid molecular markers.However,Asteraceae species native to Mexico have been underrepresented in such phylogenies.To tackle this issue,the taxon sampling of this study included 90 Asteraceae species native to México,four species from the Caribbean,119 previously sequenced species,and six outgroups.With this sampling,all the Asteraceae subfamilies and all of the tribes recognized to date are represented.The analyzed dataset consisted of eleven chloroplast markers(atpB,matK,ndhC,ndhD,ndhF,ndhI,ndhJ,ndhK,rbcL,trnL-trnF,and 23S-trnA).We present two phylogenetic reconstructions obtained by maximum likelihood and pseudocoalescent methods.Besides,we present a time-calibrated phylogeny,which is used to infer the best configuration of diversification rate shifts.Our results show that Mexican species are distributed mainly in the subfamily Asteroideae(80 species),followed by Cichorioideae(6 species),Carduoideae(2 species),and Mutisioideae(2 species).Four net diversification rate shifts were found:One near the base of the tree and four within Asteroideae subfamily.Our extended sampling of the family with the representation of native species to Mexico allowed us to identify important events in the evolutionary history of the family. | Patricia Rivera Jose Luis Villasenor Teresa Terrazas Jose L.Panero | 2021 | Journal of Systematics and Evolution2021，59，5： | 0 |
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