María Elena Siqueiros-Delgado

Bio: María Elena Siqueiros-Delgado is an academic researcher from Autonomous University of Aguascalientes. The author has contributed to research in topics: Chloridoideae & Bouteloua. The author has an hindex of 6, co-authored 32 publications receiving 156 citations.

Phylogenetics of Chloridoideae (Gramineae): a Preliminary Study Based on Nuclear Ribosomal Internal Transcribed Spacer and Chloroplast trnL–F Sequences

Abstract: The phylogeny of Chloridoideae (Gramineae) was inferred from parsimony analyses of DNA sequences from two genomes-the chloroplast tmL intron, trnL 3' exon, and trnL-F intergenic spacer, and the nuclear ribosomal internal transcribed spacer region (ITS 1 + 5.8S + ITS2). Eighty species representing 66 chloridoid genera were sampled, including all but four of the native New World genera. Analyses of the individual and combined data sets were performed. The phylogenies were found to be highly congruent. Of the four tribes and seven subtribes of Chloridoideae sensu Clayton and Renvoize (1986) whose phylogenetic status could be tested with our taxon sample, only Orcuttieae and Uniolinae were monophyletic. The phylogenies suggested significant homoplasy in morphological traits, including inflorescence type, number of florets per spikelet, and number of lemma nerves. We propose a new classification based on the three main clades in the phylogenies¯tribes Cynodonteae, Eragrostideae, and Zoysieae. The Eragrostideae clade is well resolved and supported and is further divided into three subtribes, Cotteinae. Eragrostidinae, and Uniolinae. Cynodonteae include most of the genera in our study, but the clade is poorly resolved. However, a clade formed of Muhlenbergia and nine other genera is present in both phylogenies and is well resolved and supported. A number of interesting, well-supported relationships are evident in the phylogenies, including Pappophorum-Tridens flavus, Tragus-Willkommia, and Gouinia-Tridens muticus-Triplasis-Vaseyochloa Except for Bouteloua, no genus represented by multiple species proved to be monophyletic in the phylogenies.

Situación actual de la vegetación del estado de Aguascalientes, México

Abstract: Aguascalientes es uno de los estados mas pequenos de Mexico, sin embargo, presenta un interesante mosaico de comunidades vegetales que no se habian estudiado en forma detallada. Por ello, se llevo a cabo el estudio de la vegetacion del estado de Aguascalientes, con una exploracion de campo detallada abarcando todas las comunidades vegetales del Estado y utilizando tecnicas de analisis visual de imagenes de satelite y herramientas SIG. El presente trabajo, pretende mostrar un panorama general de la vegetacion del estado de Aguascalientes, indicando los porcentajes de area cubierta de cada formacion vegetal por su afinidad climatica (templado, subtropical y xerofilo), asi como dar a conocer su situacion actual y sus expectativas de conservacion. Se determinaron 12 tipos de vegetacion con 15 subtipos locales y 50 asociaciones vegetales. La vegetacion templada es la mas ampliamente distribuida, ocupando 30.48% de la superficie total de Aguascalientes; le sigue la vegetacion xerofila, con 21.52% y por ultimo la vegetacion subtropical ocupando solo 6.58% de la superficie total del Estado. La vegetacion hidrofila solo se mantiene en algunos reservorios permanentes como presas o arroyos, ocupando 0.37% de la superficie de Aguascalientes. Se observa que la zona mas alterada del Estado es la parte subtropical, principalmente las comunidades secundarias de matorral subtropical, mientras que la mas conservada son los pastizales templados, especialmente el pastizal de montana, el cual se mantiene como comunidad primaria muy bien conservada.

Phylogeny of the Bouteloua curtipendula Complex (Poaceae: Chloridoideae) Based on Nuclear Ribosomal and Plastid DNA Sequences from Diploid Taxa

Abstract: The Bouteloua curtipendula complex (Poaceae: Chloridoideae) has been treated as a group of 12 species distributed from Canada to Argentina. Due to considerable morphological variation, putative hybridization, polyploidy (including aneuploidy), and apomixis, circumscription of and relationships among taxa have been uncertain. To infer the phylogeny of this complex, two non-coding regions, the internal transcribed spacer (nrDNA) and trnT-L-F (cpDNA), were sequenced and analyzed by maximum parsimony and maximum likelihood methods. Character-state reconstruction was carried out to test the utility of morphological characters used for species circumscription. Nuclear and plastid data revealed similar phylogenetic patterns, albeit with a lower level of resolution from the trnT-L-F sequences. Results support monophyly of the Bouteloua curtipendula complex, but not the species monophyly, except for B. triaena, which forms a strongly supported clade in both phylogenies. The origin of the Bouteloua curtipendula complex seems to be recent with low divergence between taxa. All of the morphological characters used to circumscribe species were found to be homoplasious.

Culm anatomy of bouteloua and relatives (gramineae: chloridoideae: boutelouinae)

Abstract: Transverse sections of mature flowering culms of Boutelouinae were analyzed to explore the usefulness of the culm anatomy to assess phylogenetic relationships. Fifty-five taxa were surveyed from the field and greenhouse collections. Although leaf anatomy in Boutelouinae has been shown to possess systematic utility, culm anatomy has been very little explored. In the Boutelouinae, only few traits of the culm middle internodal region with phylogenetic value, were found. Kranz structures (cells and radial chlorenchyma), number and position of the vascular bundles, and sclerenchyma girders are some culm anatomy characters that can be useful for inferring relationships at higher levels (family, tribes, genera). Culm anatomy suggests close relationships between B. eriopoda and B. eriostachya , and between B. ramosa and B. breviseta , and supports the inclusion of the satellite genera into Bouteloua . The Kranz structures and chloroplast shape appear to be the most variable features of this region of the culm.

Ecología y fitosanidad de los encinos (Quercus spp.) en la Sierra Fría, Aguascalientes, México

Abstract: A study was conducted during 2007, 2008 and 2009 to evaluate the distribution and abundance of oak species (Quercus spp), the environmental factors which affect their distribution, and the identification of pathogens and insects associated with oak decline and mortality in the Sierra Fria, Aguascalientes. To evaluate oak distribution and abundance, 60 plant inventories were made in 60 sampling sites randomly distributed within the landscape, using 600 m2 plots. To identify plant pathogens 28 transects were established, inspecting 100 oak trees per transect. To identify insects associated with oak decline, emergence traps were installed on the bole of trees that show wood boring symptoms; bole sections were taken to the lab for beetle capture. Ten oak species were identified and the variables that have influence on their distribution and abundance, were elevation, relief, aspect and physiography. As plant pathogens we identified Phellinus robustus, P. gilvus, P. everhartii, Ganoderma lucidum andHypoxylon thouarsianum, the last one being the more widely distributed. The oak borer Crioprosopus magnificus was identified, infesting live oak trees. The presence of this insect is a new report for the area of study. The information gathered in this study contributes to the management of the Sierra Fria and further studies are suggested.

A 250 plastome phylogeny of the grass family (Poaceae): topological support under different data partitions

Abstract: The systematics of grasses has advanced through applications of plastome phylogenomics, although studies have been largely limited to subfamilies or other subgroups of Poaceae Here we present a plastome phylogenomic analysis of 250 complete plastomes (179 genera) sampled from 44 of the 52 tribes of Poaceae Plastome sequences were determined from high throughput sequencing libraries and the assemblies represent over 287 Mbases of sequence data Phylogenetic signal was characterized in 14 partitions, including (1) complete plastomes; (2) protein coding regions; (3) noncoding regions; and (4) three loci commonly used in single and multi-gene studies of grasses Each of the four main partitions was further refined, alternatively including or excluding positively selected codons and also the gaps introduced by the alignment All 76 protein coding plastome loci were found to be predominantly under purifying selection, but specific codons were found to be under positive selection in 65 loci The loci that have been widely used in multi-gene phylogenetic studies had among the highest proportions of positively selected codons, suggesting caution in the interpretation of these earlier results Plastome phylogenomic analyses confirmed the backbone topology for Poaceae with maximum bootstrap support (BP) Among the 14 analyses, 82 clades out of 309 resolved were maximally supported in all trees Analyses of newly sequenced plastomes were in agreement with current classifications Five of seven partitions in which alignment gaps were removed retrieved Panicoideae as sister to the remaining PACMAD subfamilies Alternative topologies were recovered in trees from partitions that included alignment gaps This suggests that ambiguities in aligning these uncertain regions might introduce a false signal Resolution of these and other critical branch points in the phylogeny of Poaceae will help to better understand the selective forces that drove the radiation of the BOP and PACMAD clades comprising more than 999% of grass diversity

A molecular phylogeny and new subgeneric classification of Sporobolus (Poaceae: Chloridoideae: Sporobolinae)

Abstract: The grass subtribe Sporobolinae contains six genera: Calamovilfa (5 spp. endemic to North America), Crypsis (10 spp. endemic to Asia and Africa), Psilolemma (1 sp. endemic to Africa), Spartina (17 spp. centered in North America), Sporobolus (186 spp. distributed worldwide), and Thellungia (1 sp. endemic to Australia). Most species in this subtribe have spikelets with a single floret, 1-veined (occasionally 3 or more) lemmas, a ciliate membrane or line of hairs for a ligule, and fruits with free pericarps (modified caryopses). Phylogenetic analyses were conducted on 177 species (281 samples), of which 145 species were in the Sporobo - linae, using sequence data from four plastid regions (rpl32-trnL spacer, ndhA intron, rps16-trnK spacer, rps16 intron) and the nuclear ribosomal internal transcribed spacer regions (ITS) to infer evolutionary relationships and provide an evolutionary framework on which to revise the classification. The phylogenetic analysis provides weak to moderate support for a paraphyletic Sporobolus that includes Calamovilfa, Crypsis, Spartina, and Thellungia. In the combined plastid tree, Psilolemma jaegeri is sister to a trichotomy that includes an unsupported Urochondra-Zoysia clade (subtr. Zoysiinae), a strongly supported Sporobolus somalensis lineage, and a weakly supported Sporobolus s.l. lineage. In the ITS tree the Zoysiinae is sister to a highly supported Sporobolinae in which a Psilolemma jaegeri-Sporobolus somalensis clade is sister to the remaining species of Sporobolus s.l. Within Sporobolus s.l. the nuclear and plastid analyses identify the same 16 major clades of which 11 are strongly supported in the ITS tree and 12 are strongly supported in the combined plastid tree. The positions of three of these clades representing proposed sections Crypsis, Fimbriatae, and Triachyrum are discordant in the nuclear and plastid trees, indicating their origins may involve hybridization. Seven species fall outside the major clades in both trees, and the placement of ten species of Sporobolus are discordant in the nuclear and plastid trees. We propose incorporating Calamovilfa, Crypsis, Spartina, Thellungia, and Eragrostis megalosperma within Sporobolus, and make the requisite 35 new combinations or new names. The molecular results support the recognition of 11 sections and 11 subsections