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Presentación De Powerpoint Endemics from the Chihuahuan Desert with edaphic affinity in gypsum soils: a case of phylogeography and genetic diversity studies for Tidestromia (Amaranthaceae). Ivonne Sánchez-del Pino Centro de Investigación Científica de Yucatán, A.C. Introduction Herbarium specimens were made from collected material. Floral The genus Tidestromia consists of eight species. It is unique within parts were preserved in 70 % ethanol for floral ontogeny studies. In Gomphrenoideae (Amaranthaceae) in that it shows an edaphic addition, leaves were dried in silica for future molecular research. affinity for calcareous, gypseous, and saline soils in the Chihuahuan Five of the eight species of Tidestromia were collected in the field. Desert. The genus has evolved in the deserts of the American Images of endemic species are represented here (Figure 3). Southwest and Mexico (Figure 1). Recent studies have focused on the taxonomy and systematics of Tidestromia. These works have highlighted various taxonomic problems in the genus but have not A B yet defined the diversity within the species. Therefore, it is necessary to perform population genetics and phylogeographic studies to analyse and clarify the current diversity of these taxa. A B C D Figure 1. Morphology and distribution of Tidestromia. A. Inflorescence. B. Range of distribution. Objectives Figure 3. Endemics of Tidestromia. A. T. valdesiana. B. T. carnosa. C. T. • To clarify the taxonomic circumscription of three problematic rhizomatosa. D. T. tenella. species of Tidestromia: T. carnosa, T. lanuginosa, and T. Thirty-six DNA extractions were obtained and 129 DNA sequences suffruticosa. of trnL-F and psbJ-petA have been edited and aligned (Figure 4) to • To determine the historical processes that have influenced their be processed for phylogeographic studies as part of graduate and current geographic distribution and genetic variation. undergraduate students projects. Methods A Taxon sampling. In this study fresh material was collected from several populations of Tidestromia in Mexico. Molecular study. Sequences of nuclear (ITS) and chloroplast B molecular markers (trnL-F, psbJ-petA, and rpl32-trnL) have been generated for five individuals of each population to understand the diversity and population genetic structure, as well as, the ancestral haplotypes, using phylogeographic techniques. Figure 4. Molecular work. A. DNA extractions in agarose gel. B. Alignment of Morphological study. Gross morphology comparisons for each trnL-F intron. herbarium specimen and observations in the field will be analysed to Future work describe each species of Tidestromia. To complete our goals it is necessary to conduct field work in the USA, in the states of California, Utah, Arizona, Colorado, New Results Mexico, Kansas, Texas, Missouri and Illinois. In addition, field In this study fresh material was collected from 36 populations, work is required in the Mexican states of Zacatecas, Durango, representing five species of Tidestromia, collected from the Mexican Sinaloa, Sonora and Baja California to include the entire range of states of Coahuila, Chihuahua, Nuevo León and San Luis Potosí distribution of these species, in order for a circumscription to be (Figure 2), which form part of the Chihuahuan Desert. established. The molecular work is still in progress for the material from Mexican states. Acknowledgments This study was supported by the Consejo Nacional de Ciencia y Tecnología in Mexico City (CONACYT) Ciencia Básica- CONACYT-2014 under the grant number 243153 and The Percy Sladen Memorial Fund. Selected References Sánchez-del Pino I. 2001. Sistemática del Género Tidestromia Standl. (Amaranthaceae). MSc. Thesis, Universidad Nacional Autónoma de México, México. Figure 2. Species of Tidestromia collected in the field. ☐ T. carnosa. ☐ T. lanuginosa. ☐ T. suffruticosa. ☐ T. tenella. ☐ T. valdesiana. Sánchez-del Pino I, Flores Olvera H. 2006. Phylogeny of Tidestromia (Amaranthaceae, Gomphrenoideae) based on morphology. Systematic Botany 31: 689–671..
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