The genera Hypotrachyna and Remototrachyna (Parmeliaceae, Ascomycota) in northeastern Argentina

Morphological, chemical and phylogenetic examination of the lichen genera Hypotrachyna and Remototrachyna (Parmeliaceae, Ascomycota) revealed the presence of 12 species in northeastern Argentina. Three of them, H. osseoalba, H. subformosana, and R. costaricensis, are recorded for the first time for the country. The known distribution range of other eight species in the region is also extended. Distribution and comments are presented for all species, and descriptions and illustrations for most relevant records. The phylogenetic relationships of the species of Hypotrachyna and Remototrachyna reported from northeastern Argentina are analyzed

Variación del color de flores y números cromosómicos en el noroeste del área de distribución de Turnera sidoides (Turneraceae)

In the context of the evolutionary studies that are being carried out in Turners sidoides autopolyploid complex (x= 7), a systematic survey was made in the northwestern area (Bolivia) of its distribution. Six populations with salmon flowers and thirty five with yellow ones of the subsp. pinnatifida were found. The distribution of these populations is associated with climatic and spatial variables. The populations with salmon flowers live in the dry forests (Chaco Boreal Biogeographical Province), while yellow flowered populations occur in the inter-andean valleys (Boliviano-Tucumana Biogeographical Province). All the population studied are diploid. The results obtained support the allopatric diversification model of populations with yellow and salmon flowers at the diploid level, probably favoured by the orographic barriers and climatic changes that have arisen during the Andes development and Quaternary glaciations. Moreover, our analysis evidences that the north western area of T. sidoides constitutes an important centre of variation of the subsp. pinnatifida and the major centre of diploids hitherto detectedEn el marco de los estudios evolutivos que se desarrollan en el complejo autopoliploide Turnera sidoides (x= 7) se realizó un muestreo sistemático en el noroeste de su área de distribución. Se hallaron 6 poblaciones con flores de color salmón y 35 con flores amarillas de la subsp. pinnatifida. La distribución de estas poblaciones está asociada con variables climáticas y espaciales. Las poblaciones que presentan flores de color salmón viven en los bosques semiáridos (Provincia Biogeográfica del Chaco Boreal) y las de flores amarillas en los valles interandinos (Provincia Biogeográfica Boliviano-Tucumana). Todas las poblaciones analizadas son diploides. Los resultados obtenidos sustentan el modelo de diversificación alopátrica de las poblaciones con diferente color de flores a nivel diploide, probablemente favorecido por el sistema de barreras orográficas y los cambios climáticos surgidos a partir del levantamiento de los Andes y de las glaciaciones del Cuaternario. Además, el análisis evidencia que el noroeste del área de T. sidoides constituye un importante centro de variación de la subsp. pinnatifida y es el mayor centro de diploides hasta ahora detectad

Variabilidad y estructura genética de poblaciones de Schizachyrium (Poaceae, Andropogoneae) de la provincia de Corrientes (Argentina)

A fin de evaluar la utilidad de los estudios genético-poblacionales en la identificación de especies de Schizachyrium y en el papel de la hibridación natural en la evolución de dichas especies, se analizó la variabilidad y estructura genética de S. bimucronatum, S. sanguineum y S. tenerum. La identificación de bandas RAPDs y haplotipos de ADNcp exclusivos, sumados a los resultados del PCoA y AMOVA evidenciaron que dichas especies difieren genéticamente entre sí. La consistencia de estos resultados con la distinción de grupos morfológicos definidos previamente, sugiere que los análisis genético-poblacionales basados en marcadores nucleares y de cloroplastos combinados podrían contribuir a la identificación inequívoca de las especies de Schizachyrium. Asimismo, el hallazgo de algunos individuos con una proporción de sus genomas asignable a los de otras poblaciones o especies, sugiere la ocurrencia de eventos de hibridación seguida de introgresión o de poliploidización. Finalmente, los patrones de estructuración genética observados estarían relacionados a las características de los sistemas reproductivos de las especies estudiadas; mientras que la identificación de unidades evolutivas independientes en dichas especies sería de interés para el desarrollo de estrategias de conservación de las especies y de las comunidades que integran

Análisis de la producción y frecuencia de microsporas no reducidas en diploides de Turnera sidoides (Turneraceae) Analysis of the production and frequency of unreduced microspores in diploids of Turnera sidoides (Turneraceae)

Turnera sidoides es un complejo poliploide (x= 7) de hierbas rizomatosas, perennes y distilas, que incluye cinco subespecies. Debido a la alta frecuencia de poliploides en el complejo, los estudios que se llevan a cabo actualmente están orientados a la comprensión de los mecanismos involucrados en el origen y establecimiento de los mismos a fin de proveer evidencias sobre los patrones evolutivos que operan en T. sidoides. En este trabajo se investiga la producción y frecuencia de microsporas no reducidas en plantas diploides provenientes de nueve poblaciones naturales pertenecientes a cuatro subespecies de T. sidoides, mediante el análisis del rango de variación del tamaño del polen y de la constitución de las esporadas. Los resultados obtenidos mostraron que casi todas las poblaciones estudiadas producen microsporas 2x y 4x, tanto en las flores brevistilas como en las longistilas. Asimismo, el análisis realizado aportó evidencias que sustentan la poliploidización sexual como uno de los mecanismos involucrados en el origen de los poliploides dentro del complejo. Se discute, además, el papel del polen no reducido en el establecimiento y la persistencia de los poliploides formados de novo en las poblaciones diploides de la especie.Turnera sidoides is a polyploid complex (x= 7) of dystilous perennial rhizomatous herbs that includes five subspecies. Owing to the high frequency of polyploids within the complex, ongoing studies in T. sidoides are focused on the understanding of the mechanisms involved in the origin and the establishment of polyploids in order to provide evidences of the evolutionary patterns in T. sidoides. In this report we investigate the occurrence and frequency of unreduced microspores in diploid plants from nine natural populations of four subspecies of T. sidoides by analyzing the range of variation of pollen volume and the constitution of the sporads. The results obtained showed that almost all the populations studied produced 2x and 4x microspores, both in short and long-styled floral morphs. Furthermore, the analysis performed provided evidences that support the hypothesis of sexual polyploidization as one of the mechanisms involved in the origin of polyploids within this species complex. The role of unreduced pollen in the establishment and persistence of newly formed polyploids within diploid populations of T. sidoides is also discussed

Complex geographical distribution of ploidy levels in Polylepis australis (Rosaceae), an endemic tree line species in Argentina

Premise of research. The geographical distribution of ploidy levels provides insights into evolutionary pathways. For the subtropical tree line species Polylepis australis (Rosaceae), we tested the hypotheses that (1a) incidence of polyploidy is higher in the northern parts than in the southern parts of the species range due to the presence of related species that might favor hybridization (allopolyploidy), (1b) incidence of polyploidy is higher in the southern part of the range because the species here presumably reaches the limit of its environmental tolerance (autopolyploidy), and (2) ploidy levels increase with elevation, as polyploids are believed to perform better in stressful environments. Methodology. We used flow cytometry to assess the ploidy levels of 361 individuals from 27 populations across most of the distribution range of the species in two disjunct Argentinean high mountain regions. Pivotal results. The northern stands had lower ploidy levels (diploid) than the southern populations, in which we found mainly tetraploids intermixed with diploids, triploids, and a single hexaploid. We did not find any environmental correlates to the geographical distribution of ploidy levels. Conclusions. Polyploidy appears to have arisen in P. australis via autopolyploidy, either twice in different parts of the range or, more likely, once followed by long-distance dispersal. This is also supported by amplified fragment length polymorphism (AFLP) data from a previous study that confirmed higher numbers of AFLP fragments and private bands in the southern populations. The checkerboard distribution of ploidy levels in the southern Sierras de Co´ rdoba may represent a time capture of the spread of the polyploid condition. We propose that polyploidy represents a key factor to understanding the high morphological variation in P. australis and should be taken into account in ongoing reforestation activities.Fil: Kessler, Michael. University of Zurich; SuizaFil: Kühn, Andreas. Martin-Luther-University Halle-Wittenberg; AlemaniaFil: Solis Neffa, Viviana Griselda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); ArgentinaFil: Hensen, Isabell. German Centre for Integrative Biodiversity Research; Alemani

Biogeography and environmental preferences of Butia yatay (Mart.) Becc

Abstract During the Quaternary, Chaco Phytogeographic Domain (Chaco) flora in subtropical South America experienced temperature and humidity fluctuations, primarily driven by wind dynamics, leading to significant shifts in species distribution. The palm Butia yatay is endemic to the Chaco and thrives in areas characterized by a warm–rainy climate and mostly restricted to sandy soils. To investigate the current geographic distribution of suitable habitat for B. yatay while assessing the significance of soil variables, we employed two distinct algorithms in species distribution modeling (SDM). We also determined whether the distribution of B. yatay has changed since the Pleistocene and whether these changes align with previously proposed Pleistocene refugia. In the present SDMs, we considered two separate sets of predictors, one set with bioclimatic variables only and the other set with bioclimatic topographic and soil variables. Additionally, we reconstructed the historical geographic distribution of suitable habitats using bioclimatic data. Our results suggested that the primary determinants of B. yatay's current distribution include precipitation and temperature of the driest month and soil cation exchange capacity. Incorporating soil variables affected the estimated size and range of suitable areas. Projections into the past indicated similar suitable habitat distributions during interglacial periods compared with the present. During the Last Glacial Maximum, climatically suitable habitat may have shifted northward, partially overlapping with previously suggested Pleistocene refugia located between the Paraná and Uruguay Rivers. These findings indicate the main factors driving the distribution and ecology of B. yatay and enhance understanding of subtropical flora shifts during the Quaternary. The approach also may prove valuable for other studies within the Chaco

Flower colour variation and chromosome numbers in the north western distributional area of <i>Turners sidoides</i> (Turneraceae)

In the context of the evolutionary studies that are being carried out in Turners sidoides autopolyploid complex (x= 7), a systematic survey was made in the northwestern area (Bolivia) of its distribution. Six populations with salmon flowers and thirty five with yellow ones of the subsp. pinnatifida were found. The distribution of these populations is associated with climatic and spatial variables. The populations with salmon flowers live in the dry forests (Chaco Boreal Biogeographical Province), while yellow flowered populations occur in the inter-andean valleys (Boliviano-Tucumana Biogeographical Province). All the population studied are diploid. The results obtained support the allopatric diversification model of populations with yellow and salmon flowers at the diploid level, probably favoured by the orographic barriers and climatic changes that have arisen during the Andes development and Quaternary glaciations. Moreover, our analysis evidences that the north western area of T. sidoides constitutes an important centre of variation of the subsp. pinnatifida and the major centre of diploids hitherto detected</div