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The effects of fire-related cues on seed germination and viability of Helenium aromaticum (Hook.) H.L. Bailey (Asteraceae)
No full textSe evaluó el efecto de la temperatura y el humo sobre la germinación de Helenium aromaticum; una planta anual abundante en matorrales incendiados. Encontramos que las semillas son resistentes a la alta temperatura (100°C) y al humo, pero su germinación no es estimulada por estos factores. Otras señales del fuego deben ser evaluadas
Genomic analysis of the domestication and post-Spanish conquest evolution of the llama and alpaca
No full textBackground Despite their regional economic importance and being increasingly reared globally, the origins and evolution of the llama and alpaca remain poorly understood. Here we report reference genomes for the llama, and for the guanaco and vicuna (their putative wild progenitors), compare these with the published alpaca genome, and resequence seven individuals of all four species to better understand domestication and introgression between the llama and alpaca. Results Phylogenomic analysis confirms that the llama was domesticated from the guanaco and the alpaca from the vicuna. Introgression was much higher in the alpaca genome (36%) than the llama (5%) and could be dated close to the time of the Spanish conquest, approximately 500 years ago. Introgression patterns are at their most variable on the X-chromosome of the alpaca, featuring 53 genes known to have deleterious X-linked phenotypes in humans. Strong genome-wide introgression signatures include olfactory receptor complexes into both species, hypertension resistance into alpaca, and fleece/fiber traits into llama. Genomic signatures of domestication in the llama include male reproductive traits, while in alpaca feature fleece characteristics, olfaction-related and hypoxia adaptation traits. Expression analysis of the introgressed region that is syntenic to human HSA4q21, a gene cluster previously associated with hypertension in humans under hypoxic conditions, shows a previously undocumented role for PRDM8 downregulation as a potential transcriptional regulation mechanism, analogous to that previously reported at high altitude for hypoxia-inducible factor 1 alpha. Conclusions The unprecedented introgression signatures within both domestic camelid genomes may reflect post-conquest changes in agriculture and the breakdown of traditional management practices
Revisión de la sección Brevispicae del género Sloanea (Elaeocarpaceae) en Bolivia
No full textSe presenta un catálogo comentado e ilustrado de las especies de la sección Brevispicae del género Sloanea para Bolivia, se reconocen siete especies (S. eichlerii, S. guianensis, S. obtusifolia, S. picapica, S. pubescens, S. spathulata y S. tuerckheimii). Se presenta una clave para separar las especies y para cada una se proporcionan comentarios sobre afinidades taxonómicas, material tipo, distribución, hábitat, nombres comunes y usos
Forensic identification of the keratin fibers of South American camelids by ambient ionization mass spectrometry: Vicuña, alpaca and guanaco
No full textRationale The keratin fleece of the endangered vicuna (Vicugna vicugna) commands a high value in international markets, and this trade has caused illegal poaching and a substantial decrease in vicuna populations. Morphological analysis of hairs does not have the resolution to determine the species of origin of camelid natural fibers. In addition, commerce in camelid fleece also includes the legal trade of alpaca (Vicugna pacos) and guanaco (Lama guanicoe) wool.
Methods The keratin fiber spectra of vicuna (n = 19), guanaco (n = 20) and alpaca (n = 20) were collected using X-ray fluorescence (XRF) spectrometry, Horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy and direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS). Analysis with each technique evaluated the data to determine if the three taxa could be separated using either descriptive or multivariate statistics.
Results XRF analysis showed that the elements detected and their relative concentrations were similar in all three species, whereas HATR-FTIR analysis could identify alpaca fleece but could not differentiate vicuna from guanaco. Ions detected by ambient ionization using DART-TOFMS, in either positive- or negative-ion mode, gave the best results and showed that each taxonomic group is distinctive. Multivariate analysis of the mass spectra created robust models which resolved each species (LOOCV = 99.9%). The analyses of eight validation samples were correctly assigned to the appropriate species and demonstrated the reliability of DART-TOFMS to infer taxonomic source.
Conclusions The DART-TOFMS spectra of unmodified keratin fibers infer that the chemotype of each species is heavily influenced by fatty acids, cholesterol and its analogs, and that these ions are useful in separating the fleece of vicuna, alpaca and guanaco. We posit that the etiological source of these chemotype differences is consistent with genetic modulations and is less influenced by diet. Accurate taxonomic identification of fleece is important to identify violations and assists in the protection of rare species
SISTEMA DE CRUZAMIENTO Y ESTIMACIONES EN LA EFICIENCIA DE POLINIZACIÓN SOBRE TRICHOCEREUS PASACANA (CACTACEAE) EN DOS POBLACIONES DEL NOROESTE ARGENTINO
No full textLos objetivos de este estudio fueron analizar el sistema de cruzamiento y la eficiencia de la polinización en Trichocereus pasacana y sus efectos sobre la reproducción. Se trabajó sobre dos poblaciones del noroeste Argentino, una dentro de un área protegida (Valle de Tin Tin) y otra en un sitio con marcada actividad humana de agricultura y apicultura (Cachi Adentro). El sistema de cruzamiento se analizó mediante un experimento donde se evaluó autopolinización manual, polinización cruzada manual, polinización natural y autopolinización automática. Las variables de respuesta fueron producción de frutos, producción de semillas y capacidad germinativa. La producción de frutos permite sugerir que el sistema de cruzamiento de T. pasacana es xenogámico y que la eficiencia de polinización es mayor en el área protegida. Sin embargo, las semillas provenientes de la población con actividad humana presentaron mayores tasas de germinación. Estos resultados permiten sugerir que aunque en Cachi Adentro hubo una menor producción de frutos, esta población presentó una mayor asignación de recursos para las semillas. En cambio, la población de Tin Tin produjo un mayor número de frutos pero con semillas de menor calida
Invasion of Rubus praecox (Rosaceae) is promoted by the native tree Aristotelia chilensis (Elaeocarpaceae) due to seed dispersal facilitation
No full textSeed dispersal facilitation among plant neighbours can be defined as an increase in the number, distances, and/or places reached by a plant’s seeds that is due to the presence of co-fruiting plant neighbours with which it shares seed dispersers. Many cases of this phenomenon have been described among native species and some also among introduced invasive species. Moreover, facilitation of native species recruitment by non-native fleshy-fruiting trees has been reported. Surprisingly, seed dispersal facilitation of exotic species by native species is either less common or has not been properly documented so far. Casual observation of secondary vegetation in La Araucanía Region, Chile, suggests that more individuals of exotic fleshy-fruiting bird-dispersed Rubus praecox (Rosaceae) are established under the native fleshy fruiting bird-dispersed subdioecious tree Aristotelia chilensis (Elaeocarpaceae) than under other native dry-fruiting tree species in the same areas. To assess whether these observation-suggested differences are statistically significant, two plots were sampled for interspecific associations between Rubus and Aristotelia and between Rubus and the most common dry-fruiting monoecious tree -Lomatia hirsuta (Proteaceae). The first important conclusion from this study is that invasive Rubus is substantially more common under both focal tree species than in open grasslands. Second, Rubus is associated more strongly with fleshy-fruiting Aristotelia than with dry-fruiting Lomatia in this landscape. Additionally, the frequency of Rubus is higher under Aristotelia fruiting (female or hermaphroditic) trees. Management implications are discussed
XYLEMANATOMYOF BETULAPENDULA ROTHSAPLINGS: RELATIONSHIP TO PHYSICAL VASCULAR MODELS
No full textIn conifers and diffuse-porous angiosperms, tracheary elements have an important role in structural support and water transport. In these plants it is expected that the conflict between the mechanic and hydraulic function will result in less efficient water transport at the whole plant level than the expected for plants whose conduits do not fulfil a mayor structural role (vines and ring-porous trees). Here we analyse the vascular architecture of Betula péndula saplings in order to examine predictions for diffuse-porous trees. Murray's law (conservation of Zr³) was not supported in basal tissues where the mechanical demands are be greater. Although distal portions did not depart significantly from Murray's law, lower exponents better described the relationship between consecutive levels. We found a moderate acropetal increase in conduit number, in disagreement with the model of West, Brown and Enquist, but loosely approximating Murray's law optimum. Conductive area decreased acropetally, giving a roughly conical area profile that is mechanically stable but has low transport efficiency, as predicted for diffuse-porous species. However, this trend in conductive area was uneven, the strongest reduction occurring between terminal branches and petioles. The vascular architecture of woody plants seems to respond to different constrains depending on the branching level and the mechanical functions associated with it