Andean Plant Research Articles

Keep collecting: accurate species distribution modelling requires more collections than previously thought

Aim Species distribution models (SDMs) use the locations of collection records to map the distributions of species, making them a powerful tool in conservation biology, ecology and biogeography. However, the accuracy of range predictions may be reduced by temporally autocorrelated biases in the data. We assess the accuracy of SDMs in predicting the ranges of tropical plant species on the basis of different sample sizes while incorporating real-world collection patterns and biases. Location Tropical South American moist forests. Methods We use dated herbarium records to model the distributions of 65 Amazonian and Andean plant species. For each species, we use the first 25, 50, 100, 125 and 150 records collected and available for each species to analyse changes in spatial aggregation and climatic representativeness through time. We compare the accuracy of SDM range estimates produced using the time-ordered data subsets to the accuracy of range estimates generated using the same number of collections but randomly subsampled from all available records. Results We find that collections become increasingly aggregated through time but that additional collecting sites are added resulting in progressively better representations of the species’ full climatic niches. The range predictions produced using time-ordered data subsets are less accurate than predictions from random subsets of equal sample sizes. Range predictions produced using time-ordered data subsets consistently underestimate the extent of ranges while no such tendency exists for range predictions produced using random data subsets. Main conclusions These results suggest that larger sample sizes are required to accurately map species ranges. Additional attention should be given to increasing the number of records available per species through continued collecting, better distributed collecting, and/or increasing access to existing collections. The fact that SDMs generally under-predict the extent of species ranges means that extinction risks of species because of future habitat loss may be lower than previously estimated.

Extremely Long-Lived Stigmas Allow Extended Cross-Pollination Opportunities in a High Andean Plant

High-elevation ecosystems are traditionally viewed as environments in which predominantly autogamous breeding systems should be selected because of the limited pollinator availability. Chaetanthera renifolia (Asteraceae) is an endemic monocarpic triennial herb restricted to a narrow altitudinal range within the high Andes of central Chile (3300–3500 m a.s.l.), just below the vegetation limit. This species displays one of the larger capitulum within the genus. Under the reproductive assurance hypothesis, and considering its short longevity (monocarpic triennial), an autogamous breeding system and low levels of pollen limitation would be predicted for C. renifolia. In contrast, considering its large floral size, a xenogamous breeding system, and significant levels of pollen limitation could be expected. In addition, the increased pollination probability hypothesis predicts prolonged stigma longevity for high alpine plants. We tested these alternative predictions by performing experimental crossings in the field to establish the breeding system and to measure the magnitude of pollen limitation in two populations of C. renifolia. In addition, we measured the stigma longevity in unpollinated and open pollinated capitula, and pollinator visitation rates in the field. We found low levels of self-compatibility and significant levels of pollen limitation in C. renifolia. Pollinator visitation rates were moderate (0.047–0.079 visits per capitulum per 30 min). Although pollinator visitation rate significantly differed between populations, they were not translated into differences in achene output. Finally, C. renifolia stigma longevity of unpollinated plants was extremely long and significantly higher than that of open pollinated plants (26.3±2.8 days vs. 10.1±2.2, respectively), which gives support to the increased pollination probability hypothesis for high-elevation flowering plants. Our results add to a growing number of studies that show that xenogamous breeding systems and mechanisms to increase pollination opportunities can be selected in high-elevation ecosystems.

Implications of fires on carbon budgets in Andean cloud montane forest: The importance of peat soils and tree resprouting

Fire in tropical montane cloud forests (TMCFs) is not as rare as once believed. Andean TMCFs sit immediately below highly flammable, high-altitude grasslands (Puna/Páramo) that suffer from recurrent anthropogenic fire. This treeline is a zone of climatic tension where substantial future warming is likely to force upward tree migrations, while increased fire presence and fire impacts are likely to force it downwards. TMCFs contain large carbon stocks in their peat soils and their loss through fire is a currently unaccounted for regional source of CO 2. This study, conducted in the southern Peruvian Andes (>2800 m), documents differences in live tree biomass, fine root biomass, fallen and standing dead wood, and soil organic carbon in 4 paired-sample plots (burned versus control) following the severe ground fires that occurred during the 2005 Andean drought. Peat soils contributed the most to biomass burning emissions, with lower values corresponding to an 89% mean stock difference compared to the controls (mean ± SE) (54.1 ± 22.3 vs. 5.8 ± 5.3 MgC ha −1). Contrastingly, carbon stocks from live standing trees differed by a non-significant 37% lower value in the burned plots compared to the controls, largely compensated by vigorous resprouting (45.5 ± 17.4 vs. 69.2 ± 13.4 MgC ha −1). Both standing dead trees and fallen dead wood were significantly higher in the burned plots with a three-fold difference from the controls: dead Trees 45.2 ± 9.4 vs. 16.4 ± 4.4 MgC ha −1, and ca. a 2 fold difference for the fallen dead wood: 11.2 ± 5 vs. 6.7 ± 3.2 MgC ha −1 for the burned plots versus their controls. A preliminary estimate of the regional contribution of biomass burning emissions from Andean TMCFs for the period 2000–2008, resulted in mean carbon emission rates of 1.3 TgC yr −1 (max-min: 1.8–0.8 TgC yr −1). This value is in the same order of magnitude than South American annual fire emissions (300 TgC yr −1) suggesting the need for further research on Andean forest fires. On-going projects on the region are working on the promotion of landowner participation in TMCFs conservation through REDD+ mechanism. The heart of the proposed initiative is reforestation of degraded lands with green fire breaks enriched with economically valuable Andean plant species. The cultivation of these species may contribute to reduce deforestation pressure on the Amazonian cloud forest by providing an alternative income to local communities, at the same time that they prevent the spread of fire into Manu National Park and adjacent community-held forests, protecting forest and reducing CO 2 emissions.

The best for the guest: high Andean nurse cushions of Azorella madreporica enhance arbuscular mycorrhizal status in associated plant species

Positive interactions between cushion plant and associated plants species in the high Andes of central Chile should also include the effects of fungal root symbionts. We hypothesized that higher colonization by arbuscular mycorrhizal (AM) fungi exists in cushion-associated (nursling) plants compared with conspecific individuals growing on bare ground. We assessed the AM status of Andean plants at two sites at different altitudes (3,200 and 3,600 ma.s.l.) in 23 species, particularly in cushions of Azorella madreporica and five associated plants; additionally, AM fungal spores were retrieved from soil outside and beneath cushions. 18 of the 23 examined plant species presented diagnostic structures of arbuscular mycorrhiza; most of them were also colonized by dark-septate endophytes. Mycorrhization of A. madreporica cushions showed differences between both sites (68% and 32%, respectively). In the native species Hordeum comosum, Nastanthus agglomeratus, and Phacelia secunda associated to A. madreporica, mycorrhization was six times higher than in the same species growing dispersed on bare ground at 3,600 ma.s.l., but mycorrhiza development was less cushion dependent in the alien plants Cerastium arvense and Taraxacum officinale at both sites. The ratio of AM fungal spores beneath versus outside cushions was also 6:1. The common and abundant presence of AM in cushion communities at high altitudes emphasizes the importance of the fungal root symbionts in such situations where plant species benefit from the microclimatic conditions generated by the cushion and also from well-developed mycorrhizal networks.

Land‐use and climate change effects on population size and extinction risk of Andean plants

AbstractAndean plant species are predicted to shift their distributions, or ‘migrate,’ upslope in response to future warming. The impacts of these shifts on species' population sizes and their abilities to persist in the face of climate change will depend on many factors including the distribution of individuals within species' ranges, the ability of species to migrate and remain at equilibrium with climate, and patterns of human land‐use. Human land‐use may be especially important in the Andes where anthropogenic activities above tree line may create a hard barrier to upward migrations, imperiling high‐elevation Andean biodiversity. In order to better understand how climate change may impact the Andean biodiversity hotspot, we predict the distributional responses of hundreds of plant species to changes in temperature incorporating population density distributions, migration rates, and patterns of human land‐use. We show that plant species from high Andean forests may increase their population sizes if able to migrate onto the expansive land areas above current tree line. However, if the pace of climate change exceeds species' abilities to migrate, all species will experience large population losses and consequently may face high risk of extinction. Using intermediate migration rates consistent with those observed for the region, most species are still predicted to experience population declines. Under a business‐as‐usual land‐use scenario, we find that all species will experience large population losses regardless of migration rate. The effect of human land‐use is most pronounced for high‐elevation species that switch from predicted increases in population sizes to predicted decreases. The overriding influence of land‐use on the predicted responses of Andean species to climate change can be viewed as encouraging since there is still time to initiate conservation programs that limit disturbances and/or facilitate the upward migration and persistence of Andean plant species.

Maca (L. meyenii) for improving sexual function: a systematic review

BackgroundMaca (Lepidium meyenii) is an Andean plant of the brassica (mustard) family. Preparations from maca root have been reported to improve sexual function. The aim of this review was to assess the clinical evidence for or against the effectiveness of the maca plant as a treatment for sexual dysfunction.MethodsWe searched 17 databases from their inception to April 2010 and included all randomised clinical trials (RCTs) of any type of maca compared to a placebo for the treatment of healthy people or human patients with sexual dysfunction. The risk of bias for each study was assessed using Cochrane criteria, and statistical pooling of data was performed where possible. The selection of studies, data extraction, and validations were performed independently by two authors. Discrepancies were resolved through discussion by the two authors.ResultsFour RCTs met all the inclusion criteria. Two RCTs suggested a significant positive effect of maca on sexual dysfunction or sexual desire in healthy menopausal women or healthy adult men, respectively, while the other RCT failed to show any effects in healthy cyclists. The further RCT assessed the effects of maca in patients with erectile dysfunction using the International Index of Erectile Dysfunction-5 and showed significant effects.ConclusionThe results of our systematic review provide limited evidence for the effectiveness of maca in improving sexual function. However, the total number of trials, the total sample size, and the average methodological quality of the primary studies were too limited to draw firm conclusions. More rigorous studies are warranted.

Interpretación fitosociológica de la vegetación de las lomas del desierto peruano

The vegetation of the sandy hills ("lomas") constitutes the main originality of the Peruvian and Chilean desert with a high number of endemics that shapes the vicarious associations. In this work, a phytosociological view of sandy environments of the Peruvian coastal desert is presented. According to the Braun-Blanquet method, we have made up 32 phytosociological inventories and added 138 ones from others authors. In each inventory, we have analyzed its floristic composition and ecological parameters, as altitude, soil and geomorphology. All releves were synthesized in a table to deduce the different associations, higher phytosociological units, and the distribu tion of its flora along the Peruvian coast and the Andean Cordillera. Using the Shannon-Wiener diversity index, the diversity of this flora is discussed making a comparison with historical data about the use of the territory with livestock during pre-Inca and Inca cultures, and Spanish invasion. As a result, two associations from Southern Peru -Nolanetum scaposo-spathulatae and Palauetum camanensis-weberbaueri-, two alliances -Nolanion humifusae from central Peru, and Nolanion spathulatae from the Southern Peru- and a new order -Tetragonio crystallinae-Plantaginetalia limensis- are described. In Nolanetum scaposo-spathulatae, Dictyophragnus englerianus, Leptoglossis lomana, Nolana scaposa, N. spathulata, Palaua velutina and Tetragonia vestita are the main characteristics, while in Palauetum camanensis-weberbaueri association N. scaposa and P. velutina are replaced by Palaua camanensis and P. weberbaueri. Nolanion humifusae alliance integrates species as Geranium limae, Hymenocallis amancaes, Nolana humifusa, N. latipes, Palaua rhombifolia or Villanova oppositifolia. Likewise, Cistanthe weberbaueri, Cryptantha parviflora, Hoffmannseggia miranda, Lupinus mollendoensis, Nolana confinis, N. pallidula, N. scaposa, N. spathulata, Palaua camanensis, P. velutina, P. weberbaueri, Tetragonia vestita and Weberbauerella brongniartioides are the characteristic species of Nolanion spathulatae alliance. The Tetragonio crystallinae-Plantaginetalia limensis order presents characteristic plants don't linked with eutrophic soils, as Calandrinia alba, Cryptantha limensis, Dyschoriste repens, Monnina macrostachya, Oxalis lomana, Palaua malvifolia, Pectocarya lateriflora, Plantago limensis or Tetragonia crystallina, with a distribution that claps the geographical area of the new alliances. On the other hand, the vegetation of the desert ravines is discussed in the context of the coastal river plant communities and its disturbance by the dunes. After the application of the Shannon-Wiener diversity index on the synthetic table columns, we can deduce that an increase in Andean and European ruderal species is linked to an intensive livestock activity. The transhumance between the Andes and the coast from pre-Inca times until now, produces the plant dispersion of high Andean plants toward the coast; the Spanish colonization was the origin of the presence of European plants in the "lomas" vegetation of Peru.

Modelling the responses of Andean and Amazonian plant species to climate change: the effects of georeferencing errors and the importance of data filtering

AbstractAim Species distribution models are a potentially powerful tool for predicting the effects of global change on species distributions and the resulting extinction risks. Distribution models rely on relationships between species occurrences and climate and may thus be highly sensitive to georeferencing errors in collection records. Most errors will not be caught using standard data filters. Here we assess the impacts of georeferencing errors and the importance of improved data filtering for estimates of the elevational distributions, habitat areas and predicted relative extinction risks due to climate change of nearly 1000 Neotropical plant species.Location The Amazon basin and tropical Andes, South America.Methods We model the elevational distributions, or ‘envelopes’, of 932 Amazonian and Andean plant species from 35 families after performing standard data filtering, and again using only data that have passed through an additional layer of data filtering. We test for agreement in the elevations recorded with the collection and the elevation inferred from a digital elevation model (DEM) at the collection coordinates. From each dataset we estimate species range areas and extinction risks due to the changes in habitat area caused by a 4.5 °C increase in temperature.Results Amazonian and Andean plant species have a median elevational range of 717 m. Using only standard data filters inflates range limits by a median of 433 m (55%). This is equivalent to overestimating the temperature tolerances of species by over 3 °C – only slightly less than the entire regional temperature change predicted over the next 50–100 years. Georeferencing errors tend to cause overestimates in the amount of climatically suitable habitat available to species and underestimates in species extinction risks due to global warming. Georeferencing error artefacts are sometimes so great that accurately predicting whether species habitat areas will decrease or increase under global warming is impossible. The drawback of additional data filtering is large decreases in the number of species modelled, with Andean species being disproportionately eliminated.Main conclusions Even with rigorous data filters, distribution models will mischaracterize the climatic conditions under which species occur due to errors in the collection data. These errors affect predictions of the effects of climate change on species ranges and biodiversity, and are particularly problematic in mountainous areas. Additional data filtering reduces georeferencing errors but eliminates many species due to a lack of sufficient ‘clean’ data, thereby limiting our ability to predict the effects of climate change in many ecologically important and sensitive regions such as the Andes Biodiversity Hotspot.

Bioactive metabolites from the Andean flora. Antituberculosis activity of natural and semisynthetic azorellane and mulinane diterpenoids

Natural products are recognized as an important source of new and better pharmaceuticals for the treatment of diseases such as tuberculosis. The azorellane and mulinane diterpenoids represent an interesting group of bioactive metabolites produced by Andean plants belonging to the Azorella, Mulinum, Laretia and Bolax genus. Testing of natural and semisynthetic azorellanes and mulinanes against two Mycobacterium tuberculosis strains showed that while most changes in the structure of the natural metabolites result in the loss of antituberculosis activity, methylation of the C-20 carboxyl group improves the biological activity of the corresponding derivatives.

Topological change of Andean plant–pollinator networks along an altitudinal gradient

Pollination interaction networks exhibit structural regularities across a wide range of natural environments. Long-tailed degree distribution, nestedness, and modularity are the most prevalent topological patterns found in most bipartite networks analyzed up to day. In this work we evaluate the variation of these topological properties along an altitudinal gradient. To this end, we examined four plant–pollinator networks from the Chilean Andes at 33°S, in range from 1800 to 3600 m elevation. Our results indicate that network topology is strongly and systematically affected by elevation. At increasing altitude, the number of potential visitors per plant decreased, and species’ degree distributions are closer to random expectations. On the other hand, the nested structure of mutualistic interactions systematically decreased with elevation, and network modularity was significantly higher than random expectations over the entire altitudinal range. In addition, at increasing elevations the pollination networks were organized in fewer and more strongly connected modules. Our results suggest that the severe abiotic conditions found at increased elevations translate into less organized pollination networks.

Endophytic fungi found in association with Smallanthus sonchifolius (Asteraceae) as resourceful producers of cytotoxic bioactive natural products

Smallanthus sonchifolius is a traditional Andean plant which has been cultured mainly in Brazil, Japan and New Zealand due to its medicinal properties. A study of the endophytic fungi associated to the plant was carried out in order to characterize new cytotoxic agents. Thirty two fungal strains were isolated and submitted to cultivation and extraction producing 186 extracts. Of these, 12% displayed moderate to high cytotoxic activities and were considered promising anticancer compound sources. The ethyl acetate fractions of Nigrospora sphaerica and Phoma betae liquid fermentations contained the synergistic compounds 8-hydroxy-6-methoxy-3-methylisocoumarin and (22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one which are potential compounds for drug discovery. Another isolated compound, pimara-7,15-dien-3-beta-ol diterpene is being characterized for the first time through a detailed spectroscopic analysis including GC/MS, homo- and hetero-nuclear correlated NMR experiments (HMQC, HMBC, COSY and NOEdiff) along with its optical rotation.

ENVIRONMENTAL FACTORS PREDICT ADAPTIVE PHENOTYPIC DIFFERENTIATION WITHIN AND BETWEEN TWO WILD ANDEAN TOMATOES

Environmental variation is widely viewed as a major force driving morphological change and speciation. Although many environmental attributes are potentially critical for adaptive responses within and between species, the individual and relative importance of these diverse attributes remain poorly understood. Here we combine a geographical information systems (GIS)-based analysis of environmental variation with a multipopulation analysis of phenotypic, physiological, and genetic variation, to generate and test hypotheses of environmental factors likely driving adaptive divergence within and between two wild Andean plant species. First, we document large environmental differences between population locations of the two species, and among regions within species. Second, we show evidence for inter- and intraspecific differences in genetically based phenotypic and physiological variation. Third, combining these data, we report evidence for trait-environment associations both among populations within species, and between species, that are strongly indicative of recent and rapid adaptive responses. Finally, we show that these trait-environment associations cannot be simply explained by genetic relatedness within species, reinforcing our inference that local, regional, and species-wide environmental conditions are responsible for phenotypic and physiological diversification. The strongest trait-environment associations involve temperature and precipitation gradients, suggesting these climatic factors are predominant drivers of adaptive diversification in these species.

The molecular phylogeny of Rebutia (Cactaceae) and its allies demonstrates the influence of paleogeography on the evolution of South American mountain cacti

The tropical Andes harbor a major part of the world's plant biodiversity. The montane cacti of the tribes Browningieae, Cereeae, and Trichocereeae underwent extensive radiation and thus are well suited as a model group to study the diversification of Andean plants. We reconstructed their phylogeny employing three noncoding chloroplast regions and explained it in the context of the geological history of South America. We found that the clade of cephalia-bearing cacti with naked pericarpels is centered in northeastern Brazil, whereas almost all other clades comprise Andean species. The spatial split between the clades was probably caused by the Andean uplift and the concurrent formation of intracontinental marine basins in the Tertiary. The phylogenetic reconstructions based on parsimony and Bayesian approaches do not reflect the traditional delimitation of the tribes and of the large genera. Our results suggest that Rebutia s.l. and Echinopsis s.l. are not monophyletic and that Sulcorebutia, Weingartia, and Cintia should be united into one genus. Even though this "Weingartia-complex" and the genus Gymnocalycium are similar in size and morphological diversity, Gymnocalycium has a very high molecular divergence suggesting a comparably older radiation.

Island radiation on a continental scale: exceptional rates of plant diversification after uplift of the Andes.

Species radiations provide unique insights into evolutionary processes underlying species diversification and patterns of biodiversity. To compare plant diversification over a similar time period to the recent cichlid fish radiations, which are an order of magnitude faster than documented bird, arthropod, and plant radiations, we focus on the high-altitude flora of the Andes, which is the most species-rich of any tropical mountains. Because of the recent uplift of the northern Andes, the upland environments where much of this rich endemic flora is found have been available for colonization only since the late Pliocene or Pleistocene, 2-4 million years (Myr) ago. Using DNA sequence data we identify a monophyletic group within the genus Lupinus representing 81 species endemic to the Andes. The age of this clade is estimated to be 1.18-1.76 Myr, implying a diversification rate of 2.49-3.72 species per Myr. This exceeds previous estimates for plants, providing the most spectacular example of explosive plant species diversification documented to date. Furthermore, it suggests that the high cichlid diversification rates are not unique. Lack of key innovations associated with the Andean Lupinus clade suggests that diversification was driven by ecological opportunities afforded by the emergence of island-like habitats after Andean uplift. Data from other genera indicate that lupines are one of a set of similarly rapid Andean plant radiations, continental in scale and island-like in stimulus, suggesting that the high-elevation Andean flora provides a system that rivals other groups, including cichlids, for understanding rapid species diversification.

Fotosíntesis en tres poblaciones altitudinales de la planta andina Espeletia schultzii (Compositae)

Se establece una comparación de algunos parámetros fotosintéticos: actividad Rubisco (Ribulosa 1, 5-bis-fosfato carboxilasa EC 4.1.1.39) contenidos de clorofilas, azúcares solubles totales y proteínas solubles totales y área foliar específica (AFE), en tres poblaciones altitudinales de Espeletia schultzii ubicadas a 3 100, 3 550 y 4 200 msnm. De acuerdo con el análisis de varianza la población a 4 200 m presentó una actividad Rubisco significativamente mayor que las otras dos, en cuyos casos los valores no fueron diferentes. Los contenidos de clorofila a presentan una leve tendencia a la disminución con la altura; mientras que la clorofila b se mantiene constante, razón por la cual la relación a/b (R a/b) disminuye con la elevación, aunque, las diferencias no son significativas. El contenido de azúcares en cada una de las poblaciones estudiadas (gm-2), aumenta con la elevación; las diferencias entre las poblaciones son significativas. Con relación al contenido de proteínas, no existen diferencias entre las poblaciones estudiadas. El área foliar específica (AFE) disminuye significativamente con la altura. Es probable que el incremento en la actividad Rubisco sea producido por una mayor activación de la enzima y no por el mayor contenido de proteína. Los azúcares solubles presentan incremento significativo, este hecho es probable que se encuentre asociado con la actividad Rubisco. De los cinco parámetros fotosintéticos medidos, tres presentan diferencias significativas asociadas con la altitud. Esto representa un compromiso entre una mayor actividad metabólica mantenida en un menor volumen celular.

Use of Gelatinized Maca (Lepidium peruvianum) in Early Postmenopausal Women - a Pilot Study

Objective: This double-blind, placebo-corrected clinical pilot study was aimed at assessing the use of hypocotyls of cruciferous Andean plant Maca (Lepidium peruvianum Chacon), in alleviating symptoms of menopausal discomfort experienced by women in early post menopause as measured by profiles of serum hormones: Luteinizing Hormone (LH), Follicle-stimulating Hormone (FSH), Estrogen (E2) and Progesterone (PG) and as assessed by Greene's Menopausal Index. Design: Study was conducted on 20 Caucasian healthy early-postmenopausal women volunteers during the three months period (Trial I) and on eight women during nine months period (Trial II). Hormone levels were determined in blood with a simultaneous assessment of menopausal index at the start of study, after one month use of placebo, and after two and eight months administration of 2g gelatinized Maca root powder (Maca-GO) in the form of two 500mg hard gel capsules, twice daily. Results: In comparison to placebo, after both, two and eight months administration of Maca-GO capsules to EPMW, level of FSH significantly (P<0.05) decreased with a simultaneous significant (P<0.05) increase in the LH level, resulting in significant (P<0.05) increase in both E2 and PG, after eight months of Maca-GO treatment only. There was a significant (<0.05) placebo effect resulting in an elevated PG level after one month administration of placebo capsules. Changes in hormone levels was accompanied by substantially-reduced feeling of discomfort associated with menopause, although, there was a distinctive, positive placebo effect as judged by responses to Greene's questionnaire. Conclusions: It is reasonable to suggest that Maca-GO when used in EPMW, depending on the length of use, was acting as a toner of hormonal processes as reflected by decrease in FSH and increased LH secretion, which stimulated production of both ovarian hormones, E2 and PG and resulted in a substantial reduction of menopausal discomfort felt by women participating in the study, with a distinctive placebo effect, thus, fully justifying further, more complex study on effectiveness of Maca-GO as a reliable alternative to HRT program.

Ecotypic Differentiation in Morphology and Cold Resistance in Populations of Colobanthus quitensis (Caryophyllaceae) from the Andes of Central Chile and the Maritime Antarctic

Colobanthus quitensis is one of only two vascular plant species that occur in the Antarctic islands. We evaluated morphological and physiological traits and survival after freezing in individuals of C. quitensis collected in two populations: one from the Andes of central Chile and the other from the maritime Antarctic. We addressed whether these populations are ecotypes in terms of shoot morphology and physiology, and cold resistance. We also evaluated genetic differentiation at the internal transcribed spacer (ITS) regions. Under controlled growing conditions, Andean plants had longer and narrower leaves and longer peduncles. However, shoot biomass was similar in both populations. There was a 1.17% sequence divergence of ITS regions between populations. Survival to freezing at temperatures from 0° to −16°C was not different in nonacclimated plants. After cold-acclimation at 4°C, freezing tolerance was greater in Antarctic plants. Both Andean and Antarctic plants increased soluble sugars with increasing acclimation time, but it did not differ between populations. Shoot water content decreased with acclimation time in both populations, but Antarctic plants maintained slightly higher water contents after cold exposure. Shoot growth did not differ during acclimation. The studied populations of C. quitensis represent different morphological and cold resistant ecotypes despite their genetic similarity. However, the mechanistic basis of the higher survival to freezing of Antarctic plants was not elucidated.

Antioxidant activity of extracts from the leaves of Smallanthus sonchifolius.

Yacon ( Smallanthus sonchifolius, Asteraceae) is a native Andean plant, cultivated for its tubers throughout South America. The leaves are used in folk medicine as a medicinal tea for hypoglycemia. This paper describes the antioxidant activity of various extracts from S. sonchifolius leaves for their content of phenolic components. The dried leaves were extracted in several ways. Two fractions were selected for their high content of phenolic compounds and analyzed by RP-HPLC. The antioxidant activity of these fractions was tested in 1,1-diphenyl-2-picrylhydrazyl (DPPH) and xanthine/XOD superoxide radical scavenging assays, as inhibition of lipoperoxidation of subcellular membranes and as protective activity against oxidative injury of rat hepatocytes in primary cultures. The presence of protocatechuic (2.5 and 0.12 mg/g), chlorogenic (9.9 and 1.7 mg/g), caffeic (14.7 and 0.09 mg/g) and ferulic (traces) acids were determined in the two fractions. Both fractions showed potent antioxidant activity in DPPH (IC(50) = 16.1 +/- 3.4 and 24.3 +/- 2.7 mg/ml) and xanthine/XOD superoxide radical scavenging (42.0 +/- 20.3 and 34.3 +/- 11.4 SOD equivalents (U/mg)) tests, they inhibited the lipoperoxidation of rat liver subcellular membranes and they protected rat hepatocytes against oxidative injury. Our results may predetermine the use of S. sonchifolius leaves in human diet as a potential remedy in the prevention of chronic diseases caused by radicals, e. g., arteriosclerosis.

Madreporanone, a Unique Diterpene with a Novel Skeleton from Azorella madreporica.

A unique diterpene 1, was isolated from the altiplane Andean plant Azorella madreporica Clos (Apiaceae). The structure and stereochemistry were established by spectral methods and molecular mechanics calculations. The compound possesses a novel hydrocarbon skeleton for which we suggest the name madreporane.

The elevational gradient of Andean plant endemism: varying influences of taxon‐specific traits and topography at different taxonomic levels

AbstractAim Little is known about the elevational gradient of plant endemism. It is mostly assumed that patterns are determined by topographical factors such as area of elevational belts and degree of habitat fragmentation, but comparative studies of different plant taxa along the same elevational gradient are lacking. The aim was to compare the elevational patterns of plant endemism of the entire flora and selected families and genera in a search for commonalities.Methods The elevational patterns of endemism for the entire Ecuadorean vascular plant flora, for twenty‐seven selected families, and for twenty‐four selected genera based on the Catalogue of Vascular Plants of Ecuador were analysed.Results Elevational patterns of endemism were non‐random at all taxonomic levels but there was no common elevational pattern. Rather, the study groups showed a wide variety of independent patterns at all taxonomic levels. Most groups had hump‐shaped patterns with maxima at different elevations and mostly at the same or at higher elevations than the maxima of species richness. The overall flora showed highest endemism in the narrowest and most fragmented elevational belts, presumably because of the consequent fragmentation of species populations.Main conclusions Patterns of endemism appear to be influenced both by taxon‐specific ecological traits (e.g. life form, reproduction, dispersal, demography, spatial population structure, competitive ability) in their specific interaction with historical processes and by environmental factors such as topographical fragmentation. The degree to which these influences become visible along the elevational gradient are determined by which combination of species is analysed: for a given genus or family, taxon‐specific traits dominate the patterns, for the entire flora taxon‐specific patterns are blurred by averaging and the signal of topography emerges. Beyond the elevational gradient as such, this study shows that the frequently stated assumption that given biogeographical settings lead to similar patterns of endemism among different taxa is wrong.