Sistema reproductivo de Trichopetalum plumosum (Ruiz & Pav.) J.F. Macbr. (Asparagaceae), geófita endémica de Chile

The breeding system of the geophyte endemic to Chile Trichopetalum plumosum (Ruiz & Pav.) J.F. Macbr. (Asparagaceae) was evaluated with five controlled pollination treatments (agamospermy, autonomous autogamy, self-pollination, crosspollination and natural / control). Emasculated and unpollinated flowers did not produce fruits, therefore, this is a nonapomictic species and needs pollen for seed production. Fruit production via cross and natural pollination treatments were high with 70.0 and 90.9%, respectively. Despite the low production via self-pollination (43.3%), autonomous autogamy (90.0%) achieved high values as cross and natural pollination treatments. The results for the mean number of seeds per flower were similar to fruiting. However, analysis of the mean number of seeds per fruit did not show significant differences. These results indicate that the population of T. plumosum is self-compatible with a high capacity for autonomous autogamy. It could be possible that autonomous autogamy of this species occurs when the stamens of the flowers move toward the stigma while they close and wither at the end of the day, corresponding to a delayed selfing mode.En este estudio se evaluó el sistema reproductivo de Trichopetalum plumosum (Ruiz & Pav.) J.F. Macbr. (Asparagaceae), una geófita endémica de Chile. Se realizaron cinco tratamientos de polinización controlada (agamospermia, autogamia autónoma, autopolinización, polinización cruzada y natural / control). Ninguna de las flores emasculadas y sin polinizar produjo frutos, lo que indica que esta especie no es apomíctica y, por lo tanto, necesita polen para la producción de semillas. La fructificación en el tratamiento de polinización cruzada (70,0%) fue alta y similar al porcentaje alcanzado a través de la polinización natural (90,9%). A pesar del porcentaje menor en la prueba de autopolinización (43,3%), la autogamia autónoma (90,0%) se acercó a los altos valores alcanzados en los dos primeros tratamientos mencionados. Para el promedio de semillas por flor tratada, los resultados concuerdan con los de fructificación. Sin embargo, al evaluar el número promedio de semillas por fruto formado, los tratamientos no mostraron diferencias significativas. Los resultados indican que la población de T. plumosum es autocompatible con una alta capacidad para la autogamia autónoma. Se sugiere que esta última se produce por el movimiento de los estambres hacia el estigma al final del día a medida que las flores se marchitan y cierran, correspondiendo a un modo de autofecundación tardía

Senda Darwin Biological Station: Long-term ecological research at the interface between science and society

Indexación: Web of Science; Scielo.La Estación Biológica Senda Darwin (EBSD) constituye un centro de investigación inmerso en el paisaje rural del norte de la Isla de Chiloé (42º S), donde fragmentos del bosque siempreverde original coexisten con praderas de uso ganadero, turberas de Sphagnum, matorrales sucesionales, plantaciones de Eucalyptus y otras formaciones de origen antropogénico. Desde 1994 hemos realizado estudios de largo plazo centrados en algunas especies de plantas (e.g., Pilgerodendron uviferum D. Don) y animales (e.g., Aphrastura spinicauda Gmelin, Dromiciops gliroides [Thomas]) catalogados como amenazados o escasamente conocidos y en ecosistemas nativos de importancia regional y global (e.g., turberas de Sphagnum, bosque Valdiviano y Nordpatagónico). Las investigaciones han considerado las respuestas de las especies y de los ecosistemas frente al cambio antropogénico del paisaje y cambio climático, así como los efectos de diferentes formas de manejo. Este escenario es semejante al de otras regiones de Chile y Latinoamérica lo que da generalidad a nuestros resultados y modelos. En este período, investigadores asociados a la EBSD han producido más de un centenar de publicaciones en revistas nacionales e internacionales y 30 tesis de pre y postgrado. Entendiendo el papel clave de los seres humanos en los procesos ecológicos de la zona rural, la EBSD ha desarrollado un programa de educación ecológica y vinculación del avance científico con la sociedad local y nacional. La integración de la EBSD a la naciente red de Sitios de Estudios Socio-Ecológicos de Largo Plazo en Chile consolidará y fortalecerá la investigación básica y aplicada que realizamos para proyectarla hacia la siguiente década.Senda Darwin Biological Station (SDBS) is a field research center immersed in the rural landscape of northern Chiloé island (42º S), where remnant patches of the original evergreen forests coexist with open pastures, secondary successional shrublands, Sphagnum bogs, Eucalyptus plantations and other anthropogenic cover types, constituting an agricultural frontier similar to other regions in Chile and Latin America. Since 1994, we have conducted long-term research on selected species of plants (e.g., Pilgerodendron uviferum) and animals (e.g., Aphrastura spinicauda, Dromiciops glirioides) that are considered threatened, poorly known or important for their ecological functions in local ecosystems, and on ecosystems of regional and global relevance (e.g., Sphagnum bogs, North Patagonian and Valdivian rain forests). Research has assessed the responses of species and ecosystems to anthropogenic land-use change, climate change, and the impact of management. During this period, more than 100 scientific publications in national and international journals, and 30 theses (graduate and undergraduate) have been produced by scientists and students associated with SDBS. Because of our understanding of the key role that humans play in ecological processes at this agricultural frontier, since the establishment of SDBS we have been committed to creative research on the communication of science to society and ecological education. The integration of SDBS to the nascent Chilean network of long-term socio-ecological research will consolidate and strengthen basic and applied research to project our work into the next decade.http://ref.scielo.org/vbm4r

Global urban environmental change drives adaptation in white clover

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

Genetic Diversity and Population Structure of Jubaea chilensis, an Endemic and Monotype Gender from Chile, Based on SNP Markers

Jubaea chilensis (Molina) Baill., also named Chilean palm, is an endemic species found in the coastal area of Mediterranean sclerophyllous forest in Chile. It has a highly restricted and fragmented distribution along the coast, being under intense exploitation and anthropogenic impact. Based on 1038 SNP markers, we evaluated the genetic diversity and population structure among six J. chilensis natural groups encompassing 96% of the species distribution. We observed low levels of genetic diversity, a deficit of heterozygotes (mean HE = 0.024; HO = 0.014), and high levels of inbreeding (mean FIS = 0.424). The fixation index (FST) and Nei’s genetic distance pairwise comparisons indicated low to moderate structuring among populations. There was no evidence of isolation by distance (r = −0.214, p = 0.799). In the cluster analysis, we observed a closer relationship among Culimo, Cocalán, and Candelaria populations. Migration rates among populations were low, except for some populations with moderate values. The K value that best represented the spatial distribution of genetic diversity was ∆K = 3. Habitat fragmentation, deterioration of the sclerophyllous forest, lack of long-distance dispersers, and a natural regeneration deficit may have driven inbreeding and low levels of genetic diversity in the palm groves of J. chilensis. Although extant populations are not at imminent risk of extinction, the rate of inbreeding could increase and migration could decrease if the effects of climate change and human impact become more acute

Karyological study in fifteen Leucocoryne taxa (Alliaceae)

The karyotype of fifteen Leucocoryne taxa was studied, assessing characteristics such as chromosome morphology and size, secondary constriction location, and asymmetry level. Two groups of Leucocoryne taxa were described based on chromosome number (2n = 10 and 2n = 18) and karyotype asymmetry. The haploid karyotype formula for the group 2n = 10 was 3m + 2st (or 2t), whereas for the group 2n = 18 was 7m + 2st (or 2t). Such results corroborate the karyotype descriptions previously carried out for some taxa of the genus. Leucocoryne taxa showed a high resemblance in chromosome morphology, but inter-specific differences were found in mean chromosome size. These data and previous studies based on gross chromosome morphology support Crosa's hypothesis, which suggests that the cytotype 2n = 10 is diploid and perhaps ancestral, whereas that the cytotype 2n = 18 is tetraploid but with an additional chromosome fusion being probably a derived status. © 2012 Versita Warsaw and Springer-Verlag Wie

Karyological study in fifteen Leucocoryne taxa (Alliaceae)

The karyotype of fifteen Leucocoryne taxa was studied, assessing characteristics such as chromosome morphology and size, secondary constriction location, and asymmetry level. Two groups of Leucocoryne taxa were described based on chromosome number (2n = 10 and 2n = 18) and karyotype asymmetry. The haploid karyotype formula for the group 2n = 10 was 3m + 2st (or 2t), whereas for the group 2n = 18 was 7m + 2st (or 2t). Such results corroborate the karyotype descriptions previously carried out for some taxa of the genus. Leucocoryne taxa showed a high resemblance in chromosome morphology, but inter-specific differences were found in mean chromosome size. These data and previous studies based on gross chromosome morphology support Crosa's hypothesis, which suggests that the cytotype 2n = 10 is diploid and perhaps ancestral, whereas that the cytotype 2n = 18 is tetraploid but with an additional chromosome fusion being probably a derived status

Phylogenetic reconstruction of the genus Triptilion (Asteraceae, Nassauvieae) based on nuclear and chloroplast DNA sequences

The genus Triptilion is endemic to central Chile, the Mendoza Province and western Patagonia in Argentina. It is currently composed of seven species: T. achilleae, T. benaventii, T. berteroi, T. capillatum, T. cordifolium, T. gibbosum, and T. spinosum. The main objectives of this paper were to determine the phylogenetic relationships of species of Triptilion. We also traced the evolution of annual and perennial life-forms. Historically a close relationship has been described between genera Triptilion and Nassauvia. Phylogenetic analysis of the genus Triptilion and more closely related genera was undertaken using two nuclear (ITS, ETS) and two chloroplast (trnL-F, rpl32-trnL) markers. The topology of the Bayesian inference tree shows that the genus Triptilion is paraphyletic, because Nassauvia lagascae, the only representative of Nassauvia section Caloptilium grouped with T. achilleae, Clade I. The other species of Triptilion form two clades: Clade II composed of T. cordifolium and T. gibbosum and Clade III that includes T. benaventii, T. berteroi, T. capillatum, and T. spinosum. The genus Triptilion originated and diverged during the Miocene. The results of the life history reconstructions indicate that the common ancestor of Triptilion and Nassauvia was perennial. The annual habit appears to be derived in Triptilion. The life-form of the common ancestor of Triptilion was ambiguous; it may have been annual or perennial.FONDECYT initiation 11130299 ICM-MINECON P05-002-IEB PBF-2

Factores abióticos que influencian la germinación de seis especies herbáceas de la zona árida de Chile Abiotic factors effects influencing the germination of six herbaceous species of Chilean arid zone

La zona árida del norte de Chile presenta un clima seco que impide la emergencia masiva de especies vegetales, excepto cuando se producen escasas e irregulares precipitaciones que modifican las características de aridez y estimulan la germinación de semillas. Los principales factores externos que modifican estructuras y condiciones internas de las semillas son el tiempo de hidratación, iluminación, temperatura y escarificación. En este trabajo se abordaron dos interrogantes: (a) ¿la germinación de semillas de seis especies de zonas áridas es regulada por diferentes factores externos o presentan respuestas comunes a una combinación de estímulos? y (b) ¿existe correspondencia entre las condiciones germinativas establecidas en laboratorio y las determinadas in situ? Para resolver estas interrogantes se sometieron seis especies herbáceas endémicas y nativas del norte de Chile (Cistanthe salsoloides, Leucocoryne purpurea, Pasithea coerulea, Placea amoena, Schizanthus litoralis y Trichopetalum plumosum) a dos experimentos germinativos con combinaciones factoriales de tiempo de hidratación, temperatura e iluminación. Solo S. litoralis fue sometido a un experimento adicional de escarificación y deshidratación. Los resultados determinaron que todas las especies en estudio presentaron respuestas germinativas comunes frente a determinados factores externos, con una máxima germinación al sobrepasar un umbral de 96 h de hidratación y permanecer a niveles de temperatura de 10 a 25 ºC. La respuesta frente a iluminación fue especie dependiente. Schizanthus litoralis solo responde a estímulos externos previo a ser escarificada su semilla. Además, se determinó que existe concordancia entre los factores germinativos determinados en laboratorio y las condiciones naturales de germinación. Por lo tanto, las semillas de las especies en estudio presentan umbrales germinativos semejantes, y las técnicas de germinación en laboratorio deben ser determinadas por las características ambientales del lugar de procedencia y de la época de germinación naturalThe arid zone of northern Chile has a dry climate that prevents the massive emergency of plant species. The exception to this general trend arises when scarce and irregular rainfall events occur, modify the environmental humidity, and stimulate the germination of seeds. The main external factors that modify the internal nature of the seeds are the hydration time, light, temperature and scarification. In this work two questions were addressed: (a) is the germination of seeds of arid zones regulated by independent external factors or by a combined array of stimuli? and (b) do exist correspondence between laboratory and in situ germinative conditions?. Seeds of six native and endemic herbaceous species of the north of Chile (Cistanthe salsoloides, Leucocoryne purpurea, Pasithea coerulea, Placea amoena, Schizanthus litoralis y Trichopetalum plumosum) were subjected to two germination experiments, with factorial combinations of hydration time, temperature, light, dehydration and scarification. Schizanthus litoralis, was subjected to an aditional scarification-dehydration experiment (experiment 3). Results showed a common response of all the species in study to certain external factors. Maximum germination percentages were reached when exceeding a threshold of 96 h of hydration and at temperatures of 10 to 25 ºC. Light response was species-dependent. Agreement was found between the germinative conditions determined in laboratory and natural conditions of germination. Therefore, the seeds of plant species of arid zones display similar germinative thresholds and the techniques of germination in laboratory must be determined by the environmental characteristics of the place of origin and the time of natural germinatio