647 research outputs found
Veränderung genetischer Variationsmuster von Waldbäumen unter Gesichtspunkten des Klimawandels
No full textThe hyperdominant tropical tree Eschweilera coriacea (Lecythidaceae) shows higher genetic heterogeneity than sympatric Eschweilera species in French Guiana
No full textBackground and aims – The evolutionary history of Amazonia’s hyperabundant tropical tree species, also known as “hyperdominant” species, remains poorly investigated. We assessed whether the hyperdominant Eschweilera coriacea (DC.) S.A.Mori (Lecythidaceae) represents a single genetically cohesive species, and how its genetic constitution relates to other species from the same clade with which it occurs sympatrically in French Guiana.Methods – We sampled 152 individuals in nine forest sites in French Guiana, representing 11 species of the genus Eschweilera all belonging to the Parvifolia clade, with emphasis on E. coriacea. Samples were genotyped at four simple sequence repeat (SSR) markers. We delimited gene pools, i.e., genetically coherent putative taxa, using STRUCTURE software and principal component analysis. We compared the genetic assignment of individuals with their morphological species determination and estimated genetic diversity and differentiation for gene pools and species. We also estimated genome size using flow cytometry.Key results – SSR profiles commonly displayed up to four alleles per genotype, suggesting that the investigated Eschweilera species bear a paleopolyploid signature. Flow cytometry suggested that the studied species are diploid with haploid genome sizes of 871–1046 Mbp. We detected five gene pools and observed a good correspondence between morphological and genetic delimitation for Eschweilera sagotiana Miers and the undescribed morphospecies E. sp. 3 (which resembles E. grandiflora (Aubl.) Sandwith), and to a lesser extent for E. decolorans Sandwith and E. micrantha (O.Berg) Miers. Eschweilera coriacea was the most genetically diverse species and included individuals assigned to each gene pool. Conclusions – We found no conclusive evidence for cryptic species within E. coriacea in French Guiana. SSRs detected fewer gene pools than expected based on morphology in the Parvifolia clade but discriminated evolutionary relationships better than available plastid markers. A positive trend between demographic abundance of species and allelic richness illustrates that hyperdominants may have a high evolutionary potential. This hypothesis can be tested using more powerful genomic data in combination with tree phenotypic trait variation and characterization of niche breadth, to enhance our understanding of the causes of hyperdominance in Amazonian trees
Environmental effects on fine-scale spatial genetic structure in four Alpine keystone forest tree species
No full textDo silver fir woolly adelgids (Dreyfusia nordmannianae) facilitate pathogen infestation with Neonectria neomacrospora on Christmas trees (Abies nordmanniana)?
No full textThe Natural Evolutionary Potential of Tree Populations to Cope with Newly Introduced Pests and Pathogens—Lessons Learned From Forest Health Catastrophes in Recent Decades
No full textGenetic diversity and fine-scale spatial genetic structure of the near-threatened Pinus gerardiana in Gardiz, Afghanistan
No full textBackground and aims – Chilgoza pine (Pinus gerardiana) is a near-threatened tree species from the north-western Himalayas. This species is the economically most important pine in Afghanistan because of its edible nuts; however, its distribution range is disjunct and restricted to a few isolated regions. The IUCN lists Chilgoza as a near threatened species because of overexploitation of its nuts and a declining population trend. This research is the first in-depth analysis of the genetic variability and structure of Chilgoza in Afghanistan using microsatellite markers. Material and methods –We tested cross-amplification of 44 SSR markers developed for pine species. Eight polymorphic EST-SSRs were genotyped in a natural Chilgoza population in Gardiz, Afghanistan. To evaluate the genetic diversity, fine-scale spatial genetic structure (SGS), signatures of bottleneck events, and the effective population size, 191 trees were sampled and genotyped. Based on the diameter at breast height, individuals were classified as young or old trees. Key results – Genetic variation in the whole population was moderate. For individual markers, He ranged from 0.130 to 0.515 (mean = 0.338) and Ho from 0.118 to 0.542 (mean = 0.328). The expected heterozygosity in young trees was slightly lower than in old trees. The SGS was stronger for young trees (Sp = 0.0100) than for old trees (Sp = 0.0029). Heterozygosity excess analysis detected no recent population size reduction, but the M ratio revealed an ancient and prolonged bottleneck in the Chilgoza population. Conclusion – Identification of suitable EST-SSRs for future studies of natural Chilgoza populations provides important tools for the conservation of the species. Despite the moderate genetic variation in Gardiz, scarcity of natural regeneration is likely to reduce the genetic variation and adaptability in future generations. Our results indicated a slight decrease in genetic diversity and stronger SGS in young trees calling for conservation measures fostering natural regeneration
Characterisation of nuclear microsatellite markers for Fraxinus excelsior L. and their transferability to six related species
No full textCommon ash (Fraxinus excelsior L.) is an economically and eco-logically important tree species in Europe acutely threatened by ash dieback. Here, we present a new set of Simple Sequence Repeat markers for F. excelsior and six related ash species based on published in silico designed primers. Forty SSR markers, mainly from genic regions, were tested for amplification and polymorphism and characterized in two ash populations in Germany. Transferability of polymorphic markers to six related Fraxinus species (F. angustifolia, F. ornus, F. quadrangulata, F. pennsylvanica, F. americana and F. biltmoreana) was also assessed. Eighteen markers, predominantly from genic regions including three markers closely linked to candidate genes for ash dieback, were successfully amplified and polymorphic in F. excelsior, of which between 10 to 17 were transferable to one of the six related species. High genetic diversity was found in the two ash populations (Na = 7.8 and 6.9, He = 0.71 and 0.68), while low genetic differentiation between populations (FST = 0.025) was observed. The newly characterised SSR markers extend the set of genetic markers available for F. excelsior and six other ash species for future studies on the genetic diversity and structure of ash populations
Birgit Becker / David Reimer (Hrsg.): Vom Kindergarten bis zur Hochschule. Die Generierung von ethnischen und sozialen Disparitäten in der Bildungsbiographie. Wiesbaden: VS Verlag für Sozialwissenschaften 2009 (316 S.) [...] [Sammelrezension]
No full textSammelrezension von: 1. Birgit Becker / David Reimer (Hrsg.): Vom Kindergarten bis zur Hochschule. Die Generierung von ethnischen und sozialen Disparitäten in der Bildungsbiographie. Wiesbaden: VS Verlag für Sozialwissenschaften 2009 (316 S.; ISBN 978-3-5311-6224-9; 39,95 EUR); 2. Heinz-Hermann Krüger / Ursula Rabe-Kleberg / Rolf-Torsten Kramer / Jürgen Budde (Hrsg.): Bildungsungleichheit revisited. Bildung und soziale Ungleichheit vom Kindergarten bis zur Hochschule. Wiesbaden: VS Verlag für Sozialwissenschaften 29,9 (324 S.; ISBN 978-3-5311-6672-8; 29,95 EUR)
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