25 research outputs found
Drought-Adaptation Potential in Fagus sylvatica: Linking Moisture Availability with Genetic Diversity and Dendrochronology
<div><h3>Background</h3><p>Microevolution is essential for species persistence especially under anticipated climate change scenarios. Species distribution projection models suggested that the dominant tree species of lowland forests in Switzerland, European beech (<em>Fagus sylvatica</em> L.), might disappear from most areas due to expected longer dry periods. However, if genotypes at the moisture boundary of the species climatic envelope are adapted to lower moisture availability, they can serve as seed source for the continuation of beech forests under changing climates.</p> <h3>Methodology/Principal Findings</h3><p>With an AFLP genome scan approach, we studied neutral and potentially adaptive genetic variation in <em>Fagus sylvatica</em> in three regions containing a dry and a mesic site each (<em>n</em><sub>ind.</sub>â=â241, <em>n</em><sub>markers</sub>â=â517). We linked this dataset with dendrochronological growth measures and local moisture availabilities based on precipitation and soil characteristics. Genetic diversity decreased slightly at dry sites. Overall genetic differentiation was low (<em>F</em><sub>st</sub>â=â0.028) and Bayesian cluster analysis grouped all populations together suggesting high (historical) gene flow. The Bayesian outlier analyses indicated 13 markers with three markers differing between all dry and mesic sites and the others between the contrasting sites within individual regions. A total of 41 markers, including seven outlier loci, changed their frequency with local moisture availability. Tree height and median basal growth increments were reduced at dry sites, but marker presence/absence was not related to dendrochronological characteristics.</p> <h3>Conclusion and Their Significance</h3><p>The outlier alleles and the makers with changing frequencies in relation to moisture availability indicate microevolutionary processes occurring within short geographic distances. The general genetic similarity among sites suggests that âpreadaptiveâ genes can easily spread across the landscape. Yet, due to the long live span of trees, fostering saplings originating from dry sites and grown within mesic sites might increase resistance of beech forests during the anticipated longer dry periods.</p> </div
Estimation of Fagus sylvatica L mating system parameters in natural populations
The mating system of beech (Fagus sylvatica L) was investigated using polymorphism at 4 allozyme loci and the multilocus model of Ritland and Jain (1981). Beech appears to be a highly outcrossing species: the outcrossing rate ranges from 0.94 to 1. No significant differences were found in outcrossing rates according to environmental factors or among or within trees. Comparison of single-locus and multilocus estimates indicated that little or no inbreeding occurred. Outcross pollen pool was not homogeneous and heterogeneity in pollen allelic frequencies was observed even among nearby trees. A possible explanation may be the temporal variability of the pollen pool due to variation in flowering time and to matings between phenologically synchronous trees.Estimation des paramĂštres du mode de reproduction de Fagus sylvatica L. Le mode de reproduction du hĂȘtre (Fagus sylvatica) a Ă©tĂ© Ă©tudiĂ© Ă l'aide de 4 marqueurs alloenzymatiques (GOT1, MDH1, SOD1 et IDH1) et du modĂšle multilocus de Ritland etJain (1981) dans 4 populations françaises : l'une en forĂȘt d'Issaux dans les PyrĂ©nĂ©es-Atlantiques, les trois autres dans le massif de l'Aigoual (La SerreyrĂšdes, Plo du Four et Sommet) (tableau I). Dans la forĂȘt d'Issaux, 3 parcelles prĂ©sentant des physionomies diffĂ©rentes ont Ă©tĂ© Ă©tudiĂ©es : une parcelle Ă forte densitĂ© (forĂȘt), une autre situĂ©e en lisiĂšre de forĂȘt et la troisiĂšme formĂ©e d'arbres isolĂ©s. Les questions abordĂ©es dans cette Ă©tude sont les suivantes : i) quel est le taux d'autofĂ©condation du hĂȘtre en conditions naturelles ? ii) existe-t-il des variations de ce taux dans l'espace et dans le temps ? iii) existe-t-il une hĂ©tĂ©rogĂ©nĂ©itĂ© du pollen Ă l'intĂ©rieur des populations ? Le hĂȘtre est une espĂšce hautement allogame : le taux d'allofĂ©condation est compris entre 0,94 (Aigoual) et 1 (Issaux) (tableau II). Ces estimations correspondent Ă des taux d'autofĂ©condation infĂ©rieurs Ă la valeur moyenne (13%) calculĂ©e Ă partir des observations de Nielsen et Schaffalitzky-de-Muckadell (1954). Aucune diffĂ©rence significative n'a Ă©tĂ© mise en Ă©vidence selon les variations des facteurs de l'environnement entre les taux d'allofĂ©condation observĂ©s. Ce taux ne varie pas non plus significativement d'un arbre Ă l'autre ou entre les secteurs d'un mĂȘme arbre. Les taux trĂšs Ă©levĂ©s d'allofĂ©condation chez cette espĂšce autocompatible pourraient s'expliquer par certaines caractĂ©ristiques de sa biologie florale. La comparaison des estimations uni- et multilocus du taux d'allofĂ©condation montre un niveau nul ou trĂšs faible de consanguinitĂ©. Une analyse de variance Ă 2 facteurs montre qu'il n'y a pas de variation de frĂ©quence allopollinique d'un secteur Ă l'autre de la couronne d'un arbre : les secteurs d'un mĂȘme arbre ont donc pu ĂȘtre considĂ©rĂ©s comme des rĂ©pĂ©titions alĂ©atoires. En revanche, le nuage allopollinique est hĂ©tĂ©rogĂšne : i) d'un arbre Ă l'autre et les frĂ©quences allĂ©liques du pollen peuvent ĂȘtre diffĂ©rentes mĂȘme entre individus voisins (IDH1, tableau III), ii) entre les peuplements (GOT1 et MDH1). Dans la forĂȘt d'Issaux cette hĂ©tĂ©rogĂ©nĂ©itĂ© est maximale pour les arbres isolĂ©s (tableau V). Ă l'Aigoual, il n'y a pas d'hĂ©tĂ©rogĂ©nĂ©itĂ© interpeuplements mais une forte hĂ©tĂ©rogĂ©nĂ©itĂ© Ă l'intĂ©rieur de 2 des peuplements (tableau VI). Ces phĂ©nomĂšnes peuvent s'expliquer par la variabilitĂ© du nuage pollinique dans le temps en raison de dĂ©calages Ă dĂ©terminisme gĂ©nĂ©tique de la pĂ©riode de floraison (jusqu'Ă 20 j) et de la reproduction entre arbres synchrones d'un point de vue phĂ©nologique. Ce modĂšle pourrait expliquer, en particulier, l'hĂ©tĂ©rogĂ©nĂ©itĂ© de l'allopollen entre arbres voisins non synchrones. Cependant, il devrait conduire, au cours du temps, Ă une structuration des populations en groupes d'arbres prĂ©coces et d'arbres tardifs, ce qui n'a pas Ă©tĂ© observĂ©. En fait, il existe entre les individus les plus prĂ©coces et les plus tardifs toutes les classes intermĂ©diaires : la distribution des arbres en fonction de leur pĂ©riode de floraison est Ă peu prĂšs normale, ce qui induit des classes chevauchantes d'individus
Genetic structure of natural stands of Fagus sylvatica L. (beech)
International audienceThe spatial genetic structures of three French natural beech stands were analysed using poly-morphic enzyme loci. Two methods were used: F-statistics and spatial autocorrelation statistics. Within these stands where self-fertilization rate is 0, a low heterozygote deficit was observed which may be due to a moderate level of mating between relatives. However, no increase of this deficit was observed from one generation to the next. The spatial genetic structuring was low. Within one open stand composed of several patches, founder events are invoked to explain a significant autocorrela-tion. Within the two other stands, both dense, results are similar to those produced by simulations of an isolation by distance model. The genetic structure seems not to be stable in space and time which may be due to (i) a limited number of generations; (ii) an effective gene flow less limited than hypothesized; and (iii) fertility differences or phenological incompatibilities between individuals
Fixation nette de carbone dans la biomasse d'un peuplement de Pin maritime, dans les Landes de Gascogne
National audienc
Fixation nette de carbone dans la biomasse d'un peuplement de Pin maritime, dans les Landes de Gascogne
National audienc
When capacitive transduction meets the thermomechanical limit: Towards femto-newton force sensors at very high frequency
International audienceWe show that the capacitive transduction of a MEMS device using a setup based on a microwave detection scheme achieves the measurement of the thermomechanical noise spectrum of a high-frequency (>10 MHz) high-stiffness (>10 5 N/m) resonator, reaching the outstanding displacement resolution of 1 fm/âHz. This result paves the way for vibrating sensors with exquisite force resolution in the fN/vHz range, enabling large-bandwidth measurements of mechanical interactions at small scale and rheology of fluids at very high frequency. An example of application is given and concerns atomic force microscopy images of biomolecular assemblies
Endovascular management of ureteroarterial fistula. Single institution experience and systematic literature review
Background: Ureteroarterial fistula (UAF) represents an uncommon complication after urological surgery; however, this is a well-documented condition in patients with predisposing risk factors. The aim of the present study is to report and analyze the endovascular management of a series of patients with UAF, treated in authorsâ hospital, and to report and analyze the same data concerning patients retrieved from a systematic literature review. Methods: Authors conducted a retrospective analysis of prospectively collected data and a systematic literature review. The research was carried out through PubMed database searching the following keywords: âuretero arterial fistulaâ and âuretero iliac fistula.â It includes only articles reporting the endovascular management. Results: Forty-six articles were included in the present study for a total of 94 patients. Risk factors were as follows: chronic indwelling ureteral stents, pelvic surgery, radiotherapy, iliac artery pseudo-aneurysm, and chemotherapy. All patients had gross hematuria at presentation. Stent graft placement was performed in 89 patients, embolization in 5 patients, and iliac internal artery embolization combined with stent graft placement was performed in 24 patients. Four postprocedural complications were observed (4.2%). During a median follow-up of 8 months, 10 complications related to UAF were observed (10.6%): rebleeding (7 cases) and stent thrombosis (3 cases). Two patients died for causes related to UAF (2.1%): rebleeding (1) and retroperitoneal abscess (1). Conclusion: Based on the present data, endovascular treatment is feasible and safe with low postprocedural complications and mortality rate. Considering the increase in surgery and radiotherapy performed, UAF should be always debated in patients with massive hematuria
Demographic Genetic Analyses of the American Beech (Fagus grandifolra Ehrh.). Genetic Variations of Seed Populations in Maryland
Endovascular Management of Ureteroarterial Fistula: Single Institution Experience and Systematic Literature Review
Range wide versus local patterns of genetic diversity in hornbeam (Carpinus betulus L.)
A study based on AFLP markers was conducted to characterise the present population genetic structure of Carpinus betulus in Europe and to formulate guidelines for the use of this species in plantations on a local scale in Flanders. High within-population diversity and little (but significant) genetic differentiation were detected at both Flemish and European scales. However, there was a pattern of isolation by distance only at the European scale. Within-population gene diversity, a new rarefaction-based measure of number of genotypes (lsquoband richnessrsquo) and percentage of polymorphic loci are lower north of major mountain chains, suggesting that the mountain ranges formed a second bottleneck for the hornbeam during postglacial recolonisation. In Flanders, despite lower gene diversity, there were more polymorphic loci than in other European populations, a pattern that might have been caused by the mixing of material through planting, e.g. in hedges. In view of these findings, it is advised to create a single Flemish seed zone and to use preferentially reproductive material from this seed zone for new plantations in Flander