1,721,211 research outputs found
Extinction risk and eco-evolutionary dynamics in a variable environment with increasing frequency of extreme events
Full text linkOne of the most dramatic consequences of climate change will be the intensification and increased frequency of extreme events. I used numerical simulations to understand and predict the consequences of directional trend (i.e. mean state) and increased variability of a climate variable (e.g. temperature), increased probability of occurrence of point extreme events (e.g. floods), selection pressure and effect size of mutations on a quantitative trait determining individual fitness, as well as the their effects on the population and genetic dynamics of a population of moderate size. The interaction among climate trend, variability and probability of point extremes had a minor effect on risk of extinction, time to extinction and distribution of the trait after accounting for their independent effects. The survival chances of a population strongly and linearly decreased with increasing strength of selection, as well as with increasing climate trend and variability. Mutation amplitude had no effects on extinction risk, time to extinction or genetic adaptation to the new climate. Climate trend and strength of selection largely determined the shift of the mean phenotype in the population. The extinction or persistence of the populations in an 'extinction window' of 10 years was well predicted by a simple model including mean population size and mean genetic variance over a 10-year time frame preceding the 'extinction window', although genetic variance had a smaller role than population size in predicting contemporary risk of extinction. © 2014 The Author(s) Published by the Royal Society
Review of: A Computational Approach to Statistical Arguments in Ecology and Evolution by George F. Estabrook
No full textFood abundance, kittiwake life histories, and colony dynamics in the Northeastern Pacific:implications of climate change and regime shifts
No full textBlack-legged kittiwakes Rissa tridactyla in the Northeastern Pacific will increasingly experience climate-induced changes in the variability of forage fish, which will influence both the quantity and quality of food and may thus alter the population dynamics of kittiwake colonies. However, the relative roles of individual- and population-level traits in determining colony dynamics and risk of extinction are still unclear. We combined models of components of the Pacific kittiwake life history with empirical data linking physiological stress and food abundance to provide a unified treatment of kittiwake colony dynamics. We simulated the dynamics of colonies with high, medium and low responsiveness of productivity to variation in nutritional stress in breeding birds, using data from Alaskan colonies. We found that the risk of quasi-extinction strongly decreased with a moderate increase in the potential number of yearly immigrants. Pre-breeding mortality as a function of growth during development had only a marginal role in determining median number of breeding pairs over simulation time. We predict that temporal auto - correlation of colony-wide average productivity and high nutritional stress, particularly if consistent over time, will increase quasi-extinction risk. Our work shows that colonies with low productivity have little chance of persistence even when survival of pre-breeding and breeding birds is high, and that the nature of the temporal auto-correlation of food conditions and productivity is crucial to understand the effect of environmental fluctuations, regime shifts, and climate change on population dynamics of kittiwakes. We use the model to highlight the most valuable future empirical studies
Linking food availability, body growth and survival in the Black-legged Kittiwake Rissa tridactyla
No full textAnomalous electrophoretic behavior of a chitinase isoform from grape berries and wine in glycol chitin-containing SDS-PAGE gels
No full textEvolution of serotiny in maritime pine (Pinus pinaster) in the light of increasing frequency of fires
No full textWildfire frequency and intensity in the Mediterranean region are predicted to increase with climate and anthropogenic changes in the following decades. Pines species often posses fire-embracing and fire-avoiding strategies that increase the probability of persistence and performance in fire-prone habitats. One such strategy is serotiny, i.e., the capacity to retain seeds in long-closed cones within the plant canopy; serotinous cones release seeds only when either a fire or a heat shock occurs. In this work, we used a simulation approach and Pinus pinaster populations as a model system to investigate how (i) an increased frequency of fire, (ii) genetic characteristics of serotiny, and (iii) observed differences in life histories interact to determine (a) risk of local population extinction and (b) temporal changes in the prevalence of serotiny in the modeled population. In addition, we tested whether the contemporary evolution of serotiny in the face of increased probability of occurrence of fires increased the probability of population persistence with respect to a scenario in which serotiny was not allowed to evolve. Our simulations showed that over the 300 years of simulated time, the evolution of serotiny did not substantially contribute to the persistence of populations. Extinction risk increased with the increasing probability of occurrence of fire and slightly decreased with (i) higher gene flow from outside the modeled population, and (ii) higher prevalence of serotiny at the beginning of the simulation. The prevalence of serotiny at the end of simulation time was difficult to predict and mostly driven by stochasticity. © 2014 Springer Science+Business Media Dordrecht
Estratti da vinaccioli, metodo di preparazione e uso degli stessi per il trattamento di vini
No full textE' riportato un processo di estrazione di un preparato proteico da vinaccioli e una applicazione di tale estratto per la chiarifica dei vin
UTILIZZO DEL CHITOSANO ANIMALE NELLA CHIARIFICA DEI VINI E DEI MOSTI
Full text linkPROVE DI CHIARIFICA SU SCALA DI LABORATORIO DI MOSTO E DUE VINI BIANCHI E ROSSI. CONFRONTO DEL CHITOSANO ANIMALE CON ALCUNI PRODOTTI REPERIBILI IN COMMERCI
Removal of specific protein components by chitin enhances protein stability in a white wine
No full textThe effect of chitin [poly(N-acetyl-1,4-ß-D-glucopyranosamine)], an abundant, low-cost natural polymer,
on white wine stabilization on a laboratory scale was studied in comparison with bentonite fining. Treatments
of an unfined wine with increasing doses of chitin allowed a reduction of up to 80% of the haze induced by the
heat test, which corresponded to a reduction in wine protein content of less than 29%. In contrast, bentonite fining,
although allowing a complete stabilization, resulted in the removal of almost all the proteins from wine. These
results suggest that chitin can remove from wine protein components involved in haze formation more specifically
than bentonite. SDS-PAGE analysis of both the proteins remaining in wine and those adsorbed by chitin confirmed
this specificity. Chitinolytic activity detection after SDS-PAGE separation demonstrated that a main protein component
removed by chitin corresponded to the class IV chitinase of grape origin involved in white wine instability. Because
class IV chitinases are characterized by bearing a chitin-binding domain, a specific interaction of these wine
proteins with chitin can be suggested. Preliminary trials with chitin immobilized in a column system indicated the
possibility to regenerate this matrix and to use it continuously for white wine stabilization. However, the effects
on both the organoleptic quality and the long-term stability of white wines treated with chitin need to be determined
in the actual winemaking conditions
Changes in total and individual proteins from grape to wine: effects on the heat test stability
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