No description available.

Red oak (Quercus spp.) acorns provide food for wildlife and are propagules for regeneration of these trees. Annual yield of acorns varies temporally and site-specifically. I examined acorn yield in relation to hydrology and soils of hardwood bottomlands at five sites in the Mississippi Alluvial Valley and a site in the Mississippi Interior Flatwoods Region during fall-winter 2012-2013. Acorn yield varied among sites (mean = 44.9 acorns/m2; SE = 6.7; CV = 14.9%). Duration of flooding during the growing season differed among sites which influenced soil characteristics. Acorn yield varied inversely with number of days sites were inundated during the growing season (R2 = 0.6725; P = 0.0456; n = 6) during 2012-2013. Managers should consider alleviating growing season flooding of red oaks, which may increase acorn yield and sustain red oaks and other bottomland hardwoods.

No description available.

The purpose of this study was to determine how two morphs of the acorn barnacle, Chthamalus anisopoma, coexist on rocky intertidal shores in the northern Gulf of California. The test of one of these forms (here called "typical") has the conical, volcano shape which is characteristic of acorn barnacles while the test of the atypical form (here called "bent") grows bent-over so that the plane of the aperture's rim is perpendicular to the substrate. I tested the hypotheses that bents are more resistant than typicals to: (1) desiccation during low tides and (2) attack by a carnivorous snail (Acanthina angelica) involving the use of a labial spine. These two hypotheses (which were suggested from analysis of the distribution patterns of the two morphs) were tested in conjunction with experiments designed to determine whether the bent form is genetically controlled or environmentally induced. The results indicated that the bent-over morph is a developmental response to the presence of A. angelica and that it is more resistant than the typical form to specialized predation by this gastropod. I also tested the hypotheses that: (1) bents are inferior competitors for primary rock space, and (2) the bent-over morphology places constraints on growth and reproduction. I found no evidence to suggest that bents are inferior competitors for space. They were, however, found to grow more slowly than typicals and to brood fewer eggs per unit body size. In summary, the bent-over form of C. anisopoma is a conditional response to the presence of a predator and both the conditional strategy and the dimorphism appear to be maintained by a trade-off between resistance to predation and the ability to convert resources into offspring.

Acorns of red oaks (Quercus spp; Subgenus Erythrobalanus) are important forage for wildlife and seed for oak regeneration. I estimated production of viable acorns by red oaks in 5 forests in the Mississippi Alluvial Valley (MAV) and 2 greentree reservoirs (GTRs) in Mississippi. Mean acorn production in the MAV was 439 kg(dry)/ha of red oak crown (CV = 29%) during autumn-winter 2009-2010 and 794 kg/ha (CV = 19%) in GTRs during autumn-winters 2008-2010. I recommend researchers sample acorn production in the MAV for ≥5 years to improve precision of estimates (i.e., CV ≤ 15%). I estimated mass and gross energy (GE) of viable red oak acorns after 90 days in unflooded and flooded hardwood bottomlands in Mississippi. Within species, mass loss of acorns was <8.4% and variation in GE ≤0.08 kcal(dry)/g. Winter decomposition of intact viable red oak acorns would have minimal effect on wildlife carrying capacity of hardwood bottomlands.

No description available.

This study was designed for the investigation of antioxidative, and antimicrobial properties of Quercus brantii L. (Q.brantii.) seed extract. Phenolic profile of the total extract was determined by using High Performance Liquid Chromatography (HPLC) and confirmed by High Resolution Mass Spectroscopy (HRMS). Solvent fractionation was performed to seperate bioactive compounds in total extract by using solubility differences. In comparison of fractions, ethyl acetate and diethyl ether phases have revealed highest antioxidant effect. Due to the low yield and high number of the molecules in ethyl acetate fraction, HRMS was used to characterize the compounds. On the other hand, in diethyl ether fraction, there was a single major compound which showed high antioxidant activity. The major compound, was purified by column chromatography and characterized by NMR, IR and HRMS as methyl gallate. E.coli, P.mirabilis, S.aureus, S.pyogenes bacterial strains were used to determine the antimicrobial activity of Q. brantii seed crude extract, fractions and isolated compound by disc diffusion, MIC and MBC methods. Isolated methyl gallate and ethyl acetate fraction displayed a significant effect on all bacterial strains as high as reference antibiotics. Consequently, crude Q. branti extract, isolated methyl gallate and ethyl acetate fraction could be considered as powerful antimicrobial agents, and at the same time efficacious antioxidants.

The intertidal zone is characterized by persistent, tidally-driven fluctuations in both abiotic (e.g., temperature, [O2], salinity) and biotic (e.g., food availability, predation) conditions, which makes this a very physiologically challenging habitat for resident organisms. The magnitude and degree of variability of these environmental stressors differs between intertidal zones, with the most extreme physiological stress often being experienced by organisms in the high intertidal. Given that many of the fluctuating conditions in this environment are primary drivers of metabolic rate (e.g., temperature, [O2], food availability), we hypothesized that sessile conspecifics residing in different tidal zones would exhibit distinct ‘metabolic phenotypes,’ a term we use to collectively describe the organisms’ baseline metabolic performance and capacity. To investigate this hypothesis, we collected acorn barnacles (Balanus glandula) from low, mid, and high intertidal positions in San Luis Obispo Bay, CA and measured a suite of biochemical (whole-animal citrate synthase (CS) and lactate dehydrogenase (LDH) activity, aerial [lactate]), physiological (O2 consumption rates), morphological (body size), and behavioral (e.g., cirri beat frequency, % time operculum open) indices of metabolism. We found tidal zone-dependent differences in B. glandula metabolism that primarily related to anaerobic capacity, feeding behaviors and body size. Barnacles from the low intertidal tended to have a greater capacity for anaerobic metabolism (i.e., increased LDH activity), feed less when submerged, and be smaller in size compared to conspecifics in the high intertidal. We did not, however, see differences between barnacles from different tidal heights in whole-animal [lactate] following 24h of air exposure, which indicates that the enhanced capacity of low intertidal barnacles for anaerobic metabolism may have evolved to support metabolism during more prolonged episodes of emersion (>>24h) or during events other than emersion (e.g., coastal hypoxia, predation). There were also no significant differences in CS activity or baseline oxygen consumption rates (in air or seawater at 14˚C) across tidal heights, which implies that aerobic metabolic capacity may not be as sensitive to tidal position as anaerobic processes. Understanding how individuals occupying different shore heights differ in their metabolic capacity becomes increasingly interesting in the context of global climate change, given that the intertidal zone is predicted to experience even greater extremes in abiotic stress.

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Le chêne rouge d’Amérique (Quercus rubra L.) est un arbre originaire d’Amérique du Nord et introduit en Europe à partir de la fin du XVIIème siècle pour l’ornementation et le commerce du bois. Le but de cette thèse est de comprendre les mécanismes écologiques et évolutifs qui contribuent à la dynamique et au succès de l’introduction de Q. rubra en Europe. Nous avons montré que cette espèce naturalisée et plantée dans certains pays européens parvient aisément à se développer de façon naturelle dans les forêts de feuillus et de conifères. La dispersion de ses glands est notamment rendue possible par des animaux fouisseurs-disperseurs, tels que les écureuils et les mulots, qui cependant préfèrent les glands du chêne natif Q. robur. Lors de l’introduction d’une espèce dans un nouvel environnement, des processus évolutifs sont susceptibles de se produire et d’engendrer des modifications phénotypiques et génétiques au sein des populations introduites. Une analyse comparative de la structure et de la diversité génétique des populations natives et introduites de Q. rubra a démontré que seulement deux des trois groupes génétiques de l’aire américaine sont actuellement présents en Europe. Aucun goulot d’étranglement fort n’a été détecté lors de l’introduction des populations en Europe laissant supposer que des introductions multiples ont pu maintenir la diversité génétique dans les populations introduites. Une analyse comparative des traits phénotypiques a permis de montrer que les populations introduites de Q. rubra présentent une croissance supérieure par rapport aux populations natives. Une différenciation génétique au sein des populations introduites est en cours pour le trait de débourrement foliaire suggérant une possible évolution adaptative rapide depuis l’introduction. / Northern Red Oak (Quercus rubra L.) is a tree native to North America and introduced in Europe at the end of the 17th century as an ornamental and forestry species. The aim of this dissertation is to understand the ecological and evolutionary mechanisms contributing to its dynamics and success in Europe. We demonstrated that this species naturalized and planted insome European countries can easily naturally grow in deciduous and conifer forests. Acorn dispersal away from mother-trees was made possible by scatter-hoarding animals such as squirrels and mice that take away acorns, although the animals still preferred acorns of the native oak Q. robur. During species introduction in a new environment, evolutionary processes can occurand lead to phenotypic and genetic changes. A comparative analysis of the genetic structure and diversity of Q. rubra populations from the native and introduced ranges demonstrated that onlytwo of the three genetic clusters encountered in North America are currently present in Europe.No strong bottleneck event was detected during the introduction of Q. rubra populations in Europe suggesting that multiple introductions could have maintained genetic diversity in introduced populations. A comparative analysis of phenotypic traits showed that introduced populations of Q.rubra present a higher growth compared to that of native populations. A genetic differentiation within European populations is on going regarding phenology of leaf budburst suggesting apossible rapid adaptive evolution since introduction.