Facilitative and competitive effects of a large species with defensive traits on a grazing-adapted, small species in a long-term deer grazing habitat

Plants can adapt to grazing environments by developing defensive traits, such as spines and toxins, or having a small phenotype, such as short and prostrate growth forms. This study examined facilitative and competitive interactions between species with different types of grazing adaptation. We predicted that large species with defensive traits sometimes protect grazing-adapted species without defensive traits from herbivores, but competitively suppress them overall. We conducted an experiment using fences and removals of an unpalatable plant in the long-term deer grazing habitat of Nara Park in Nara, Japan. We evaluated the seasonal variations in the facilitative and competitive effects of a defensive perennial, Urtica thunbergiana, on the growth, survival, reproduction, and final fitness of a small palatable annual species, Persicaria longiseta, during a growing season. The populations of the two species in the park have adapted to the grazed habitat by increasing the density of stinging hairs (Urtica) and developing inherently short shoots and small leaves (Persicaria). We found that Urtica individuals had facilitative effects on the growth of Persicaria individuals under grazing during a few periods of the growing season, but had neutral effects on survival and plant fitness throughout the season. In the fenced plots, Urtica had negative effects on the growth, survival, and reproduction of Persicaria. These results suggest that the relative importance of the facilitative and competitive effects of Urtica on Persicaria fluctuated due to seasonal variations in grazing pressure and vegetative productivity. Although well-defended plants often facilitate less-defended species, we conclude that the facilitative effects of Urtica on Persicaria are limited in a plant community with a long history of intensive grazing

Grand Unification of Flavor Mixings

An origin of flavor mixings in quark and lepton sectors is still a mystery, and a structure of the flavor mixings in lepton sector seems completely different from that of quark sector. In this letter, we point out that the flavor mixing angles in quark and lepton sectors could be unified at a high energy scale, when neutrinos are degenerate. It means that a minimal flavor violation at a high energy scale can induce a rich variety of flavor mixings in quark and lepton sectors at a low energy scale through quantum corrections.Comment: 5 pages, 12 figures, references added, version to appear in EP

Relationships between survival and habitat suitability of semi- aquatic mammals

Spatial distribution and habitat selection are integral to the study of animal ecology. Habitat selection may optimize the fitness of individuals. Hutchinsonian niche theory posits the fundamental niche of species would support the persistence or growth of populations. Although niche-based species distribution models (SDMs) and habitat suitability models (HSMs) such as maximum entropy (Maxent) have demonstrated fair to excellent predictive power, few studies have linked the prediction of HSMs to demographic rates. We aimed to test the prediction of Hutchinsonian niche theory that habitat suitability (i.e., likelihood of occurrence) would be positively related to survival of American beaver (Castor canadensis), a North American semi-aquatic, herbivorous, habitat generalist. We also tested the prediction of ideal free distribution that animal fitness, or its surrogate, is independent of habitat suitability at the equilibrium. We estimated beaver monthly survival probability using the Barker model and radio telemetry data collected in northern Alabama, United States from January 2011 to April 2012. A habitat suitability map was generated with Maxent for the entire study site using landscape variables derived from the 2011 National Land Cover Database (30-m resolution). We found an inverse relationship between habitat suitability index and beaver survival, contradicting the predictions of niche theory and ideal free distribution. Furthermore, four landscape variables selected by American beaver did not predict survival. The beaver population on our study site has been established for 20 or more years and, subsequently, may be approaching or have reached the carrying capacity. Maxent-predicted increases in habitat use and subsequent intraspecific competition may have reduced beaver survival. Habitat suitability-fitness relationships may be complex and, in part, contingent upon local animal abundance. Future studies of mechanistic SDMs incorporating local abundance and demographic rates are needed

Variation of almond yield, biometry, α-tocopherol levels, and antioxidant properties with nitrogen fertilization

A two years’ experiment (2015–2016) was set in a factorial design in which the effect of two application forms of nitrogen (N) (soil and soil + foliar spray) in different doses (0, 25, 50, and 100 kg N ha-1) on almond (Prunus dulcis Mill. cv. “Masbovera”) was evaluated. Kernel yield, biometric properties, phytochemicals, and antioxidant activities were assessed. The results showed that almond kernel yield increases with an increment in N rate doses and was positively correlated with kernel weight and thickness, and negatively with fruit weight. The levels of α-tocopherol and total polyphenol content were higher with lower N doses (25 and 50 kg N ha–1). The antioxidant activities were positively correlated with polyphenol content. Based on our results, excessive N rates over 50 kg/ha depreciate the levels of α-tocopherol, total polyphenols, and antioxidant bioactivities of kernels. Practical applications Almond is an important nut (dry) fruit that contains high levels of α-tocopherol, moderate levels of polyphenols, and high antioxidant activities, all responsible for their claimed health-promoting properties. Almond trees are known by their alternate behavior in which kernel yield and levels of phytochemicals and other compounds are highly variable between years. This article studies the usage of a sustainable nitrogen fertilization program toward a reduction of their alternate behavior, preserving and promoting their antioxidant properties and their levels of phytochemicals, particularly α-tocopherol and polyphenols. Our findings may provide a useful guide for adequate nitrogen fertilization program toward a better almond kernel qualityinfo:eu-repo/semantics/publishedVersio

Direct and indirect effects of a pH gradient bring insights into the mechanisms driving prokaryotic community structures

Background: pH is frequently reported as the main driver for prokaryotic community structure in soils. However, pH changes are also linked to "spillover effects" on other chemical parameters (e.g., availability of Al, Fe, Mn, Zn, and Cu) and plant growth, but these indirect effects on the microbial communities are rarely investigated. Usually, pH also co-varies with some confounding factors, such as land use, soil management (e.g., tillage and chemical inputs), plant cover, and/or edapho-climatic conditions. So, a more comprehensive analysis of the direct and indirect effects of pH brings a better understanding of the mechanisms driving prokaryotic (archaeal and bacterial) community structures. Results: We evaluated an agricultural soil pH gradient (from 4 to 6, the typical range for tropical farms), in a liming gradient with confounding factors minimized, investigating relationships between prokaryotic communities (16S rRNA) and physical-chemical parameters (indirect effects). Correlations, hierarchical modeling of species communities (HMSC), and random forest (RF) modeling indicated that both direct and indirect effects of the pH gradient affected the prokaryotic communities. Some OTUs were more affected by the pH changes (e.g., some Actinobacteria), while others were more affected by the indirect pH effects (e.g., some Proteobacteria). HMSC detected a phylogenetic signal related to the effects. Both HMSC and RF indicated that the main indirect effect was the pH changes on the availability of some elements (e.g., Al, Fe, and Cu), and secondarily, effects on plant growth and nutrient cycling also affected the OTUs. Additionally, we found that some of the OTUs that responded to pH also correlated with CO2, CH4, and N2O greenhouse gas fluxes. Conclusions: Our results indicate that there are two distinct pH-related mechanisms driving prokaryotic community structures, the direct effect and "spillover effects" of pH (indirect effects). Moreover, the indirect effects are highly relevant for some OTUs and consequently for the community structure; therefore, it is a mechanism that should be further investigated in microbial ecology.Peer reviewe

Direct and indirect effects of a pH gradient bring insights into the mechanisms driving prokaryotic community structures

Background: pH is frequently reported as the main driver for prokaryotic community structure in soils. However, pH changes are also linked to "spillover effects" on other chemical parameters (e.g., availability of Al, Fe, Mn, Zn, and Cu) and plant growth, but these indirect effects on the microbial communities are rarely investigated. Usually, pH also co-varies with some confounding factors, such as land use, soil management (e.g., tillage and chemical inputs), plant cover, and/or edapho-climatic conditions. So, a more comprehensive analysis of the direct and indirect effects of pH brings a better understanding of the mechanisms driving prokaryotic (archaeal and bacterial) community structures. Results: We evaluated an agricultural soil pH gradient (from 4 to 6, the typical range for tropical farms), in a liming gradient with confounding factors minimized, investigating relationships between prokaryotic communities (16S rRNA) and physical-chemical parameters (indirect effects). Correlations, hierarchical modeling of species communities (HMSC), and random forest (RF) modeling indicated that both direct and indirect effects of the pH gradient affected the prokaryotic communities. Some OTUs were more affected by the pH changes (e.g., some Actinobacteria), while others were more affected by the indirect pH effects (e.g., some Proteobacteria). HMSC detected a phylogenetic signal related to the effects. Both HMSC and RF indicated that the main indirect effect was the pH changes on the availability of some elements (e.g., Al, Fe, and Cu), and secondarily, effects on plant growth and nutrient cycling also affected the OTUs. Additionally, we found that some of the OTUs that responded to pH also correlated with CO2, CH4, and N2O greenhouse gas fluxes. Conclusions: Our results indicate that there are two distinct pH-related mechanisms driving prokaryotic community structures, the direct effect and "spillover effects" of pH (indirect effects). Moreover, the indirect effects are highly relevant for some OTUs and consequently for the community structure; therefore, it is a mechanism that should be further investigated in microbial ecology.Peer reviewe

Complex orbital state in manganites

The $e_g$-orbital states with complex coefficients of the linear combination of $x^2-y^2$ and $3z^2-r^2$ are studied for the ferromagnetic state in doped manganites. Especially the focus is put on the competition among uniform complex, staggered complex, and real orbital states. As the hole-doping $x$ increases, the real, the canted complex, and the staggered complex orbital states appears successively. Uniform complex state analoguous to Nagaoka ferromagnet does not appear. These complex states can be expressed as a resonating state among the planer orbitals as the orbital liquid, accompanied by no Jahn-Teller distortion.Comment: 14 pages, 6 figure

The Orbital Order Parameter in La0.95Sr0.05MnO3 probed by Electron Spin Resonance

The temperature dependence of the electron-spin resonance linewidth in La0.95Sr0.05MnO3 has been determined and analyzed in the paramagnetic regime across the orbital ordering transition. From the temperature dependence and the anisotropy of linewidth and $g$-value the orbital order can be unambiguously determined via the mixing angle of the wave functions of the $e_{\rm g}$-doublet. The linewidth shows a similar evolution with temperature as resonant x-ray scattering results