Trait adaptation promotes species coexistence in diverse predator and prey communities

Species can adjust their traits in response to selection which may strongly influence species coexistence. Nevertheless, current theory mainly assumes distinct and time‐invariant trait values. We examined the combined effects of the range and the speed of trait adaptation on species coexistence using an innovative multispecies predator–prey model. It allows for temporal trait changes of all predator and prey species and thus simultaneous coadaptation within and among trophic levels. We show that very small or slow trait adaptation did not facilitate coexistence because the stabilizing niche differences were not sufficient to offset the fitness differences. In contrast, sufficiently large and fast trait adaptation jointly promoted stable or neutrally stable species coexistence. Continuous trait adjustments in response to selection enabled a temporally variable convergence and divergence of species traits; that is, species became temporally more similar (neutral theory) or dissimilar (niche theory) depending on the selection pressure, resulting over time in a balance between niche differences stabilizing coexistence and fitness differences promoting competitive exclusion. Furthermore, coadaptation allowed prey and predator species to cluster into different functional groups. This equalized the fitness of similar species while maintaining sufficient niche differences among functionally different species delaying or preventing competitive exclusion. In contrast to previous studies, the emergent feedback between biomass and trait dynamics enabled supersaturated coexistence for a broad range of potential trait adaptation and parameters. We conclude that accounting for trait adaptation may explain stable and supersaturated species coexistence for a broad range of environmental conditions in natural systems when the absence of such adaptive changes would preclude it. Small trait changes, coincident with those that may occur within many natural populations, greatly enlarged the number of coexisting species.     

Effects of clove oil,essential oil of Lippia alba and 2‐phe anaesthesia on juvenile meagre,Argyrosomus regius (Asso, 1801)

The objectives of this experiment were to (i) determine the efficacy of essential oils of clove (CO) and Lippia alba (EOLA) to induce deep anaesthesia in juvenile specimens (49.0 ± 6.2 g body mass, 16.6 ± 0.8 cm; n = 8 per treatment) of meagre (Argyrosomus regius); and (ii) study the feasibility of these substances, together with 2‐phenoxyethanol (2‐PHE), as potential sedatives [low concentration: (i) EOLA: 12 mg L^?1; (ii) CO: 1 mg L^?1; and (iii) 2‐PHE: 33 mg·L ^?1; n = 8 per treatment] for live fish transport of this species. All test were performed at a constant temperature (18°C). Thus, the main primary stress indicator (plasma cortisol) and secondary factors (plasma metabolites) were evaluated. In addition, growth hormone (GH) mRNA expression was also evaluated in the pituitary gland. The results indicated that EOLA is considered to be effective for deep anaesthesia when the concentration is close to 160 mg L^?1, while CO produces the same effect when lower concentrations are added (40–50 mg L^?1). Regarding sedative concentrations, a significant ~3‐fold increase in plasma cortisol levels was detected in the EOLA group when compared to control specimens. In addition, glucose levels were not reduced and significantly increased (~1.6‐fold) for 2‐PHE in relation to the control fish. None of the anaesthetics promoted a significant difference for GH expression with respect to the control group, but a significant ~2‐fold increase for 2‐PHE treatment with respect to the EOLA exposition was found in this gene expression. Results show that none of the anaesthetics analysed, at least in the ranges of concentrations used in this study (EOLA 12 mg L^?1, CO 1 mg L^?1, 2‐PHE 33 mg L^?1), are recommended for live fish transport, as shown by the absence of inhibition on the stress parameters assessed.     

Site fertility drives temporal turnover of vegetation at high latitudes

Experimental evidence shows that site fertility is a key modulator underlying plant community changes under climate change. Communities on fertile sites, with species having fast dynamics, have been found to react more strongly to climate change than communities on infertile sites with slow dynamics. However, it is still unclear whether this generally applies to high‐latitude plant communities in natural environments at broad spatial scales. We tested a hypothesis that vegetation of fertile sites experiences greater changes over several decades and thus would be more responsive under contemporary climate change compared to infertile sites that are expected to show more resistance. We resurveyed understorey communities (vascular plants, bryophytes, and lichens) of four infertile and four fertile forest sites along a latitudinal bioclimatic gradient. Sites had remained outside direct human disturbance. We analyzed the magnitude of temporal community turnover, changes in the abundances of plant morphological groups and strategy classes, and changes in species diversity. In agreement with our hypothesis, temporal turnover of communities was consistently greater on fertile sites compared to infertile sites. However, our results suggest that the larger turnover of fertile communities is not primarily related to the direct effects of climatic warming. Furthermore, community changes in both fertile and infertile sites showed remarkable variation in terms of shares of plant functional groups and strategy classes and measures of species diversity. This further emphasizes the essential role of baseline environmental conditions and nonclimatic drivers underlying vegetation changes. Our results show that site fertility is a key determinant of the overall rate of high‐latitude vegetation changes but the composition of plant communities in different ecological contexts is variously impacted by nonclimatic drivers over time.     

Two optimized combination assays to examine apoptosis pathways in clinical samples.

BACKGROUND: A consequence of a number of diseases is an alteration in apoptosis. Currently, there is no single assay that measures the main stages of apoptosis, requiring that multiple assays be performed. This hinders studies on clinical samples that have limited cell numbers. Our objective was to combine and optimize assays that target specific stages of apoptosis for use in a typical clinical blood sample. METHODS: Two flow cytometric assays were developed for use on peripheral blood mononuclear cells (PBMC) collected in two 8-ml tubes from a single draw. One measures caspase-12 activity, the level of active caspase-3 and DNA fragmentation. The second assesses depolarization of the mitochondria and phosphatidylserine externalization. Cell populations present within the samples were determined by flow cytometry. Apoptosis was validated by ELISA. RESULTS: Each assay was optimized for use with cell numbers and sample volumes typical of clinical blood samples. Each combination assay effectively distinguished apoptotic from nonapoptotic blood cells. CONCLUSIONS: This combined optimized method comprised of two independent assays makes it possible to assay the major pathways of apoptosis in addition to determining the blood cell subsets that are affected.     

Inhibition of Vancomycin-Resistant <Emphasis Type="Italic">Enterococcus</Emphasis> by Continuous-Flow Cultures of Human Stool Microflora With and Without Anaerobic Gas Supplementation

A continuous-flow competitive exclusion (CFCE) culture model of human stool microflora was used to examine whether supplemental anaerobic gas is necessary for maintenance of anaerobes and inhibition of vancomycin-resistant Enterococcus (VRE). CFCE cultures of human stool microflora were maintained with supplemental nitrogen, without supplemental nitrogen, or with percolated room air. Cultures with or without supplemental nitrogen maintained >9 log₁₀ CFU mL^–1 of obligate anaerobes and eliminated 10⁶ CFU mL^–1 of VRE. When room air was percolated into the culture, anaerobes were detected at 2 log₁₀ CFU mL^–1, and the same VRE inoculum was not eliminated (P < 0.001). These data demonstrate that human stool CFCE cultures maintain high levels of obligate anaerobes and inhibit VRE without the addition of supplemental anaerobic gas.     

Racial and ethnic variations in knowledge and attitudes about genetic testing

This study was designed to shed light on whether differences in utilization of genetic testing by African-Americans, Latinos, and non-Hispanic Whites are due primarily to different preferences, or whether they instead reflect other values and beliefs or differential access. It explores the values, attitudes, and beliefs of African-Americans, Latinos, and non-Hispanic Whites with respect to genetic testing by means of a telephone survey of representative samples of these three groups. The study finds clear evidence that Latinos and African-Americans are, if anything, more likely to express preferences for both prenatal and adult genetic testing than White respondents. At the same time, they hold other beliefs and attitudes that may conflict with, and override, these preferences in specific situations. African-Americans and Latinos are also less knowledgeable about genetic testing than non-Hispanic Whites, and they are less likely to have the financial resources or insurance coverage that would facilitate access to testing.     

Betaine improves growth, but does not induce whole body or hepatic palmitate oxidation in swine (Sus scrofa domestica)

Dietary betaine may reduce carcass fat in growing pigs. We explored the effects of betaine on short-term growth and in vivo and in vitro fatty acid oxidation. Pigs were housed in metabolism crates and fed diets containing either 0% (control), 0.125% or 0.5% betaine at 80% of ad libitum energy intake. Fatty acid oxidation was measured during intravenous infusions of 1-(13)C-palmitate and in hepatocytes incubated in the presence or absence of betaine and carnitine. CO2 and palmitate isotopic enrichments were determined by mass spectrometry. Pigs consuming 0.125% and 0.5% betaine for at least 9 days had growth rates that were 38% and 12% greater than controls, respectively. Feed efficiency was also improved with betaine. Fasting increased palmitate oxidation rates 7-8-fold (P < 0.01), but betaine had no effect in either the fed or fasted state (P > 0.1). For hepatocytes, carnitine but not betaine enhanced palmitate oxidation. This response suggests that previously observed reduction in adipose accretion must be via a mechanism other than oxidation. Betaine had no effect on plasma non-esterified fatty acids or urea nitrogen. Under the confinement conditions in this study, dietary betaine improved animal growth responses, but it had no apparent effect on either whole body or hepatic fatty acid oxidation.