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YAN‐SHIH LIN AIMEE BOURNE BELINDA E. MEDLYN DAVID S. ELLSWORTH 《Plant, cell & environment》2013,36(2):262-274
Models of stomatal conductance (gs) are based on coupling between gs and CO2 assimilation (Anet), and it is often assumed that the slope of this relationship (‘g1’) is constant across species. However, if different plant species have adapted to different access costs of water, then there will be differences in g1 among species. We hypothesized that g1 should vary among species adapted to different climates, and tested the theory and its linkage to plant hydraulics using four Eucalyptus species from different climatic origins in a common garden. Optimal stomatal theory predicts that species from sub‐humid zones have a lower marginal water cost of C gain, hence lower g1 than humid‐zone species. In agreement with the theory that g1 is related to tissue carbon costs for water supply, we found a relationship between wood density and g1 across Eucalyptus species of contrasting climatic origins. There were significant reductions in the parameter g1 during drought in humid but not sub‐humid species, with the latter group maintaining g1 in drought. There are strong differences in stomatal behaviour among related tree species in agreement with optimal stomatal theory, and these differences are consistent with the economics involved in water uptake and transport for carbon gain. 相似文献
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R. BRIAN LANGERHANS CRAIG A. LAYMAN AIMEE K. LANGERHANS THOMAS J. DEWITT 《Biological journal of the Linnean Society. Linnean Society of London》2003,80(4):689-698
We examined intraspecific morphological diversification between river channel and lagoon habitats for two Neotropical fish ( Bryconops caudomaculatus , Characidae; Biotodoma wavrini , Cichlidae). We hypothesized that differences between habitats (e.g. flow regime, foraging opportunities) might create selective pressures resulting in morphological divergence between conspecific populations. We collected fish from four channel-lagoon habitat pairs in the Río Cinaruco, Venezuela, and compared body morphology using geometric morphometrics. There were two aspects of divergence in both species: (1) placement of maximum body depth and (2) orientation of the mouth. For both species, maximum body depth was positioned more anteriorly (i.e. fusiform) in the river channel than in lagoons. Both species exhibited a relatively terminal mouth in lagoons compared to the channel. The mouth of B. caudomaculatus was relatively upturned, whereas the mouth of B. wavrini was relatively subterminal, in channel habitats. Observed morphological patterns are consistent with functional morphological principles suggesting adaptive divergence. We also show that spatial distance between habitats, presumably reflecting rates of population mixing, appears to have constrained diversification. For both species, morphological divergence increased with distance between habitats. Thus morphological divergence between channel and lagoon habitats apparently reflects a balance between diversification driven by natural selection, and homogenization driven by population mixing. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 689–698. 相似文献
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ELIE G. KARAM JOHN FAYYAD AIMEE NASSER KARAM CAROLINE CORDAHI TABET NADINE MELHEM ZEINA MNEIMNEH HANI DIMASSI 《World psychiatry》2008,7(2):103-109
The purpose of this study was to examine the effectiveness and specificity of a classroom-based psychosocial intervention after war. All students (n=2500) of six villages in Southern Lebanon designated as most heavily exposed to war received a classroom-based intervention delivered by teachers, consisting of cognitive-behavioural and stress inoculation training strategies. A random sample of treated students (n=101) and a matched control group (n=93) were assessed one month post-war and one year later. Mental disorders and psychosocial stressors were assessed using the Diagnostic Interview for Children and Adolescents - Revised with children and parents. War exposure was measured using the War Events Questionnaire. The prevalence of major depressive disorder (MDD), separation anxiety disorder (SAD) and post-traumatic stress disorder (PTSD) was examined pre-war, one month post-war (pre-intervention), and one year post-war. Specificity of treatment was determined by rating teachers’ therapy diaries. The rates of disorders peaked one month post-war and decreased over one year. There was no significant effect of the intervention on the rates of MDD, SAD or PTSD. Post-war MDD, SAD and PTSD were associated with pre-war SAD and PTSD, family violence parameters, financial problems and witnessing war events. These findings have significant policy and public health implications, given current practices of delivering universal interventions immediately post-war. 相似文献
4.
We isolated and characterized 12 microsatellite loci for the North American medicinal leech, Macrobdella decora. Macrobdella decora is abundant in central and northern North American freshwater systems. The resulting microsatellite library, the first for any species of leech or any clitellate annelid, demonstrates the efficacy of this type of analysis on unexploited leech populations and should serve as a baseline for comparison with other species, notably the commercially important and threatened European medicinal leech, Hirudo medicinalis. 相似文献
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The role of anxious and hyperthymic temperaments in mental disorders: a national epidemiologic study
ELIE G. KARAM MARIANA M. SALAMOUN JOUMANA S. YERETZIAN ZEINA N. MNEIMNEH AIMEE N. KARAM JOHN FAYYAD ELIE HANTOUCHE KAREEN AKISKAL HAGOP S. AKISKAL 《World psychiatry》2010,9(2):103-110
Temperament has been demonstrated clinically to be linked to mental disorders.
We aimed to determine the possible role of temperament in mental disorders
in a national epidemiologic study. A nationally representative sample of adults
(n=1320) was administered the Lebanese-Arabic version of the Temperament Evaluation
of the Memphis, Pisa, Paris and San Diego Autoquestionnaire (TEMPS-A), and
the Arabic CIDI 3.0, as part of the LEBANON study. The association among temperaments
and DSM-IV mood, anxiety, and impulse control disorders was assessed. The
anxious temperament was shown to be a robust predictor of most disorders,
especially within the anxiety and depressive clusters. The hyperthymic temperament
had a uniquely protective effect on most mental disorders, with the exception
of separation anxiety, bipolar, substance abuse and impulse control disorders.
These effects were moderated by age and education. Temperaments, previously
largely neglected in epidemiologic studies, could play a major role in the
origin of mental disorders. 相似文献
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PAUL KARDOL COURTNEY E. CAMPANY LARA SOUZA RICHARD J. NORBY JAKE F. WELTZIN AIMEE T. CLASSEN 《Global Change Biology》2010,16(10):2676-2687
Atmospheric and climatic change can alter plant biomass production and plant community composition. However, we know little about how climate change‐induced alterations in biomass production affect plant species composition. To better understand how climate change will alter both individual plant species and community biomass, we manipulated atmospheric [CO2], air temperature, and precipitation in a constructed old‐field ecosystem. Specifically, we compared the responses of dominant and subdominant species to our climatic treatments, and explored how changes in plant dominance patterns alter community evenness over 2 years. Our study resulted in four major findings: (1) all treatments, elevated [CO2], warming, and increased precipitation increased plant community biomass and the effects were additive rather than interactive, (2) plant species differed in their response to the treatments, resulting in shifts in the proportional biomass of individual species, which altered the plant community composition; however, the plant community response was largely driven by the positive precipitation response of Lespedeza, the most dominant species in the community, (3) precipitation explained most of the variation in plant community composition among treatments, and (4) changes in precipitation caused a shift in the dominant species proportional biomass that resulted in lower community evenness in the wet relative to dry treatments. Interestingly, compositional and evenness responses of the subdominant community to the treatments did not always follow the responses of the whole plant community. Our data suggest that changes in plant dominance patterns and community evenness are an important part of community responses to climatic change, and generally, that such compositional shifts can alter ecosystem biomass production and nutrient inputs. 相似文献
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RONALD C KESSLER MATTHIAS ANGERMEYER JAMES C ANTHONY RON DE GRAAF KOEN DEMYTTENAERE ISABELLE GASQUET GIOVANNI DE GIROLAMO SEMYON GLUZMAN OYE GUREJE JOSEP MARIA HARO NORITO KAWAKAMI AIMEE KARAM DAPHNA LEVINSON MARIA ELENA MEDINA MORA MARK A OAKLEY BROWNE JOSé POSADA-VILLA DAN J STEIN CHEUK HIM ADLEY TSANG SERGIO AGUILAR-GAXIOLA JORDI ALONSO SING LEE STEVEN HEERINGA BETH-ELLEN PENNELL PATRICIA BERGLUND MICHAEL J GRUBER MARIA PETUKHOVA SOMNATH CHATTERJI T. BEDIRHAN üSTüN 《World psychiatry》2007,6(3):168-176
Data are presented on the lifetime prevalence, projected lifetime risk,
and age-of-onset distributions of mental disorders in the World Health Organization
(WHO)''s World Mental Health (WMH) Surveys. Face-to-face community surveys
were conducted in seventeen countries in Africa, Asia, the Americas, Europe,
and the Middle East. The combined numbers of respondents were 85,052. Lifetime
prevalence, projected lifetime risk, and age of onset of DSM-IV disorders
were assessed with the WHO Composite International Diagnostic Interview (CIDI),
a fully-structured lay administered diagnostic interview. Survival analysis
was used to estimate lifetime risk. Median and inter-quartile range (IQR)
of age of onset is very early for some anxiety disorders (7-14, IQR: 8-11)
and impulse control disorders (7-15, IQR: 11-12). The age-of-onset distribution
is later for mood disorders (29-43, IQR: 35-40), other anxiety disorders (24-50,
IQR: 31-41), and substance use disorders (18-29, IQR: 21-26). Median and IQR
lifetime prevalence estimates are: anxiety disorders 4.8-31.0% (IQR: 9.9-16.7%),
mood disorders 3.3-21.4% (IQR: 9.8-15.8%), impulse control disorders 0.3-25.0%
(IQR: 3.1-5.7%), substance use disorders 1.3-15.0% (IQR: 4.8-9.6%), and any
disorder 12.0-47.4% (IQR: 18.1-36.1%). Projected lifetime risk is proportionally
between 17% and 69% higher than estimated lifetime prevalence (IQR: 28-44%),
with the highest ratios in countries exposed to sectarian violence (Israel,
Nigeria, and South Africa), and a general tendency for projected risk to be
highest in recent cohorts in all countries. These results document clearly
that mental disorders are commonly occurring. As many mental disorders begin
in childhood or adolescents, interventions aimed at early detection and treatment
might help reduce the persistence or severity of primary disorders and prevent
the subsequent onset of secondary disorders. 相似文献
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CATHRYN H. GREENBERG AIMEE LIVINGS TOMCHO J. DREW LANHAM THOMAS A. WALDROP JOSEPH TOMCHO ROSS J. PHILLIPS DEAN SIMON 《The Journal of wildlife management》2007,71(6):1906-1916
Abstract: We compared the effects of 3 fuel reduction techniques and a control on breeding birds during 2001-2005 using 50-m point counts. Four experimental units, each >14 ha, were contained within each of 3 replicate blocks at the Green River Game Land, Polk County, North Carolina, USA. Treatments were 1) prescribed burn, 2) mechanical understory reduction (chainsaw-felling of shrubs and small trees), 3) mechanical + burn, and 4) controls. We conducted mechanical treatments in winter 2001-2002 and prescribed burns in spring 2003. Tall shrub cover was substantially reduced in all treatments compared to controls. Tree mortality and canopy openness was highest in the mechanical + burn treatment after burning, likely due to higher fuel loading and hotter burns; tree mortality increased with time. Many bird species did not detectably decrease or increase in response to treatments. Species richness, total bird density, and some species, including indigo buntings (Passerina cyanea) and eastern bluebirds (Sialia sialis), increased in the mechanical + burn treatment after a 1-year to 2-year delay; eastern woodpewees (Contopus virens) increased immediately after treatment. Hooded warblers (Wilsonia citrina), black-and-white warblers (Mniotilta varia), and worm-eating warblers (Helmitheros vermivorus) declined temporarily in some or all treatments, likely in response to understory and (or) leaf litter depth reductions. Densities of most species affected by treatments varied with shrub cover, tree or snag density, or leaf litter depth. High snag availability, open conditions, and a higher density of flying insects in the mechanical + burn treatment likely contributed to increased bird density and species richness. In our study, fuel reduction treatments that left the canopy intact, such as low-intensity prescribed fire or mechanical understory removal, had few detectable effects on breeding birds compared to the mechanical + burn treatment. High-intensity burning with heavy tree-kill, as occurred in our mechanical + burn treatment, can be used as a management tool to increase densities of birds associated with open habitat while retaining many forest and generalist species, but may have short-term adverse effects on some species that are associated with the ground- or shrub-strata for nesting and foraging. 相似文献
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