Ecology Letters (2010) 13: 675–684
Community assembly history is increasingly recognized as a fundamental determinant of community structure. However, little is known as to how assembly history may ...affect ecosystem functioning via its effect on community structure. Using wood‐decaying fungi as a model system, we provide experimental evidence that large differences in ecosystem functioning can be caused by small differences in species immigration history during community assembly. Direct manipulation of early immigration history resulted in three‐fold differences in fungal species richness and composition and, as a consequence, differences of the same magnitude in the rate of decomposition and carbon release from wood. These effects – which were attributable to the history‐dependent outcome of competitive and facilitative interactions – were significant across a range of nitrogen availabilities observed in natural forests. Our results highlight the importance of considering assembly history in explaining ecosystem functioning.
Ecology Letters (2011)
Assembly history, or the order of species arrival, can have wide‐ranging effects on species, communities and ecosystems. However, it remains unclear whether assembly history ...primarily affects individual species, with effects attenuating at the level of communities and ecosystems or, alternatively, has consistent effect sizes across increasing levels of ecological organisation. We address this question using a field‐based manipulation of assembly history of wood‐inhabiting fungi. The largest effect sizes were observed for the frequency of some individual species, and mean effect sizes were lower for community metrics of fungi immigrating from the regional species pool. There was little evidence, however, of attenuation in effect sizes at the ecosystem level (carbon, nitrogen, decomposition) in comparison to the species or community level. These results indicate that assembly history can have strong effects on ecosystem properties even under natural levels of environmental variability.
Both top‐down (grazing) and bottom‐up (resource availability) forces can determine the strength of priority effects, or the effects of species arrival history on the structure and function of ...ecological communities, but their combined influences remain unresolved. To test for such influences, we assembled experimental communities of wood‐decomposing fungi using a factorial manipulation of fungivore (Folsomia candida) presence, nitrogen availability, and fungal assembly history. We found interactive effects of all three factors on fungal species composition and wood decomposition 1 year after the fungi were introduced. The strength of priority effects on community structure was affected primarily by nitrogen availability, whereas the strength of priority effects on decomposition rate was interactively regulated by nitrogen and fungivores. These results demonstrate that top‐down and bottom‐up forces jointly determine how strongly assembly history affects community structure and function.
sensu lato has recently been intensively studied in China and South America, and four independent clades representing four genera have been recognized phylogenetically. In this study, more samples, ...mostly from subtropical and tropical Asia, Oceania, and East Africa, are analyzed. A phylogeny based on a 4-gene dataset of sequences (ITS + nLSU + mtSSU +
) has confirmed the presence of four genera in
sensu lato:
, and
sensu stricto. Six new species,
, and
, are described based on morphology and phylogenetic analysis. Three new combinations are proposed, viz.
, and
. To date, 36 species of
sensu lato are accepted and an identification key to these species is provided. In addition, the identification of
, and
is discussed.
Chaucer's Troilus and Criseyde puts perspective itself under the microscope: throughout, the individual experience of reading the world is brought into the foreground as sense-perception, and the ...immediate experience of time, are rendered with a striking psychological verisimilitude. This essay breaks with the critical orthodoxy around this poem, which sees the poem's dynamics of temporal perspectives as a structural analogue with Boethius' philosophy of time and free will-one which places the reader 'in God's shoes' by providing advance knowledge of the poem's end. Challenging this notion, this essay argues that the poem's complex interplay of individual perspectives actually reveals the total contingency of the readerly vantage-point, exposing the 'situatedness in time' of reader and text. Rather than being a cipher for Boethian philosophy, I argue that Troilus and Criseyde advances a Chaucerian phenomenology of reading-one that is as metapoetic as it is metaphysical, concerning both semantic indeterminacy and the temporality of individual experience. This approach brings Chaucer into productive, and largely untapped, dialogues with modern philosophers and contemporary theoretical currents, including recent advances considering literature and contingency.
Paediatric disorders of pulmonary surfactant may occur due to mutations involving surfactant proteins B and C, and ATP‐binding cassette subfamily A member 3 (ABCA3) genes. Recessive frameshift or ...nonsense ABCA3 mutations are associated with respiratory failure and neonatal death but milder phenotypes of ABCA3 deficiency due to missense, splice site, and insertion/deletions may result in survival beyond infancy. To date, only one case report describes the clinical course from birth to age 21 years and there are less than 10 adult cases. No guidelines exist for medical therapy due to the rarity of this condition. We describe the clinical course of a patient over 39 years and her younger brother who were both diagnosed at birth with an unspecified paediatric interstitial lung disease (ILD) and were eventually diagnosed with ABCA3 mutation in their adulthood. Our report highlights the minimal progression of the ABCA3‐related ILD without long‐term medications, but the development of dyspnoea due to progressive pulmonary hypertension and airflow obstruction.
We describe the clinical progress of siblings who initially presented with an undifferentiated paediatric interstitial lung disease at birth which was eventually diagnosed in adulthood as pulmonary surfactant dysfunction due to ATP‐binding cassette subfamily A member 3 (ABCA3) mutations. Clinical deterioration was due to progressive pulmonary hypertension and a moderate decline in forced expiratory volume in 1 sec (FEV1), rather than progression of the interstitial lung disease.
Ethnicity and obstructive sleep apnoea Villaneuva, Anna Tessa C.; Buchanan, Peter R.; Yee, Brendon J. ...
Sleep medicine reviews,
12/2005, Letnik:
9, Številka:
6
Journal Article
Recenzirano
There is a scarcity of adult prevalence studies of OSA outside the Caucasian populations of North America, Europe and Australia, and comparisons have been complicated by methodological differences in ...sleep study settings, respiratory events definition, measured risk factors and clinical outcomes, and the lack of objective parameters for the measurement of ethnicity itself. Comparing studies with the same methodological design and respiratory events definition, recent large-scale prevalence studies from Hong Kong, Korea and India show similar OSA rates to populations of mainly Caucasian composition. OSA is a very complex disorder determined by several phenotypes such as obesity, craniofacial structure and abnormalities in neuromuscular and ventilatory control. Genetics may partially explain some of the ethnic clustering of these phenotypes, modulated by cultural and environmental factors. The exact contribution of these component phenotypes to overall OSA risk will be determined by their varying prevalence and relative risk conferred across ethnic groups. For lesser degrees of obesity, Asians are at risk for a more severe degree of illness compared with Caucasians. Inter-ethnic studies suggests that African–American ethnicity may also be a significant risk factor for OSA. The increased prevalences of OSA among American Indians and Hispanic adults, and increased severity among Pacific Islanders and Maoris, were mainly explained by increased obesity parameters. Most cephalometric studies have largely been conducted without specific regard to ethnicity and comparisons of findings across studies have been mainly limited by differences in sampling methods and the varying selection and definition of measured cephalometric variables. The limited number of studies with inter-ethnic comparative data suggest cephalometric variables and their degree of contribution to OSA vary across ethnic groups.
Mirtazapine is an a2A antagonist and mixed 5-HT2/5-HT3 antagonist that has been proposed as a potential treatment for obstructive sleep apnea (OSA). A small, randomized, controlled trial has ...previously found an approximate halving in the severity of OSA with daily doses of 4.5 and 15 mg. We aimed to confirm and extend these findings in 2 randomized placebo-controlled, proof-of-concept trials.
Two randomized, double-blind, placebo-controlled trials of mirtazapine for OSA (apnea-hypopnea index 10-40/h). Study 1: 3-way crossover, dose-finding study testing the self-administration of mirtazapine (7.5, 15, 30, and/or 45 mg) or placebo 30 minutes prior to bedtime for 2 weeks at each dose. Twenty patients were randomly assigned to 1 of 6 different dose-sequence groups, with each patient exposed to a maximum of 3 doses. Study 2: 3-arm, randomized, parallel-group trial of mirtazapine at 15 mg or mirtazapine 15 mg + Compound CD0012 or placebo for 4 weeks in 65 patients with OSA.
Two patients withdrew from Study 1 after complaints of unacceptable lethargy. Fifteen patients were withdrawn from study 2, 7 after complaints of unacceptable lethargy or other side-effects. No measurement of sleep apnea improved due to mirtazapine in either study. Weight gain was significantly greater on mirtazapine than on placebo in both trials.
Mirtazapine did not improve sleep apnea in either trial. Mirtazapine caused weight gain, which may further worsen OSA. Therefore, mirtazapine is not recommended for the treatment of OSA.
Evidence-based screening tools are required for detection of daytime hypercapnia in high-risk patient populations.
To determine the validity of supine awake oximetry as a test for daytime hypercapnia ...and severe sleep disordered breathing (SDB) in super-obese patients.
This was a cross-sectional diagnostic test evaluation of super-obese adults (body mass index >50 kg/m
) presenting to Liverpool Hospital, Australia, between 2009 and 2015 for diagnostic polysomnography (PSG) and arterial blood gas measurement. Supine awake oxygen saturation (SpO
) was determined using oximetry measurements from the first three awake epochs of raw PSG data. Sensitivity and specificity of SpO
for detecting patients with daytime hypercapnia (PaCO
>45 mmHg) and severe SDB (respiratory disturbance index (RDI) >30 events/h) were assessed at various cut-off points and displayed using a receiver operating characteristic (ROC) curve. Area under the ROC curve and positive and negative predictive values (PPV and NPV) in the present patient population were derived.
Of 52 patients, 23 (44%) had daytime hypercapnia. SpO
measured awake in the supine position was associated with the presence of daytime hypercapnia but not with the presence of severe SDB. Overall, awake supine SpO
<91.2% had 34.8% sensitivity, 96.6% specificity and 88.8% PPV, and SpO
<96.7% had 87.0% sensitivity, 20.7% specificity and 66.7% NPV for the presence of daytime hypercapnia.
Awake supine oximetry is an easily performed test that may have novel use in identifying patients at high risk of respiratory failure. Future studies are required to evaluate prospectively its role in screening patients at risk of daytime hypercapnia.
In this study, the taxonomic diversity of the
species complex (
,
) is examined. Specimens were studied using an integrative taxonomic approach that includes molecular phylogenetic and morphological ...analyses, and environmental niche comparisons. Four different species were found inside the
complex, with a biogeographic distribution pattern bound by geographic regions: Europe, North America, Patagonia, and Australia-New Zealand. Molecular, morphological, and environmental evidences delimit two lineages within this complex: a Northern Hemisphere clade with longer basidiospores and wider ranges in temperature and precipitation tolerance, and a Southern Hemisphere clade with smaller and more spherical basidiospores, and an isothermal and more humid climate preference. The integrative taxonomic approach used in this study demonstrates congruence between data sets and shows how morphological and environmental characteristics contribute to the differentiation of fungal species complexes. By combining various sources of taxonomic information, three new species are described:
,
and
.
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