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1.
J Public Health (Oxf) ; 45(1): 36-39, 2023 03 14.
Artículo en Inglés | MEDLINE | ID: mdl-35077546

RESUMEN

INTRODUCTION: Political polarization has increased in the USA within recent years. Studies have shown Republicans are less likely to accept COVID-19 vaccinations than Democrats; however, little is known regarding the association between COVID-19 vaccination acceptance and political polarization. METHODS: We used data from a nationally-representative survey of 1427 participants conducted between 9 February 2021 and 17 February 2021. We estimated multivariate-adjusted odds ratios for COVID-19 vaccination intent and receipt according to perceived political polarization (measured as the perceived size of the ideological gap between Democrats and Republicans), political party affiliation, and social trust, controlling for demographic and socioeconomic factors. RESULTS: Among participants perceiving high levels of polarization, Republicans (versus Democrats) reported a 90% lower odds of vaccination intent (OR = 0.10 [0.05, 0.19], P < 0.001). Participants with high (versus low) social trust and low perceived polarization had a 2-folder higher vaccination intent (OR = 2.39 [1.34, 4.21], P = 0.003); this association was substantially weaker in the high perceived polarization group. CONCLUSIONS: High perceived levels of political polarization appear to magnify the decrease in the odds of receiving the COVID-19 vaccine and the intent to get vaccinated among Republicans versus Democrats. Political polarization may further attenuate the protective associations of high social capital with vaccination.


Asunto(s)
Vacunas contra la COVID-19 , COVID-19 , Humanos , Vacunas contra la COVID-19/uso terapéutico , Confianza , Política , COVID-19/epidemiología , COVID-19/prevención & control , Intención
2.
Front Psychiatry ; 12: 640741, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34025472

RESUMEN

Background: Digital technologies have the potential to provide objective and precise tools to detect depression-related symptoms. Deployment of digital technologies in clinical research can enable collection of large volumes of clinically relevant data that may not be captured using conventional psychometric questionnaires and patient-reported outcomes. Rigorous methodology studies to develop novel digital endpoints in depression are warranted. Objective: We conducted an exploratory, cross-sectional study to evaluate several digital technologies in subjects with major depressive disorder (MDD) and persistent depressive disorder (PDD), and healthy controls. The study aimed at assessing utility and accuracy of the digital technologies as potential diagnostic tools for unipolar depression, as well as correlating digital biomarkers to clinically validated psychometric questionnaires in depression. Methods: A cross-sectional, non-interventional study of 20 participants with unipolar depression (MDD and PDD/dysthymia) and 20 healthy controls was conducted at the Centre for Human Drug Research (CHDR), the Netherlands. Eligible participants attended three in-clinic visits (days 1, 7, and 14), at which they underwent a series of assessments, including conventional clinical psychometric questionnaires and digital technologies. Between the visits, there was at-home collection of data through mobile applications. In all, seven digital technologies were evaluated in this study. Three technologies were administered via mobile applications: an interactive tool for the self-assessment of mood, and a cognitive test; a passive behavioral monitor to assess social interactions and global mobility; and a platform to perform voice recordings and obtain vocal biomarkers. Four technologies were evaluated in the clinic: a neuropsychological test battery; an eye motor tracking system; a standard high-density electroencephalogram (EEG)-based technology to analyze the brain network activity during cognitive testing; and a task quantifying bias in emotion perception. Results: Our data analysis was organized by technology - to better understand individual features of various technologies. In many cases, we obtained simple, parsimonious models that have reasonably high diagnostic accuracy and potential to predict standard clinical outcome in depression. Conclusion: This study generated many useful insights for future methodology studies of digital technologies and proof-of-concept clinical trials in depression and possibly other indications.

3.
Bioanalysis ; 12(16): 1117-1127, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32885989

RESUMEN

Outsourcing is a common strategy across the pharmaceutical industry and clinical research. CROs offer many choices for selecting outsourcing partners for bioanalytical and biomarker support. We aimed this paper to provide critical insights into CRO benchmarking and selection using a bioanalytical challenge approach performing fit-for-purpose ligand-binding assay. Bioanalytical challenge (method validation and sample analysis) offer Pharma sponsors a great opportunity to stress test CRO technical and scientific competency, quality systems and operational capabilities. In addition, CROs demonstrated their real-life performance in communication, time management and cost - key contributors to a successful sponsor-CRO partnership. Benchmarking CROs based on objective assay data and real-life experiences will help sponsors to make better-informed decisions in vendor selection.


Asunto(s)
Benchmarking/métodos , Bioensayo/métodos , Biomarcadores/metabolismo , Humanos
4.
PLoS One ; 13(11): e0206801, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30395621

RESUMEN

Myocilin (MYOC) is the gene with mutations most common in glaucoma. In the eye, MYOC is in trabecular meshwork, ciliary body, and retina. Other tissues with high MYOC transcript levels are skeletal muscle and heart. To date, the function of wild-type MYOC remains unknown and how mutant MYOC causes high intraocular pressure and glaucoma is ambiguous. By investigating mutant MYOC in a non-ocular tissue we hoped to obtain novel insight into mutant MYOC pathology. For this study, we utilized a transgenic mouse expressing human mutant MYOC Y437H protein and we examined its skeletal (gastrocnemius) muscle phenotype. Electron micrographs showed that sarcomeres in the skeletal muscle of mutant CMV-MYOC-Y437H mice had multiple M-bands. Western blots of soluble muscle lysates from transgenics indicated a decrease in two M-band proteins, myomesin 1 (MYOM1) and muscle creatine kinase (CKM). Immunoprecipitation identified CKM as a MYOC binding partner. Our results suggest that binding of mutant MYOC to CKM is changing sarcomere ultrastructure and this may adversely impact muscle function. We speculate that a person carrying the mutant MYOC mutation will likely have a glaucoma phenotype and may also have undiagnosed muscle ailments or vice versa, both of which will have to be monitored and treated.


Asunto(s)
Proteínas del Citoesqueleto/genética , Proteínas del Ojo/genética , Glaucoma de Ángulo Abierto/genética , Glaucoma de Ángulo Abierto/patología , Glicoproteínas/genética , Músculo Esquelético/metabolismo , Músculo Esquelético/ultraestructura , Mutación , Sarcómeros/genética , Sarcómeros/ultraestructura , Animales , Proteínas del Citoesqueleto/metabolismo , Modelos Animales de Enfermedad , Proteínas del Ojo/metabolismo , Femenino , Expresión Génica , Glaucoma de Ángulo Abierto/metabolismo , Glicoproteínas/metabolismo , Humanos , Presión Intraocular/genética , Masculino , Ratones , Ratones Mutantes , Ratones Transgénicos , Microscopía Electrónica de Transmisión , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Miocardio/metabolismo , Fenotipo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Sarcómeros/metabolismo , Malla Trabecular/metabolismo , Malla Trabecular/ultraestructura
5.
BMC Musculoskelet Disord ; 17: 284, 2016 07 13.
Artículo en Inglés | MEDLINE | ID: mdl-27412526

RESUMEN

BACKGROUND: Patients with painful knee osteoarthritis (OA) demonstrate hyperalgesia and altered pain-modulatory responses. While some prior work has demonstrated cross-sectional associations between laboratory and clinical pain measures, it is unknown whether individual variability in quantitative sensory testing (QST) responses at baseline can prospectively predict analgesic treatment responses. METHOD: Patients with knee OA (n = 35) were compared on QST responses to a demographically-matched pain-free control group (n = 39), after which patients completed a month-long treatment study of diclofenac sodium topical gel (1 %), applied up to 4 times daily. RESULTS: OA patients demonstrated reduced pain thresholds at multiple anatomic sites, as well as reduced conditioned pain modulation (CPM) and enhanced temporal summation of pain. The most pain-sensitive patients tended to report the most intense and neuropathic OA pain. Following diclofenac treatment, the knee OA cohort showed a roughly 30 % improvement in pain, regardless of the presence or absence of neuropathic symptoms. Baseline CPM scores, an index of endogenous pain-inhibitory capacity, were prospectively associated with treatment-related changes in clinical pain. Specifically, participants with higher CPM at baseline (i.e., better functioning endogenous pain-inhibitory systems) showed more reduction in pain at the end of treatment (p < .05). CONCLUSIONS: These results support prior findings of amplified pain sensitivity and reduced pain-inhibition in OA patients. Moreover, the moderate to strong associations between laboratory-based measures of pain sensitivity and indices of clinical pain highlight the clinical relevance of QST in this sample. Finally, the prospective association between CPM and diclofenac response suggests that QST-based phenotyping may have utility in explaining inter-patient variability in long-term analgesic treatment outcomes. TRIAL REGISTRATION: ClinicalTrials.Gov Identifier: NCT01383954 . Registered June 22, 2011.


Asunto(s)
Antiinflamatorios no Esteroideos/uso terapéutico , Diclofenaco/uso terapéutico , Hiperalgesia/tratamiento farmacológico , Osteoartritis de la Rodilla/tratamiento farmacológico , Manejo del Dolor/métodos , Umbral del Dolor/efectos de los fármacos , Administración Tópica , Antiinflamatorios no Esteroideos/administración & dosificación , Estudios de Casos y Controles , Diclofenaco/administración & dosificación , Femenino , Geles , Humanos , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/complicaciones , Dolor/etiología , Dimensión del Dolor , Resultado del Tratamiento
6.
Anesthesiology ; 123(4): 861-72, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26375824

RESUMEN

BACKGROUND: Opioids are frequently prescribed for chronic low back pain (CLBP), but there are little prospective data on which patient subgroups may benefit. Psychiatric comorbidity, such as high levels of depression and anxiety symptoms (termed comorbid negative affect [NA]), is a common presentation and may predict diminished opioid analgesia and/or increased opioid misuse. METHODS: The authors conducted a 6½-month prospective cohort study of oral opioid therapy, with an active drug/placebo run-in period, in 81 CLBP patients with low, moderate, and high levels of NA. Treatment included an opioid titration phase with a prescribing physician blinded to NA group assignment and a 4-month continuation phase, during which subjects recorded daily pain levels using an electronic diary. The primary outcome was the percent improvement in average daily pain, summarized weekly. RESULTS: There was an overall 25% dropout rate. Despite the high NA group being prescribed a higher average daily dose of morphine equivalents, linear mixed model analysis revealed that the 24 study completers in each of the high NA and low NA groups had an average 21 versus 39% improvement in pain, respectively (P < 0.01). The high NA group also had a significantly greater rate of opioid misuse (39 vs. 8%, P < 0.05) and significantly more and intense opioid side effects (P < 0.01). CONCLUSIONS: These results indicate that the benefit and risk considerations in CLBP patients with high NA versus low NA are distinctly different. Thus, NA is an important phenotypic variable to characterize at baseline, before deciding whether to prescribe opioids for CLBP.


Asunto(s)
Analgésicos Opioides/uso terapéutico , Dolor Crónico/diagnóstico , Dolor de la Región Lumbar/diagnóstico , Trastornos Mentales/diagnóstico , Trastornos Relacionados con Opioides/diagnóstico , Analgésicos Opioides/farmacología , Dolor Crónico/tratamiento farmacológico , Dolor Crónico/psicología , Estudios de Cohortes , Comorbilidad , Estudios Cruzados , Diagnóstico Dual (Psiquiatría) , Método Doble Ciego , Femenino , Humanos , Dolor de la Región Lumbar/tratamiento farmacológico , Dolor de la Región Lumbar/psicología , Masculino , Trastornos Mentales/tratamiento farmacológico , Trastornos Mentales/psicología , Persona de Mediana Edad , Trastornos Relacionados con Opioides/psicología , Dimensión del Dolor/efectos de los fármacos , Dimensión del Dolor/métodos , Estudios Prospectivos
7.
Pain ; 156(6): 1092-1100, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25782367

RESUMEN

The primary purpose of this study was to examine the association between self-reports of medication side effects and pain-related activity interference in patients with chronic pain. The potential moderators of the association between reports of side effects and pain-related activity interference were also examined. A total of 111 patients with chronic musculoskeletal pain were asked to provide, once a month for a period of 6 months, self-reports of medication use and the presence of any perceived side effects (eg, nausea, dizziness, headaches) associated with their medications. At each of these time points, patients were also asked to provide self-reports of pain intensity, negative affect, and pain-related activity interference. Multilevel modeling analyses revealed that month-to-month increases in perceived medication side effects were associated with heightened pain-related activity interference (P < 0.05). Importantly, multilevel models revealed that perceived medication side effects were associated with heightened pain-related activity interference even after controlling for the influence of patient demographics, pain intensity, and negative affect. This study provides preliminary evidence that reports of medication side effects are associated with heightened pain-related activity interference in patients with chronic pain beyond the influence of other pain-relevant variables. The implications of our findings for clinical practice and the management of patients with chronic pain conditions are discussed.


Asunto(s)
Analgésicos/efectos adversos , Dolor Crónico , Terapia Cognitivo-Conductual/métodos , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Autoinforme , Adulto , Antiinflamatorios no Esteroideos/efectos adversos , Dolor Crónico/tratamiento farmacológico , Dolor Crónico/psicología , Dolor Crónico/rehabilitación , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Dimensión del Dolor , Trastornos Relacionados con Sustancias/etiología
8.
PLoS One ; 9(4): e96065, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24755935

RESUMEN

To identify the seasonal pattern of nitrogen (N) and phosphorus (P) limitation of phytoplankton in four different lakes, biweekly experiments were conducted from the end of March to September 2011. Lake water samples were enriched with N, P or both nutrients and incubated under two different light intensities. Chlorophyll a fluorescence (Chla) was measured and a model selection procedure was used to assign bioassay outcomes to different limitation categories. N and P were both limiting at some point. For the shallow lakes there was a trend from P limitation in spring to N or light limitation later in the year, while the deep lake remained predominantly P limited. To determine the ability of in-lake N:P ratios to predict the relative strength of N vs. P limitation, three separate regression models were fit with the log-transformed ratio of Chla of the P and N treatments (Response ratio = RR) as the response variable and those of ambient total phosphorus:total nitrogen (TN:TP), dissolved inorganic nitrogen:soluble reactive phosphorus (DIN:SRP), TN:SRP and DIN:TP mass ratios as predictors. All four N:P ratios had significant positive relationships with RR, such that high N:P ratios were associated with P limitation and low N:P ratios with N limitation. The TN:TP and DIN:TP ratios performed better than the DIN:SRP and TN:SRP in terms of misclassification rate and the DIN:TP ratio had the highest R2 value. Nitrogen limitation was predictable, frequent and persistent, suggesting that nitrogen reduction could play a role in water quality management. However, there is still uncertainty about the efficacy of N restriction to control populations of N2 fixing cyanobacteria.


Asunto(s)
Lagos/química , Nitrógeno/química , Fósforo/química , Clorofila/metabolismo , Clorofila A , Cianobacterias/metabolismo , Alemania , Nitrógeno/metabolismo , Fósforo/metabolismo , Fitoplancton/metabolismo , Estaciones del Año
9.
Clin J Pain ; 30(10): 839-45, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24135900

RESUMEN

AIMS/OBJECTIVES/BACKGROUND: Studies have associated chronic low back pain (cLBP) with grey matter thinning. But these studies have not controlled for important clinical variables (such as a comorbid affective disorder, pain medication, age, or pain phenotype), which may reduce or eliminate these associations. METHODS: We conducted cortical thickness and voxel-based morphometry (VBM) analyses in 14 cLBP patients with a discogenic component to their pain, not taking opioids or benzodiazepines, and not depressed or anxious. They were age and gender matched to 14 pain-free controls (PFCs). An ROI-driven analysis (regions of interest) was conducted, using 18 clusters from a previous arterial spin labeling study demonstrating greater regional cerebral blood flow (rCBF) in these cLBP subjects than the PFCs. Cortical thickness and VBM-based gray matter volume measurements were obtained from a structural MRI scan and group contrasts were calculated. RESULTS: Multivariate analysis of variance showed a trend toward cortical thickening in the right paracentral lobule in cLBP subjects (F1,17=3.667, P<0.067), and significant thickening in the right rostral middle frontal gyrus (F1,17=6.880, P<0.014). These clusters were non-significant after including age as a covariate (P<0.891; P<0.279). A whole-brain cortical thickness and VBM analysis also did not identify significant clusters of thinning or thickening. Exploratory analyses identified group differences for correlations between age and cortical thickness of the right rostral middle frontal gyrus (cLBP: R=-0.03, P=0.9; PFCs: R=-0.81, P<0.001), that is, PFCs demonstrated age-related thinning while cLBP patients did not. CONCLUSIONS: Our pilot results suggest that controlling for affect, age, and concurrent medications may reduce or eliminate some of the previously reported structural brain alterations in cLBP.


Asunto(s)
Corteza Cerebral/patología , Sustancia Gris/patología , Dolor de la Región Lumbar/patología , Dolor de la Región Lumbar/psicología , Fenotipo , Adulto , Anciano , Estudios de Casos y Controles , Corteza Cerebral/irrigación sanguínea , Enfermedad Crónica , Evaluación de la Discapacidad , Femenino , Estudios de Seguimiento , Humanos , Procesamiento de Imagen Asistido por Computador , Dolor de la Región Lumbar/complicaciones , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Trastornos del Humor/etiología , Dimensión del Dolor , Escalas de Valoración Psiquiátrica
10.
J Pain ; 15(1): 90-100, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24295876

RESUMEN

UNLABELLED: Over the past decade, considerable research has accumulated showing that chronic pain patients experiencing high levels of negative affect (NA) are at increased risk for prescription opioid misuse. The primary objective of the present study was to examine the factors that underlie the association between NA and prescription opioid misuse among patients with chronic pain. In this study, 82 patients with chronic musculoskeletal pain being prescribed opioid medication completed the Current Opioid Misuse Measure, a well-validated self-report questionnaire designed to assess prescription opioid misuse. Patients were also asked to complete self-report measures of pain intensity, NA, and opioid craving. A bootstrapped multiple mediation analysis was used to examine the mediating role of patients' pain intensity and opioid craving in the association between NA and prescription opioid misuse. Consistent with previous research, we found a significant association between NA and prescription opioid misuse. Interestingly, results revealed that opioid craving, but not pain intensity, mediated the association between NA and opioid misuse. The Discussion addresses the potential psychological and neurobiological factors that might contribute to the interrelationships among NA, opioid craving, and prescription opioid misuse in patients with pain. The clinical implications of our findings are also discussed. PERSPECTIVE: Our study provides new insights into the factors that underlie the association between negative affect and prescription opioid misuse in patients with chronic pain. Our findings could have important clinical implications, particularly for patients being prescribed opioid medication, and for reducing rates of opioid misuse in patients with pain.


Asunto(s)
Analgésicos Opioides/efectos adversos , Trastornos Relacionados con Opioides/etiología , Trastornos Relacionados con Opioides/psicología , Adulto , Dolor Crónico/tratamiento farmacológico , Comportamiento de Búsqueda de Drogas , Femenino , Humanos , Masculino , Persona de Mediana Edad , Trastornos Relacionados con Opioides/rehabilitación , Dimensión del Dolor , Medicamentos bajo Prescripción/efectos adversos , Autoinforme , Estadística como Asunto , Encuestas y Cuestionarios
11.
PLoS One ; 7(6): e38757, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22719937

RESUMEN

The importance of nitrogen (N) versus phosphorus (P) in explaining total cyanobacterial biovolume, the biovolume of specific cyanobacterial taxa, and the incidence of cyanotoxins was determined for 102 north German lakes, using methods to separate the effects of joint variation in N and P concentration from those of differential variation in N versus P. While the positive relationship between total cyanobacteria biovolume and P concentration disappeared at high P concentrations, cyanobacteria biovolume increased continually with N concentration, indicating potential N limitation in highly P enriched lakes. The biovolumes of all cyanobacterial taxa were higher in lakes with above average joint NP concentrations, although the relative biovolumes of some Nostocales were higher in less enriched lakes. Taxa were found to have diverse responses to differential N versus P concentration, and the differences between taxa were not consistent with the hypothesis that potentially N(2)-fixing Nostocales taxa would be favoured in low N relative to P conditions. In particular Aphanizomenon gracile and the subtropical invasive species Cylindrospermopsis raciborskii often reached their highest biovolumes in lakes with high nitrogen relative to phosphorus concentration. Concentrations of all cyanotoxin groups increased with increasing TP and TN, congruent with the biovolumes of their likely producers. Microcystin concentration was strongly correlated with the biovolume of Planktothrix agardhii but concentrations of anatoxin, cylindrospermopsin and paralytic shellfish poison were not strongly related to any individual taxa. Cyanobacteria should not be treated as a single group when considering the potential effects of changes in nutrient loading on phytoplankton community structure and neither should the N(2)-fixing Nostocales. This is of particular importance when considering the occurrence of cyanotoxins, as the two most abundant potentially toxin producing Nostocales in our study were found in lakes with high N relative to P enrichment.


Asunto(s)
Toxinas Bacterianas/metabolismo , Cianobacterias/metabolismo , Nitrógeno/metabolismo , Fósforo/metabolismo , Microbiología del Agua
12.
PLoS One ; 6(3): e17516, 2011 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-21423742

RESUMEN

Coral reef ecosystems worldwide are under pressure from chronic and acute stressors that threaten their continued existence. Most obvious among changes to reefs is loss of hard coral cover, but a precise multi-scale estimate of coral cover dynamics for the Great Barrier Reef (GBR) is currently lacking. Monitoring data collected annually from fixed sites at 47 reefs across 1300 km of the GBR indicate that overall regional coral cover was stable (averaging 29% and ranging from 23% to 33% cover across years) with no net decline between 1995 and 2009. Subregional trends (10-100 km) in hard coral were diverse with some being very dynamic and others changing little. Coral cover increased in six subregions and decreased in seven subregions. Persistent decline of corals occurred in one subregion for hard coral and Acroporidae and in four subregions in non-Acroporidae families. Change in Acroporidae accounted for 68% of change in hard coral. Crown-of-thorns starfish (Acanthaster planci) outbreaks and storm damage were responsible for more coral loss during this period than either bleaching or disease despite two mass bleaching events and an increase in the incidence of coral disease. While the limited data for the GBR prior to the 1980's suggests that coral cover was higher than in our survey, we found no evidence of consistent, system-wide decline in coral cover since 1995. Instead, fluctuations in coral cover at subregional scales (10-100 km), driven mostly by changes in fast-growing Acroporidae, occurred as a result of localized disturbance events and subsequent recovery.


Asunto(s)
Antozoos/crecimiento & desarrollo , Conservación de los Recursos Naturales , Arrecifes de Coral , Animales , Australia , Dinámica Poblacional , Factores de Tiempo
13.
Curr Biol ; 18(12): R514-5, 2008 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-18579091

RESUMEN

No-take marine reserves (NTMRs) are much advocated as a solution to managing marine ecosystems, protecting exploited species and restoring natural states of biodiversity [1,2]. Increasingly, it is becoming clear that effective marine conservation and management at ecosystem and regional scales requires extensive networks of NTMRs [1,2]. The world's largest network of such reserves was established on Australia's Great Barrier Reef (GBR) in 2004. Closing such a large area to all fishing has been socially and politically controversial, making it imperative that the effectiveness of this new reserve network be assessed. Here we report evidence, first, that the densities of the major target species of the GBR reef line fisheries were significantly higher in the new NTMRs, compared with fished sites, in just two years; and second, that the positive differences were consistent for multiple marine reserves over an unprecedented spatial scale (>1,000 km).


Asunto(s)
Antozoos/fisiología , Conservación de los Recursos Naturales , Perciformes/fisiología , Animales , Australia , Biodiversidad , Ecosistema , Biología Marina , Océanos y Mares , Densidad de Población , Evaluación de Programas y Proyectos de Salud , Especificidad de la Especie , Factores de Tiempo
14.
BMC Ecol ; 4: 8, 2004 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-15176982

RESUMEN

BACKGROUND: Explanations for patterns observed in the structure of local assemblages are frequently sought with reference to interactions between species, and between species and their local environment. However, analyses of null models, where non-interactive local communities are assembled from regional species pools, have demonstrated that much of the structure of local assemblages remains in simulated assemblages where local interactions have been excluded. Here we compare the ability of two null models to reproduce the breeding bird community of Eastern Wood, a 16-hectare woodland in England, UK. A random draw model, in which there is complete annual replacement of the community by immigrants from the regional pool, is compared to a locally neutral community model, in which there are two additional parameters describing the proportion of the community replaced annually (per capita death rate) and the proportion of individuals recruited locally rather than as immigrants from the regional pool. RESULTS: Both the random draw and locally neutral model are capable of reproducing with significant accuracy several features of the observed structure of the annual Eastern Wood breeding bird community, including species relative abundances, species richness and species composition. The two additional parameters present in the neutral model result in a qualitatively more realistic representation of the Eastern Wood breeding bird community, particularly of its dynamics through time. The fact that these parameters can be varied, allows for a close quantitative fit between model and observed communities to be achieved, particularly with respect to annual species richness and species accumulation through time. CONCLUSION: The presence of additional free parameters does not detract from the qualitative improvement in the model and the neutral model remains a model of local community structure that is null with respect to species differences at the local scale. The ability of this locally neutral model to describe a larger number of woodland bird communities with either little variation in its parameters or with variation explained by features local to the woods themselves (such as the area and isolation of a wood) will be a key subsequent test of its relevance.


Asunto(s)
Aves/clasificación , Aves/fisiología , Ecosistema , Modelos Biológicos , Árboles , Animales , Inglaterra
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