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Understanding the biogeographical patterns, and evolutionary and environmental drivers, underpinning morphological diversity are key for determining its origins and conservation. Using a comprehensive set of continuous morphological traits extracted from museum collections of 8353 bird species, including geometric morphometric beak shape data, we find that avian morphological diversity is unevenly distributed globally, even after controlling for species richness, with exceptionally dense packing of species in hyper-diverse tropical hotspots. At the regional level, these areas also have high morphological variance, with species exhibiting high phenotypic diversity. Evolutionary history likely plays a key role in shaping these patterns, with evolutionarily old species contributing to niche expansion, and young species contributing to niche packing. Taken together, these results imply that the tropics are both 'cradles' and 'museums' of phenotypic diversity.
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Biodiversidad , Aves , Animales , Pico , Evolución Biológica , FenotipoRESUMEN
Functional traits offer a rich quantitative framework for developing and testing theories in evolutionary biology, ecology and ecosystem science. However, the potential of functional traits to drive theoretical advances and refine models of global change can only be fully realised when species-level information is complete. Here we present the AVONET dataset containing comprehensive functional trait data for all birds, including six ecological variables, 11 continuous morphological traits, and information on range size and location. Raw morphological measurements are presented from 90,020 individuals of 11,009 extant bird species sampled from 181 countries. These data are also summarised as species averages in three taxonomic formats, allowing integration with a global phylogeny, geographical range maps, IUCN Red List data and the eBird citizen science database. The AVONET dataset provides the most detailed picture of continuous trait variation for any major radiation of organisms, offering a global template for testing hypotheses and exploring the evolutionary origins, structure and functioning of biodiversity.
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Aves , Ecosistema , Animales , Biodiversidad , Evolución Biológica , Humanos , FilogeniaRESUMEN
Evolution can involve periods of rapid divergent adaptation and expansion in the range of diversity, but evolution can also be relatively conservative over certain timescales due to functional, genetic-developmental, and ecological constraints. One way in which evolution may be conservative is in terms of allometry, the scaling relationship between the traits of organisms and body size. Here, we investigate patterns of allometric conservatism in the evolution of bird beaks with beak size and body size data for a representative sample of over 5000 extant bird species within a phylogenetic framework. We identify clades in which the allometric relationship between beak size and body size has remained relatively conserved across species over millions to tens of millions of years. We find that allometric conservatism is nonetheless punctuated by occasional shifts in the slopes and intercepts of allometric relationships. A steady accumulation of such shifts through time has given rise to the tremendous diversity of beak size relative to body size across birds today. Our findings are consistent with the Simpsonian vision of macroevolution, with evolutionary conservatism being the rule but with occasional shifts to new adaptive zones.
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Trapliners are pollinators that visit widely dispersed flowers along circuitous foraging routes. The evolution of traplining in hummingbirds is thought to entail morphological specialization through the reciprocal coevolution of longer bills with the long-tubed flowers of widely dispersed plant species. Specialization, such as that exhibited by traplining hummingbirds, is often viewed as both irreversible and an evolutionary dead end. We tested these predictions in a macroevolutionary framework. Specifically, we assessed the relationship between beak morphology and foraging and tested whether transitions to traplining are irreversible and lead to lower rates of diversification as predicted by the hypothesis that specialization is an evolutionary dead end. We find that there have been multiple independent transitions to traplining across the hummingbird phylogeny, but reversals have been rare or incomplete at best. Multiple independent lineages of trapliners have become morphologically specialized, convergently evolving relatively large bills for their body size. Traplining is not an evolutionary dead end however, since trapliners continue to give rise to new traplining species at a rate comparable to non-trapliners.
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Aves , Polinización , Animales , Aves/anatomía & histología , Flores/anatomía & histología , Filogenia , PlantasRESUMEN
This corrects the article DOI: 10.1038/nature21074.
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The origin and expansion of biological diversity is regulated by both developmental trajectories and limits on available ecological niches. As lineages diversify, an early and often rapid phase of species and trait proliferation gives way to evolutionary slow-downs as new species pack into ever more densely occupied regions of ecological niche space. Small clades such as Darwin's finches demonstrate that natural selection is the driving force of adaptive radiations, but how microevolutionary processes scale up to shape the expansion of phenotypic diversity over much longer evolutionary timescales is unclear. Here we address this problem on a global scale by analysing a crowdsourced dataset of three-dimensional scanned bill morphology from more than 2,000 species. We find that bill diversity expanded early in extant avian evolutionary history, before transitioning to a phase dominated by packing of morphological space. However, this early phenotypic diversification is decoupled from temporal variation in evolutionary rate: rates of bill evolution vary among lineages but are comparatively stable through time. We find that rare, but major, discontinuities in phenotype emerge from rapid increases in rate along single branches, sometimes leading to depauperate clades with unusual bill morphologies. Despite these jumps between groups, the major axes of within-group bill-shape evolution are remarkably consistent across birds. We reveal that macroevolutionary processes underlying global-scale adaptive radiations support Darwinian and Simpsonian ideas of microevolution within adaptive zones and accelerated evolution between distinct adaptive peaks.
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Pico/anatomía & histología , Evolución Biológica , Aves/fisiología , Animales , Colaboración de las Masas , Conjuntos de Datos como Asunto , Femenino , Masculino , Fenotipo , FilogeniaRESUMEN
This study aimed to explore multiple determinants of BMD (bone mineral density) in 99 women with long-standing type 1 diabetes, recruited from a population based register of insulin users. BMD was measured using DEXA (dual energy X-ray absorptiometry) at the femoral neck and lumbar spine, age adjusted Z scores were calculated and results compared to those of healthy volunteers. The median age of diabetic subjects was 42 years and the median duration of diabetes was 27 years. BMD was positively associated with body mass index and height at both the lumbar spine and femoral neck. There was a positive association with oral contraceptive pill use and lumbar spine BMD, and peripheral vascular disease was negatively associated with femoral neck BMD. No correlation was seen with either age or duration of diabetes and absolute BMD values. Mean Z score at the femoral neck was -0.12 (95% confidence interval -0.37 to +0.12). At the lumbar spine, the corresponding value was -0.21 (-0.44 to +0.02). Pre- and post-menopausal values for the diabetic subjects and healthy volunteers were found to be similar. In summary, axial BMD values in subjects with long-standing diabetes were similar to those observed in healthy non diabetic populations.
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Densidad Ósea/fisiología , Diabetes Mellitus Tipo 1/fisiopatología , Adulto , Anciano , Enfermedad Crónica , Factores de Confusión Epidemiológicos , Estudios Transversales , Femenino , Humanos , Persona de Mediana Edad , Osteoporosis/fisiopatología , Osteoporosis Posmenopáusica/fisiopatología , Premenopausia/fisiología , Valores de Referencia , Sistema de Registros , Factores de RiesgoRESUMEN
We have examined the effect of socioeconomic status (SES) on bone density (BMD) in 201 males, aged 20-60 years. Males of lower SES (groups 4-6 vs. 1-3) from the total sample had significantly higher BMD (p < 0.05) at L2-4 and femoral neck. The difference was small but was not explained by differences in age, weight, calcium intake, family history, activity, or smoking. 45% of SES 4-6 males were involved in manual labor compared with 11% of those in SES 1-3, however, this also did not appear to account for the difference.
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Densidad Ósea/fisiología , Cuello Femoral/fisiología , Vértebras Lumbares/fisiología , Clase Social , Población Blanca , Adulto , Factores de Edad , Análisis de Varianza , Peso Corporal/fisiología , Calcio de la Dieta/administración & dosificación , Estudios de Cohortes , Factores de Confusión Epidemiológicos , Humanos , Masculino , Persona de Mediana Edad , Ocupaciones , Aptitud Física , FumarRESUMEN
AIMS: To evaluate the effect of regular input by a geriatrician to an orthopaedic ward. METHOD: A geriatrician saw all patients aged over 65 years admitted to an acute orthopaedic ward-this was compared to an adjacent orthopaedic ward which had consultation only service, and also to both wards in the preceding year. All subjects over the age of 65 years with fractured neck of femur admitted over a 4 month period were enroled. Main outcome measures were length of stay, cost, discharge destination. RESULTS: In the year prior to study, patients in both wards had a mean total stay of 28 days. On the intervention ward the mean stay was reduced to 20.7 days, and on the control ward to 27 days. The cost per case on the intervention ward was NZ$9400, and on the control ward was NZ$11 500. Eleven percent went to a higher care level on the intervention ward, compared with 23% on the control ward. CONCLUSION: Geriatrician input on a twice weekly basis to all patients over 65 years of age on an orthopaedic ward, saves bed days, reduces costs and produces an improved outcome.
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Fracturas del Cuello Femoral/rehabilitación , Geriatría , Derivación y Consulta , Anciano , Anciano de 80 o más Años , Femenino , Fracturas del Cuello Femoral/economía , Evaluación Geriátrica , Humanos , Tiempo de Internación , Masculino , Resultado del TratamientoRESUMEN
AIMS: Bone mineral density (BMD) may be potentially reduced in Addison's disease as a result of excessive glucocorticoid replacement, loss of adrenal androgens or concomitant gonadal or thyroid disease. We have examined clinical and biochemical parameters, and BMD in a group of subjects with Addison's disease. METHODS: Fourteen patients (9 female mean age 56 years, 5 male mean age 56.6 years) with primary adrenocortical failure (median duration 8.5 yrs) on replacement therapy were studied. Four had hypothyroidism on thyroxine doses (0.1 to 0.15 mg/d). Seven of the 9 females were post menopausal. Mean plasma cortisol levels were calculated from at least five samples in each subject drawn between 3 and 5 hours post dose, and the cortisol replacement dose calculated per unit body mass (mg/kg). BMD was measured by dual energy X-ray absorptiometry (DEXA) at femoral neck and lumbar spine (L2-4) and compared with local reference data. RESULTS: For women (n = 9) at L2-4 the mean Z score was -1.21 (95% CI -1.69, -0.73), and at femoral neck -0.57 (95% CI -1.15, 0.00). For men (n = 5) at L2-4, the mean Z score was 1.32 (95% CI -0.86, 3.50) and at femoral neck 0.62 (95% CI -0.18, 1.42). For all patients, there was no significant correlation between mean plasma cortisol and Z scores at L2-4 and femoral neck, r = -0.003 and -0.095 respectively; and between duration of Addison's disease and mean Z scores at L2-4 and femoral neck r = -0.043 and 0.143 respectively. CONCLUSIONS: Women with Addison's disease therefore have a greater than expected reduction in BMD. We postulate that this may be related to loss of adrenal androgens.
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Enfermedad de Addison/fisiopatología , Densidad Ósea , Cuello Femoral/fisiopatología , Vértebras Lumbares/fisiopatología , Absorciometría de Fotón , Enfermedad de Addison/sangre , Enfermedad de Addison/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Hidrocortisona/sangre , Hidrocortisona/uso terapéutico , Masculino , Persona de Mediana Edad , Valores de Referencia , Factores Sexuales , Enfermedades de la Columna Vertebral/fisiopatologíaRESUMEN
AIMS: Studies of the effect of thyroxine therapy on skeletal integrity have given conflicting results; the reductions in bone mass reported by some have prompted recommendations that the prescribed replacement doses of thyroxine should be reduced. We have examined bone mineral density in a group of patients with differentiated thyroid carcinoma receiving high doses of thyroxine to suppress thyroid stimulating hormone (TSH). METHODS: The 44 patients (6 male, 38 female) had a median age of 49 years (range 27-75) with median duration of thyroxine therapy of 9.0 years (range 3 to 42) and mean dose of thyroxine 0.167 mg/day (range 0.125-0.3). TSH levels were chronically suppressed in 39 subjects. Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DEXA) in all subjects at the femoral neck and lumbar spine and compared with previously established local reference ranges. RESULTS: There was no reduction in bone mineral density in the thyroxine treated group compared with the local reference population at both lumbar spine and femoral neck, and no correlation with duration of therapy. CONCLUSIONS: These negative findings, that thyroxine in suppressive doses does not significantly reduce bone mineral density in New Zealand patients suggest that thyroxine therapy alone is not a major risk factor for the development of osteoporosis.
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Adenocarcinoma Folicular/tratamiento farmacológico , Densidad Ósea/efectos de los fármacos , Carcinoma Papilar/tratamiento farmacológico , Osteoporosis/inducido químicamente , Osteoporosis/epidemiología , Neoplasias de la Tiroides/tratamiento farmacológico , Tiroxina/efectos adversos , Absorciometría de Fotón , Adenocarcinoma Folicular/sangre , Adenocarcinoma Folicular/cirugía , Adulto , Factores de Edad , Anciano , Carcinoma Papilar/sangre , Carcinoma Papilar/cirugía , Estudios de Casos y Controles , Femenino , Cuello Femoral/diagnóstico por imagen , Humanos , Vértebras Lumbares/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Osteoporosis/diagnóstico por imagen , Cintigrafía , Valores de Referencia , Factores de Riesgo , Neoplasias de la Tiroides/sangre , Neoplasias de la Tiroides/cirugía , Tiroidectomía , Tirotropina/sangre , Tiroxina/administración & dosificaciónRESUMEN
BACKGROUND: Bone mineral density (BMD) can predict fracture, however, the common use of historical risk factors to predict low BMD is unproven. AIMS: To identify significant historical risk factors for osteopenia. To establish predicting equations for BMD and test their ability to identify those who should be referred for BMD scanning. METHODS: Three hundred and twenty female and 131 male volunteers underwent questionnaire assessment of risk factors and BMD by dual photon absorptiometer at hip and spine. Significant risk factors (P < 0.05) were used to construct a linear regression model to predict BMD. This was cross validated on a second sample of 107 females and 131 males selected from the electoral roll analysing the ability to detect those subjects with BMD in the lower third of the age matched normal range. RESULTS: In women lower BMD at the spine was associated with increased age, decreased weight, smoking, and delayed menarche. Lower femoral BMD was associated with increased age, decreased weight, family history, inactivity, and smoking. In men lower BMD at the lumbar spine was associated with lower weight, and inactivity. Lower BMD at the femur was associated with increased age, decreased weight, family history, and low calcium intake. When cross validated on the second sample, the models produced sensitivity of 86-89% and sensitivity of 25-46%. Referring those with these risk factors could save 10-23% on scanning. Measuring BMD at the site in question remains the only accurate way of assessing an individual's risk of osteopenia.
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Densidad Ósea , Osteoporosis/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Modelos Lineales , Masculino , Persona de Mediana Edad , Análisis Multivariante , Osteoporosis/etnología , Osteoporosis/etiología , Factores de Riesgo , Sensibilidad y Especificidad , Población BlancaRESUMEN
AIM: To determine the effect of screening a normal population for low bone density on lifestyle, subsequent bone density and fracture risk. METHOD: A cross sectional study of 726 subjects screened for low bone density identified 60 with bone density greater than one standard deviation below an age and sex matched mean. Those who accepted further assessment were followed clinically and with repeat bone densitometry for up to four years. Those declining assessment were contacted four years later and questioned about lifestyle changes and fractures. They were offered repeat bone densitometry. RESULTS: Twenty five subjects accepted intervention and were advised on lifestyle modification and treated with calcium supplements (18) calcitriol (5) or oestrogen (1). 22 of the 35 subjects who initially declined intervention volunteered to have their bone density repeated. Bone density increased in the group accepting intervention compared to the 22 subjects in the group who initially declined assessment (p < 0.05). Several laboratory investigations had a low yield. Lifestyle modification in the group declining assessment did not significantly affect subsequent bone density. Fractures occurred infrequently in both groups. CONCLUSION: After screening the normal population for low bone density, significant improvements in bone density can be achieved in patients accepting further intervention.
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Densidad Ósea , Estado de Salud , Adulto , Anciano , Anciano de 80 o más Años , Enfermedades Óseas Metabólicas/etiología , Calcio de la Dieta/administración & dosificación , Estudios de Cohortes , Estudios Transversales , Ejercicio Físico , Femenino , Estudios de Seguimiento , Fracturas Óseas/etiología , Humanos , Estilo de Vida , Masculino , Persona de Mediana Edad , Osteoporosis/etiología , Factores de RiesgoRESUMEN
AIM: To assess the importance of bone density and other risk factors in elderly subjects with hip fractures. METHOD: Thirty-six subjects with femoral neck fracture were compared with 72 community controls in this case control study. Variables compared included: history of falls, previous fracture, body mass index, hand grip strength, blood pressure, medication use, cigarette smoking, alcohol intake, visual acuity, age at menopause, mental status quotient, mobility index and mid thigh circumference. Bone mineral density was measured at the hip (DPA absorptiometer) in the 36 subjects with hip fracture and 36 community controls. RESULTS: Fracture patients had significantly (p < 0.01) reduced bone mineral density at femoral neck (0.64 vs 0.74 g/cm2) and trochanteric regions (0.55 vs 0.66 g/cm2). They also had significantly (p < 0.05) lower body mass index, weaker hand grip strength, smaller mid thigh circumference, reduced mobility and more previous fractures. After controlling for age and sex stepwise logistic regression identified handgrip strength, mobility status and falls in that ranking as risk factors for fracture. Bone mineral density was correlated with mobility status and grip strength. CONCLUSION: Patients with hip fracture have lower bone mineral density than controls. Mobility, grip strength and muscle bulk appear to be important in fracture aetiology and could operate either through bone density or risk of falling.
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Densidad Ósea , Fracturas del Cuello Femoral/epidemiología , Accidentes por Caídas , Actividades Cotidianas , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Femenino , Fracturas del Cuello Femoral/sangre , Fracturas del Cuello Femoral/fisiopatología , Humanos , Masculino , Factores de RiesgoRESUMEN
Eighteen healthy people over 65 years of age were studied to compare the 99mTC-diethylenetriamine pentaacetic acid (DTPA) clearance, the measured 24-hour creatinine clearance and the assessed creatinine clearance using the Cockcroft and Gault (C-G) formula to measure their glomerular filtration rate. Significant correlations were found between the isotopic method and the measured creatinine clearance (r = 0.71; p less than 0.001); the measured creatinine clearance and the C-G formula (r = 0.81; p less than 0.001), and the isotopic method and the C-G formula (r = 0.70; p less than 0.001). The C-G formula correlated better with both the 99mTc-DTPA clearance and the measured creatinine clearance when the female correction factor was used. This study has shown that in healthy, elderly people, the C-G formula for assessing the creatinine clearance correlated extremely well with the standard clinical tests for measuring the glomerular filtration rate. Whilst the formula has clinical value and allows rapid and accurate assessment of renal function in the elderly, the clinician must be aware that the formula relatively underestimates the true renal clearance.