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Biocrusts are key ecosystem engineers that are being destroyed due to anthropogenic disturbances such as trampling, agriculture and mining. In hyper-arid regions of the Negev Desert, phosphate has been mined for over six decades, altering the natural landscape over large spatial scales. In recent years, restoration-oriented practices were mandated in mining sites, however, the impact of such practices on the ecosystem, particularly the biocrust layer, has not been tested. Here, we evaluated post-mining biocrust bacterial communities and compared them to undisturbed (reference) biocrusts. We collected samples from four mining sites (each restored at a different year) and their corresponding reference sites. We hypothesized that post-mining bacterial communities would differ significantly from reference communities, given the slow regeneration of the biocrust. We also hypothesized that bacterial communities would vary among post-mining plots based on their restoration age. To test these hypotheses, we assessed the abundance and diversity of bacterial communities by sequencing the 16S rDNA and their photosynthetic potential by quantifying the abundance of cyanobacteria and chlorophyll a. The bacterial diversity was lower, and community composition differed significantly between post-mining and reference biocrusts. In addition, cyanobacteria abundances and chlorophyll a content were lower in post-mining biocrusts, indicating lower photosynthetic potential. However, no significant changes in bacterial communities were detected, regardless of the restoration age. We suggest that the practices implemented in the Negev mines may not support the recovery of the biocrust bacterial communities, particularly the cyanobacteria. Thus, active restoration measures are needed to accelerate the regeneration time of biocrusts at the hyper-arid Negev mines.
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Cianobacterias , Ecosistema , Clorofila A , Cianobacterias/genética , Clima Desértico , Minería , Fosfatos , Suelo , Microbiología del SueloRESUMEN
Grazing plays an important role in shaping ecological communities in human-related ecosystems. Although myriad studies have explored the joint effect of grazing and climate on plant communities, this interactive effect has rarely been studied in animals. We hypothesized that the effect of grazing on the reptile community varies along a climatic gradient in relation to the effect of grazing on habitat characteristics, and that grazing differentially affects reptiles of different biogeographic regions. We tested our hypotheses by collecting data on environmental characteristics and by trapping reptiles in four heterogeneous landscapes experiencing differing grazing intensities and distributed along a sharp climatic gradient. We found that while reptile diversity increased with grazing intensity at the mesic end of the gradient, it decreased with grazing intensity at the arid end. Moreover, the proportion of reptile species of differing biogeographic origins varied with the interactive effect of climate and grazing. The representation of species originating in arid biogeographic zones was highest at the arid end of the climatic gradient, and representation increased with grazing intensity within this area. Regardless of the climatic context, increased grazing pressure results in a reduction in vegetation cover and thus in changes in habitat characteristics. By reducing vegetation cover, grazing increased habitat heterogeneity in the dense mesic sites and decreased habitat heterogeneity in the arid sites. Thus, our results suggest that the same direction of habitat alteration caused by grazing may have opposite effects on biodiversity and community composition in different climatic contexts.
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Biodiversidad , Clima , Ecosistema , Herbivoria , Ganado , Plantas , Reptiles , Agricultura , Alimentación Animal , Animales , Dieta , Humanos , Dinámica Poblacional , AguaRESUMEN
BACKGROUND: Despite the overall success of total knee arthroplasty (TKA), a relatively large proportion of patients remain dissatisfied with the outcome. We hypothesized that patients with a lower threshold for pain were more likely to have worse outcomes after TKA. METHODS: Forty-eight consecutive patients with primary knee osteoarthritis graded a standardized painful stimulus caused by inflating a sphygmomanometer placed on the forearm, on a visual analog scale (VAS) scale before their TKA. We compared the VAS scores to patients' Knee Society scores and Knee Society function scores 2 years after TKA. RESULTS: Patients with a severe VAS score (>74 mm) had significantly worse Knee Society scores compared to patients with mild (0-44 mm) and moderate (45-74 mm) VAS scores (55 ± 20.5 vs 81.5 ± 11.1 and 84.8 ± 13, respectively, P = .04) and worse Knee Society Function scores (34 ± 20.7 vs 75.2 ± 17.3 and 77 ± 17.4, respectively, P = .027) at 2 years after TKA. CONCLUSIONS: Patients with a lower threshold for pain, as determined by a standardized painful stimulus, are more likely to have lower Knee Society pain and function scores after TKA.
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Artroplastia de Reemplazo de Rodilla/efectos adversos , Dimensión del Dolor/métodos , Dolor Postoperatorio/etiología , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Articulación de la Rodilla/cirugía , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/cirugía , Dolor/etiología , Dimensión del Dolor/instrumentación , Estudios Prospectivos , Esfigmomanometros , Resultado del TratamientoRESUMEN
Gaucher disease (GD) is one of the most common lysosomal storage disorders. Bone complications are the most critical irreversible consequence of GD. Osteonecrosis (ON) of the femoral head inevitably leads to osteoarthritis and may be managed by hip arthroplasty. The introduction and worldwide use of therapeutic agents (specifically enzyme replacement therapies (ERT)) lowered the prevalence of osteonecrosis events per patient. We present the cases of two female patients who sustained simultaneous bilateral femoral head osteonecrosis after receiving ERT for long periods while exposed to concomitant risk factors related to femoral head ON. Both patients suffered severe pain and deterioration of their daily activity capabilities, and thus, were offered bilateral hip arthroplasty. Surgery was performed in both hip joints during the same procedure. The current report highlights several key aspects of femoral head ON in young patients with GD.
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Habitat loss reduces species diversity, but the effect of habitat fragmentation on number of species is less clear because fragmentation generally accompanies loss of habitat. We compared four methods that aim to decouple the effects of fragmentation from the effects of habitat loss. Two methods are based on species-area relations, one on Fisher's alpha index of diversity, and one on plots of cumulative number of species detected against cumulative area sampled. We used these methods to analyze the species diversity of spiders in 2, 3.2 × 4 km agricultural landscapes in Southern Judea Lowlands, Israel. Spider diversity increased as fragmentation increased with all four methods, probably not because of the additive within-patch processes, such as edge effect and heterogeneity. The positive relation between fragmentation and species diversity might reflect that most species can disperse through the fields during the wheat-growing season. We suggest that if a given area was designated for the conservation of spiders in Southern Judea Lowlands, Israel, a set of several small patches may maximize species diversity over time.
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Biodiversidad , Conservación de los Recursos Naturales , Ecosistema , Arañas/fisiología , Agricultura , Animales , Densidad de Población , Dinámica PoblacionalRESUMEN
The aim of this study was to assess the safety and functional outcomes of excessive sagittal alignment in the unrestricted kinematic alignment technique for total knee arthroplasty (TKA). A retrospective, single-center study was conducted between 2018 and 2020, including patients undergoing primary TKA with a minimum 2-year follow-up. EOS imaging conducted before and after surgery was reviewed for overall alignment, and a number of measurements were taken, including sagittal tibial slope and other tibia and femur component positioning. Patients were interviewed and asked to fill out several questionnaires including a visual analog scale, the Oxford Knee Score, and the Knee Injury and Osteoarthritis Outcome Score. Overall, 225 patients (66.7%) had a sagittal tibial slope angle above 5° (excessive) and 112 (33.3%) patients had an angle under 5° (moderate). A significant improvement in pain and function scores was observed in both groups following the surgery (p < 0.001). There were no significant differences between the moderate and excessive groups in the average VAS, OKS or the various subtypes of the KOOS score. However, there was a slight but significant difference in the number of patients achieving MCID in KOOS symptoms. There were no cases of early failure or loosening. Unrestricted KA and the excessive sagittal alignment of the tibial component seem to be reliable and safe in terms of restoring daily function and alleviating pain after a minimum of 2 years following the surgery.
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Kinematic alignment (KA) total knee arthroplasty (TKA) has gained much attention in recent years. However, debate remains on whether restrictions should be made on the tibia cut. The purpose of this study was to assess the safety and functional outcomes of excessive varus cuts. A single-center, retrospective analysis of consecutive patients undergoing TKA between 2018 and 2020 who had a minimum 2-year follow-up was conducted. EOS™ imaging conducted before and after surgery was analyzed for overall alignment, as well as for tibia and femur component positioning on the coronal planes. Patients were interviewed and asked to fill several questionnaires, including the visual analog score, Oxford knee score, and knee injury and osteoarthritis outcome score. Overall, 243 patients (71.9%) had a coronal tibial plate angle under 5° (moderate) and 95 patients (28.1%) had an angle above 5° (excessive). There were no significant differences between the moderate and excessive groups in patient-reported outcomes, nor were there differences in the number of patients achieving the minimal clinical difference. There were no cases of catastrophic failure or loosening. Unrestricted KA and excessive varus of the tibial component appears to be safe and efficient in relieving pain and restoring function for a minimum of 2 years following surgery.
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Kinematic alignment (KA) total knee arthroplasty (TKA) has gained popularity in the past decade, but outcomes of KA-TKA in the valgus knee have never been specifically evaluated. In this retrospective single institution study, we analyzed patient reported outcomes and radiographic measurements at minimum 2 years following KA-TKA for valgus knees (n = 51) and compared the results to KA-TKA performed for non-valgus knees (n = 275). The same approach, technique, and implants were used in both groups without the need to release soft tissues or use constrained implants. Surgery duration was similar between groups (p = 0.353). Lateral distal femoral angle was lower in the valgus group postoperatively (p = 0.036). In both groups significant improvement was seen in relieving pain and improving function, while average scores were superior in the non-valgus group for visual analog score (p = 0.005), oxford knee score (p = 0.013), and knee injury and osteoarthritis outcome score (p = 0.009). However, these differences did not translate to statistically significant differences in minimal clinical important difference achievement rates. In conclusion, KA-TKA is efficient in relieving pain and improving function, as reported in subjective questionnaires, and holds advantage in patients with valgus alignment by avoiding soft tissue releases and use of constrained implants. Future studies should examine whether bone loss occurs in the lateral distal femur.
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BACKGROUND: Patients with osteoarthritis (OA) take a variety of health supplements in an attempt to reduce pain and improve function. The aim of this study was to determine the efficacy of methylsulfonylmethane (MSM) in treating patients with knee OA. METHODS: This study was a prospective, randomized, double-blind, controlled clinical trial. Forty nine men and women 45-90 (mean 68 ± SD 7.3) years of age with knee OA according to the American College of Rheumatology clinical criteria for OA of the knee and with radiographic confirmed knee OA were enrolled in the study and randomly assigned into 2 groups: One received MSM in doses of 1.125 grams 3 times daily for 12 weeks and the other received a placebo in the same dosing frequency. The primary outcomes were the WOMAC Osteoarthritis Index for pain, stiffness and physical function, the Aggregated Locomotor Function (ALF) test that evaluates each patient's physical function, the SF-36 quality of life health survey and the visual-analogue-scale (VAS) for pain. The secondary outcomes were Knee Society Clinical Rating System for Knee Score (KSKS) and Function Score (KSFS). Patients were assessed at baseline, 6 weeks and 12 weeks. All continuous variables were tested by the Kolmogorov-Smirnov test for Normal distribution. Changes within the groups and differences between the groups were calculated by repeated measures of analysis (ANOVA) with one nested variable. RESULTS: There were significant differences between treatment groups over time in WOMAC physical function (14.6 mm [CI: 4.3, 25.0]; p = 0.04) and in WOMAC total score (15.0 mm [CI: 5.1, 24.9]; p = 0.03). Treatment groups did not differ significantly in WOMAC pain (12.4 mm [CI: 0.0, 24.8]); p = 0.08) or WOMAC stiffness (27.2 mm [CI: 8.2, 46.2]; p = 0.08). There was a non-significant difference in SF-36 total score between treatment groups (11.6 [CI: 1.0, 22.1]; p = 0.54). A significant difference was found between groups in VAS for pain (0.7 s [CI: -0.9, 2.4]; p = 0.05). Secondary outcomes showed non-significant differences between the two groups. CONCLUSIONS: Patients with OA of the knee taking MSM for 12 weeks showed an improvement in pain and physical function. These improvements, however, are small and it is yet to be determined if they are of clinical significance. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01188213.
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Antiinflamatorios/uso terapéutico , Dimetilsulfóxido/uso terapéutico , Articulación de la Rodilla/efectos de los fármacos , Locomoción/efectos de los fármacos , Limitación de la Movilidad , Osteoartritis de la Rodilla/tratamiento farmacológico , Dolor/tratamiento farmacológico , Sulfonas/uso terapéutico , Actividades Cotidianas , Anciano , Anciano de 80 o más Años , Análisis de Varianza , Antiinflamatorios/farmacología , Suplementos Dietéticos , Dimetilsulfóxido/farmacología , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/complicaciones , Dolor/etiología , Dimensión del Dolor , Estudios Prospectivos , Calidad de Vida , Sulfonas/farmacologíaRESUMEN
BACKGROUND: This prospective study aimed to assess the reliability and validity of the Hebrew version of the forgotten joint score-12 in patients undergoing total knee arthroplasty, because it is going to be used in the Hebrew-speaking populations in Israel. METHODS: The English version of forgotten joint score-12 was translated into Hebrew version by using the standard procedures and in collaboration with its authors. The consecutive patients who had undergone total knee arthroplasty in a single hospital were asked to fill out the Hebrew version of forgotten joint score-12, Oxford knee score, Short Form 12, and visual analog scale. A random subgroup of 60 patients were then asked to fill out a second Hebrew version of forgotten joint score-12 at a minimum of 2-week interval. The reliability was assessed in terms of internal consistency, test-retest reliability and split-half reliability. The validity was measured in terms of the outcomes as mentioned above. RESULTS: A total of 102 patients participated in the study. The Hebrew version of forgotten joint score-12 showed high reliability. The internal consistency was excellent (Cronbachs' α = 0.943) and test-retest reliability was high (Intraclass correlation = 0.97). The forgotten joint scores were correlated with the Oxford knee score, Short Form 12, and visual analog scale (r = 0.86, r = 0.72, and r=-0.8, respectively), indicating a high validity. CONCLUSIONS: The Hebrew version of forgotten joint score-12 has excellent reliability, excellent test-retest reliability and good validity. It can be safely used for assessing outcomes of TKA.
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BACKGROUND: This study examined the effect of treatment with a novel biomechanical device on the level of pain and function in patients with knee OA. METHODS: Patients with bilateral knee OA were enrolled to active and control groups. Patients were evaluated at baseline, at 4 weeks and at the 8-week endpoint. A novel biomechanical device was individually calibrated to patients from the active group. Patients from the control group received an identical foot-worn platform without the biomechanical elements. Primary outcomes were the WOMAC Index and ALF assessments. RESULTS: There were no baseline differences between the groups. At 8 weeks, the active group showed a mean improvement of 64.8% on the WOMAC pain scale, a mean improvement of 62.7% on the WOMAC function scale, and a mean improvement of 31.4% on the ALF scale. The control group demonstrated no improvement in the above parameters. Significant differences were found between the active and control groups in all the parameters of assessment. CONCLUSIONS: The biomechanical device and treatment methodology is effective in significantly reducing pain and improving function in knee OA patients.The study is registered at clinicaltrials.gov, identifier NCT00457132, http://www.clinicaltrials.gov/ct/show/NCT00457132?order=1.
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Artralgia/terapia , Pie/fisiología , Aparatos Ortopédicos/estadística & datos numéricos , Osteoartritis de la Rodilla/terapia , Diseño de Prótesis/métodos , Actividades Cotidianas , Anciano , Artralgia/fisiopatología , Artralgia/prevención & control , Fenómenos Biomecánicos/fisiología , Femenino , Pie/anatomía & histología , Marcha/fisiología , Humanos , Articulación de la Rodilla/patología , Articulación de la Rodilla/fisiopatología , Masculino , Persona de Mediana Edad , Limitación de la Movilidad , Aparatos Ortopédicos/tendencias , Osteoartritis de la Rodilla/fisiopatología , Osteoartritis de la Rodilla/prevención & control , Dimensión del Dolor/métodos , Estudios Prospectivos , Rango del Movimiento Articular/fisiología , Resultado del Tratamiento , Caminata/fisiología , Soporte de Peso/fisiologíaRESUMEN
This study examined the prevalence of anterior knee pain (AKP) and pes planus (PP) in Israeli defense force recruits and assessed the relationship between these conditions. We examined the medical records of 97,279 recruits--18,338 females and 78,941 males. The prevalence of AKP was 4.15%. It was lower in females (2.39%) than in males (4.56%). The prevalence of flexible and rigid PP were 15.30% and 0.83%, respectively. The prevalence of both conditions was lower in females (11.31% and 0.34%) than in males (16.23% and 0.94%). AKP was more prevalent in individuals with flexible PP (4.50%) than with normal feet (4.06%) and more prevalent in individuals with rigid PP (6.93%) than in individuals with flexible PP. Despite current opinion, AKP is more common in males than in females. The role of orthotics in individuals with AKP and PP should be more thoroughly investigated.
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Artralgia/epidemiología , Pie Plano/epidemiología , Personal Militar , Articulación Patelofemoral , Adolescente , Adulto , Comorbilidad , Femenino , Humanos , Israel/epidemiología , Masculino , PrevalenciaRESUMEN
CASE: A 33-year-old man presented with acute abdominal and left hip pain after being struck by a motor vehicle. Radiographs revealed a comminuted left subtrochanteric femoral fracture. Computed tomography demonstrated a large pelvic hematoma and a radiopaque mass in the abdomen. Laparoscopy revealed the mass to be a large bone fragment lying within the greater omentum. The bone fragment, which seemed to be a femoral fracture fragment, was removed, and the fracture was repaired with a short cephalomedullary nail. CONCLUSION: Rarely, subtrochanteric fracture fragments can penetrate the pelvis or abdomen because of high-energy trauma. Recognizing this possibility is important to assure a correct diagnosis and subsequent treatment.
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Dolor Abdominal/etiología , Fracturas Conminutas/complicaciones , Fracturas de Cadera/complicaciones , Dolor Abdominal/diagnóstico por imagen , Adulto , Fracturas Conminutas/diagnóstico por imagen , Fracturas de Cadera/diagnóstico por imagen , Humanos , Masculino , Tomografía Computarizada por Rayos XRESUMEN
INTRODUCTION: Backboards are routinely used to protect the spine of trauma patients during transportation. Nevertheless, little is known about the biomechanical properties of this type of immobilization. OBJECTIVES: To evaluate the mechanical support of the thoracolumbosacral spine provided by a standard backboard in comparison with various rigid immobilization surfaces, by examining their respective surface contact area (SCA). MATERIALS: SCAs comparisons of a standard aluminum backboard, a rigid military stretcher, an aluminum backboard covered by blanket, 3 and 5 cm thickness foam, and a cushioned stretcher were made using 12 volunteers. The evaluation was performed by a computer- mediated system that generated a diagram indicating pressure distribution and SCA score in each volunteer. These data were compared with a medical grade mattress, which served as the control group. RESULTS: The median backboard's SCA was 14.6 +/- 5.5 times smaller than the stretcher's SCA (range 4.6-28, average 15, p < 0.001). Its median SCA was essentially doubled by covering it by a standard military blanket and tripled when covered by 3 cm layer of foam. Using a 5-cm layer of foam increased the backboard's SCA by 11 times. Cushioning the stretcher beneath the lumbar spine and the hamstrings by folded blankets, significantly improved its median SCA (96 +/- 31.1, range 36-125, average 89.7). CONCLUSIONS: The backboard's SCA was significantly inferior to all the other surfaces. Although no dynamic evaluation was performed, these data imply that backboards need to be appropriately cushioned or alternate surfaces should be employed to improve the mechanical support during trauma patient transportation. Level of evidence, Level I.
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Inmovilización/instrumentación , Traumatismos Vertebrales , Transporte de Pacientes/métodos , Fenómenos Biomecánicos , Diseño de Equipo , Femenino , Humanos , Masculino , PresiónRESUMEN
BACKGROUND: Intraarticular injections of the hip have traditionally required sonographic or fluoroscopic guidance assistance. Previous studies report high failure rates with injections based solely on anatomic landmarks. OBJECTIVES: To examine the accuracy of a lateral injection technique in osteoarthritic patients without using image assistance. METHODS: This study was conducted in the operating room in 40 consecutive patients about to undergo total hip arthroplasty. Before sedation, each patient was positioned in a lateral decubitus position. Under sterile conditions, methylene blue dye was injected through an 18G spinal needle that was inserted 1 cm proximal to the midline of the greater trochanter, and directed toward the superolateral aspect of the femoral neck, according to preoperative hip x-rays. Accuracy was assessed intraoperatively by examining the joint and surrounding tissues for the presence of dye. RESULTS: Injections were successful in 6 of the first 10 (60%) patients and in 25 of the remaining 30 (83.3%) patients. Overall, injections were successful in 31 of 40 (77.5%) patients with disseminated dye solely in the intracapsular space. In all 9 unsuccessful injections, the dye was located distal to the joint, along with the more lateral aspect of the femoral neck. CONCLUSION: Accuracy of injections, to the hip joint, based on anatomic landmarks and preoperative x-rays is similar to those documented for knee injections in the literature. When unsuccessful, the injected material was not found close to neurovascular structures. This technique has an acceptable learning curve and can be used safely in a standard office setting.
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Articulación de la Cadera/anatomía & histología , Inyecciones Intraarticulares/métodos , Osteoartritis de la Cadera/tratamiento farmacológico , Competencia Clínica , Estudios de Cohortes , HumanosRESUMEN
Most papers on the physical condition of birds during spring migration focused on food availability preceding migratory take-off. Only a few studies examined the effect of climate conditions at the wintering grounds upon autumn arrival on bird physical condition later on. Here, we hypothesized that environmental conditions upon arrival at the wintering grounds, and not necessarily upon departure, have a crucial carry-over effect on bird spring migration. Using 29,000 observations of the lesser whitethroat, Sylvia curruca, and the eastern Bonelli's warbler, Phylloscopus orientalis, we found temperatures upon arrival at the African wintering grounds to be the only climatic variable correlated with birds' body state upon spring stopover in Israel, six months later. Two different mechanisms could explain these results. One possibility is that high temperatures create favorable conditions for insect activity, which allows rapid recovery from autumn migration and hence successful winter survival and maintenance. Another possible scenario is that harsh conditions, due to the heat and dry environment, cause high mortality, permitting survival of larger individuals which, then, enjoy reduced inter- and intra-specific competition. Whatever the mechanism is, our findings suggest that conditions upon autumn arrival, and not necessarily at the end of winter as traditionally thought, may have a major impact on migrating birds.
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Migración Animal/fisiología , Passeriformes/fisiología , Animales , Ecosistema , Estaciones del Año , TemperaturaRESUMEN
Habitat destruction is the single greatest anthropogenic threat to biodiversity. Decades of research on this issue have led to the accumulation of hundreds of data sets comparing species assemblages in larger, intact, habitats to smaller, more fragmented, habitats. Despite this, little synthesis or consensus has been achieved, primarily because of non-standardized sampling methodology and analyses of notoriously scale-dependent response variables (i.e., species richness). To be able to compare and contrast the results of habitat fragmentation on species' assemblages, it is necessary to have the underlying data on species abundances and sampling intensity, so that standardization can be achieved. To accomplish this, we systematically searched the literature for studies where abundances of species in assemblages (of any taxa) were sampled from many habitat patches that varied in size. From these, we extracted data from several studies, and contacted authors of studies where appropriate data were collected but not published, giving us 117 studies that compared species assemblages among habitat fragments that varied in area. Less than one-half (41) of studies came from tropical forests of Central and South America, but there were many studies from temperate forests and grasslands from all continents except Antarctica. Fifty-four of the studies were on invertebrates (mostly insects), but there were several studies on plants (15), birds (16), mammals (19), and reptiles and amphibians (13). We also collected qualitative information on the length of time since fragmentation. With data on total and relative abundances (and identities) of species, sampling effort, and affiliated meta-data about the study sites, these data can be used to more definitively test hypotheses about the role of habitat fragmentation in altering patterns of biodiversity. There are no copyright restrictions. Please cite this data paper and the associated Dryad data set if the data are used in publications.
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Patterns of genetic differentiation among taxa at early stages of divergence provide an opportunity to make inferences about the history of speciation. Here, we conduct a survey of DNA-sequence polymorphism and divergence at loci on the autosomes, X chromosome, Y chromosome and mitochondrial DNA in samples of Mus domesticus, M. musculus and M. castaneus. We analyzed our data under a divergence with gene flow model and estimate that the effective population size of M. castaneus is 200,000-400,000, of M. domesticus is 100,000-200,000 and of M. musculus is 60,000-120,000. These data also suggest that these species started to diverge approximately 500,000 years ago. Consistent with this recent divergence, we observed considerable variation in the genealogical patterns among loci. For some loci, all alleles within each species formed a monophyletic group, while at other loci, species were intermingled on the phylogeny of alleles. This intermingling probably reflects both incomplete lineage sorting and gene flow after divergence. Likelihood ratio tests rejected a strict allopatric model with no gene flow in comparisons between each pair of species. Gene flow was asymmetric: no gene flow was detected into M. domesticus, while significant gene flow was detected into both M. castaneus and M. musculus. Finally, most of the gene flow occurred at autosomal loci, resulting in a significantly higher ratio of fixed differences to polymorphisms at the X and Y chromosomes relative to autosomes in some comparisons, or just the X chromosome in others, emphasizing the important role of the sex chromosomes in general and the X chromosome in particular in speciation.
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Genes Mitocondriales , Genes Ligados a X , Genes Ligados a Y , Especiación Genética , Ratones/genética , Alelos , Animales , ADN Mitocondrial/genética , Evolución Molecular , Flujo Génico , Genética de Población , Funciones de Verosimilitud , Ratones/clasificación , Mitocondrias/genética , Modelos Genéticos , Filogenia , Polimorfismo Genético , Análisis de Secuencia de ADN , Especificidad de la Especie , Cromosoma X/genética , Cromosoma Y/genéticaRESUMEN
The size of the regional species pool may influence local patterns of diversity. However, it is unclear whether certain spatial scales are less sensitive to regional influences than others. Additive partitioning was used to separate coral-dwelling fish diversity to its alpha and beta components, at multiple scales, in several regions across the Indo-Pacific. We then examined how the relative contribution of these components changes with increased regional diversity. By employing specific random-placement null models, we overcome methodological problems with local-regional regressions. We show that, although alpha and beta diversities within each region are consistently different from random-placement null models, the increase in beta diversities among regions was similar to that predicted once heterogeneity in coral habitat was accounted for. In contrast, alpha diversity within single coral heads was limited and increased less than predicted by the null models. This was correlated with increased intraspecific aggregation in more diverse regions and is consistent with ecological limitations on the number of coexisting species at the local scale. These results suggest that, apart from very small spatial scales, variation in the partitioning of fish diversity along regional species richness gradients is driven overwhelmingly by the corresponding gradients in coral assemblage structure.