1,459 research outputs found
Preventing tropical mining disasters
Mining for fossil fuels and minerals is penetrating into many of the world's most remote and biologically important tropical forests. In the Amazon, there are some 53,000 active mining leases (1), and hundreds of billions of dollars in new mines are planned across the Congo basin (2). But are extractive industries in the tropics investing sufficiently to prevent environmental disasters
The ecological response of lianas to long-term tropical forest fragmentation
Understanding forest dynamics within remnant fragments of tropical forest is a vital priority if we are to manage them effectively for biodiversity conservation. Lianas (woody vines) are well known to interact antagonistically with trees, and if they flourish in older forest fragments they may promote detrimental ecological impacts and fragment degradation. We assessed liana assemblages in remnant rainforests of the Atherton Tablelands of north Queensland, Australia, which were fragmented up to a century ago. We surveyed 10 remnant forest patches ranging from 17 to 920 ha in area, and five large intact-forest control sites. A total of 75 sampling plots (20 × 20 m) were established, with five plots per site. All tree and liana individuals ≥10 cm and ≥1 cm dbh (diameter at breast height), respectively, were enumerated, measured and permanently tagged. A total of 5130 tree and liana stems were recorded. We evaluated the relationship of fragment area and environmental and disturbance parameters to liana abundance and biomass. It is apparent that lianas often increase dramatically in abundance in historically fragmented forests, especially those with large amounts of forest edge or recurring canopy disturbance. Where lianas are hyper-abundant they alter tree-community composition and reduce forest carbon storage. If lianas benefit markedly from rising atmospheric CO2 levels or other global-change phenomena, then they will become even more dominant in fragmented forests of the future
Book Reviews
CARDOZO AND FRONTIERS OF LEGAL THINKING. By B. H. Levy. Cleveland: Case Western Reserve University Press, 1969. Pp. xi, 365. 9.95.
KEEPING THE PEACE. By Herbert Jenkins. New York: Harper & Row, 1970. Pp. 203. 5.95.
ATTORNEYS\u27 GUIDE TO SELECTIVE SERVICE AND MILITARY CASE LAW. By Curry First. Philadelphia: Central Committee for Conscientious Objectors, 1969. Pp. 187. 1.75.
TRUTH IN REAL ESTATE LENDING. By Joseph L. Abraham. Chicago, Ill., Commerce Clearing House, 1970. Pp. xii, 299. $12.50
Diagnosis of lipomatous hypertrophy of the atrial septum by two-dimensional echocardiography
Originally described in 1964, lipomatous hypertrophy of the atrial septum currently remains a diagnosis established primarily at autopsy. Clinical interest in this disorder has centered on the reported association with supraventricular arrhythmias and sudden death. Because two-dimensional echocardiography allows detailed assessment of atrial septal configuration, we reviewed two-dimensional echocardiographic reports obtained over a 1 year period and identified 17 patients who had features consistent with lipomatous hypertrophy of the atrial septum. Nine were men and the average age was 70 years. Autopsy confirmation of the echographic findings was possible in one patient. In nine patients, ideal body weight was exceeded by 10% or more. The atrial septum viewed from the subcostal transducer position showed a distinctive echo-dense globular thickening sparing the valve of the fossa ovalis. The resultant tomographic image of the atrial septum had a characteristic dumbbell appearance. The mean thickness of the atrial septum was 21 mm (range 15 to 29). Seven patients had supraventricular arrhythmias, and eight had P wave abnormalities.The two-dimensional echocardiographic features described are distinctive and suggest that this technique is the procedure of choice not only for establishing the diagnosis of lipomatous hypertrophy of the atrial septum but also for providing a means for prospective follow-up of patients with this little known entity
Modeling the ecology and evolution of biodiversity: Biogeographical cradles, museums, and graves
Individual processes shaping geographical patterns of biodiversity are increasingly understood, but their complex interactions on broad spatial and temporal scales remain beyond the reach of analytical models and traditional experiments. To meet this challenge, we built a spatially explicit, mechanistic simulation model implementing adaptation, range shifts, fragmentation, speciation, dispersal, competition, and extinction, driven by modeled climates of the past 800,000 years in South America. Experimental topographic smoothing confirmed the impact of climate heterogeneity on diversification. The simulations identified regions and episodes of speciation (cradles), persistence (museums), and extinction (graves). Although the simulations had no target pattern and were not parameterized with empirical data, emerging richness maps closely resembled contemporary maps for major taxa, confirming powerful roles for evolution and diversification driven by topography and climate
Effects of oil palm and human presence on activity patterns of terrestrial mammals in the Colombian Llanos
The ability of animals to adjust their behaviour can influence how they respond to environmental changes and human presence. We quantified activity patterns of terrestrial mammals in oil palm plantations and native riparian forest in Colombia to determine if species exhibited behavioural changes depending on the type of habitat and the presence of humans. Despite the large sampling effort (12,403 camera-days), we were only able to examine the activity patterns of ten species in riparian forests and seven species in oil palm plantations, with four species (capybara, giant anteater, lesser anteater and common opossum) being represented by enough records (i.e. n > 20) in both oil palm and forest to allow robust comparisons. Only capybaras showed an apparent change in activity patterns between oil palm plantations and riparian forests, shifting from being crepuscular in forest to predominantly nocturnal inside oil palm plantations. Further, capybaras, giant anteaters and white-tailed deer appeared to modify their activities to avoid human presence inside oil palm plantations by increasing nocturnality (temporal overlap Δ ^ ranged from 0.13 to 0.36), whereas jaguarundi had high overlap with human activities [Δ ^ =0.85 (0.61–0.90)]. Species pair-wise analysis within oil palm revealed evidence for temporal segregation between species occupying the same trophic position (e.g. foxes and jaguarundi), whereas some predators and their prey (e.g. ocelots and armadillos) had high overlaps in temporal activity patterns as might be expected. Our findings shed light on the potential behavioural adaptation of mammals to anthropogenic landscapes, a feature not captured in traditional studies that focus on measures such as species richness or abundance
CD4 intragenic SNPs associate with HIV-2 plasma viral load and CD4 count in a community-based study from Guinea-Bissau, West Africa.
OBJECTIVES: The human genetics of HIV-2 infection and disease progression is understudied. Therefore, we studied the effect of variation in 2 genes that encode products critical to HIV pathogenesis and disease progression: CD4 and CD209. DESIGN: This cross-sectional study consisted of 143 HIV-2, 30 HIV-1 + HIV-2 and 29 HIV-1-infected subjects and 194 uninfected controls recruited from rural Guinea-Bissau. METHODS: We genotyped 14 CD4 and 4 CD209 single nucleotide polymorphisms (SNPs) that were tested for association with HIV infection, HIV-2 plasma viral load (high vs. low), and CD4 T-cell count (high vs. low). RESULTS: The most significant association was between a CD4 haplotype rs11575097-rs10849523 and high viral load [odds ratio (OR): = 2.37, 95% confidence interval (CI): 1.35 to 4.19, P = 0.001, corrected for multiple testing], suggesting increased genetic susceptibility to HIV-2 disease progression for individuals carrying the high-risk haplotype. Significant associations were also observed at a CD4 SNP (rs2255301) with HIV-2 infection (OR: = 2.36, 95% CI: 1.19 to 4.65, P = 0.01) and any HIV infection (OR: = 2.50, 95% CI: 1.34 to 4.69, P = 0.004). CONCLUSIONS: Our results support a role of CD4 polymorphisms in HIV-2 infection, in agreement with recent data showing that CD4 gene variants increase risk to HIV-1 in Kenyan female sex workers. These findings indicate at least some commonality in HIV-1 and HIV-2 susceptibility
Prospects for the Study of Evolution in the Deep Biosphere
Since the days of Darwin, scientists have used the framework of the theory of evolution to explore the interconnectedness of life on Earth and adaptation of organisms to the ever-changing environment. The advent of molecular biology has advanced and accelerated the study of evolution by allowing direct examination of the genetic material that ultimately determines the phenotypes upon which selection acts. The study of evolution has been furthered through examination of microbial evolution, with large population numbers, short generation times, and easily extractable DNA. Such work has spawned the study of microbial biogeography, with the realization that concepts developed in population genetics may be applicable to microbial genomes (Martiny et al., 2006; Manhes and Velicer, 2011). Microbial biogeography and adaptation has been examined in many different environments. Here we argue that the deep biosphere is a unique environment for the study of evolution and list specific factors that can be considered and where the studies may be performed. This publication is the result of the NSF-funded Center for Dark Energy Biosphere Investigations (C-DEBI) theme team on Evolution (www.darkenergybiosphere.org)
BREEDING BEHAVIOR OF THE GRAY-BREASTED FLYCATCHER (LATHROTRICCUS GRISEIPECTUS) IN SOUTHWESTERN ECUADOR
Abstract ∙ Little is known about the nesting behavior of the Gray-breasted Flycatcher (Lathrotriccus griseipectus), a species listed as Vulnerable by the International Union for Conservation of Nature. In order to add fundamental information on the life history of this species, we recorded parental behavior at a nest in February–March 2010 in the Jorupe Reserve in southwestern Ecuador. Recordings were made on a tripod-mounted video camera and took place during part of the incubation and nestling stages. Both adults provisioned nestlings. We recorded 7.1 feeds per nestling-hour, with the highest average provisioning rates occurring from 12:00–13:00 h. Nestlings produced an average of 0.8 fecal sacs per nestling-hour. Nestlings fledged in quick succession shortly before 12:00 h on nestling-day 14.Resumen ∙ El cuidado parental del Mosquero Pechigrís (Lathrotriccus griseipectus) en el suroeste del Ecuador La biología reproductiva del Mosquero Pechigrís (Lathrotriccus griseipectus), una especie catalogada como “Vulnerable” por la Unión Internacional para la Conservación de la Naturaleza, es poco conocida. Con el fin de añadir datos básicos sobre la historia de vida del Mosquero Pechigrís, utilizamos una cámara de video para realizar observaciones de un nido ubicado en la Reserva Jorupe en el suroeste de Ecuador, entre febrero y marzo de 2010. Las grabaciones tuvieron lugar durante parte de las etapas de incubación y polluelo. Ambos adultos aprovisionaron polluelos. Registramos 7.1 alimentaciones de polluelo por hora, siendo las tasas de aprovisionamiento más altas de 12:00–13:00 h. Los polluelos produjeron un promedio de 0.8 sacos fecales por hora y polluelo. Los polluelos emplumaron en rápida sucesión poco antes del mediodía 14 días luego de la eclosión
Structural recovery of logged forests in the Solomon Islands: implications for conservation and management
Much of the lowland tropical forests in the Solomon Islands have been heavily logged. However, little is known about the recovery status of these forests. We examined factors that influenced the recovery of forest structural attributes within 50 years after selective logging on Kolombangara Island in the western Solomon Islands. Twelve study sites—six logged and six unlogged—were identified across the Island, with two logged sites in each of three recovery-time classes: 10, 30, and 50 years after logging. Within each study site, 12 0.1-ha plots were randomly established, and a series of forest attributes measured in each plot. Our results revealed that local logging intensity and soil attributes have stronger influence on forest-structural recovery than do site attributes such as local topography or tree architecture. Furthermore, half a century of regeneration following logging is insufficient to permit full recovery of forest structure. We conclude that logged forests on Kolombangara and possibly across the Solomon Islands may not fully recover structurally before the next logging cycle, in the absence of a policy on re-entry harvesting. The development of such a policy coupled with robust forest-management measures is pivotal to facilitating sustainable logging while supporting biodiversity conservation in the Solomon Islands. This may be the last best hope for saving lowland forests and their biodiversity on this unique tropical archipelago
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