14 research outputs found
Biodiversity conservation: history, protected areas and hotspots
Angola is a large country of great physiographic, climatic and habitat
diversity, with a corresponding richness in animal and plant species. Legally protected
areas (National Parks and Game Reserves) were established from the 1930s
and occupied 6% of the countryâs terrestrial area at the time of independence in
1975. As a consequence of an extended war, the Protected Areas were exposed to
serious neglect, poaching and land invasions. Many habitats of biogeographic
importance, and many rare and endemic species came under threat. The recently
strengthened administration gives cause for optimism that a new era for biodiversity
conservation is at hand. The Protected Areas system was greatly expanded in 2011,
and increasing resources are being made available towards achieving management
effectivenessinfo:eu-repo/semantics/publishedVersio
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transientâs position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
The effects of old and recent migration waves in the distribution of HBB*S globin gene haplotypes
Abstract Sickle cell hemoglobin is the result of a mutation at the sixth amino acid position of the beta (β) globin chain. The HBB*S gene is in linkage disequilibrium with five main haplotypes in the β-globin-like gene cluster named according to their ethnic and geographic origins: Bantu (CAR), Benin (BEN), Senegal (SEN), Cameroon (CAM) and Arabian-Indian (ARAB). These haplotypes demonstrated that the sickle cell mutation arose independently at least five times in human history. The distribution of βS haplotypes among Brazilian populations showed a predominance of the CAR haplotype. American populations were clustered in two groups defined by CAR or BEN haplotype frequencies. This scenario is compatible with historical records about the slave trade in the Americas. When all world populations where the sickle cell gene occurs were analyzed, three clusters were disclosed based on CAR, BEN or ARAB haplotype predominance. These patterns may change in the next decades due to recent migrations waves. Since these haplotypes show different clinical characteristics, these recent migrations events raise the necessity to develop optimized public health programs for sickle cell disease screening and management
Early phases of a successful invasion: mitochondrial phylogeography of the common genet (Genetta genetta) within the Mediterranean Basin
The Mediterranean Basin, connected by cultural exchanges since prehistoric times, provides an outstanding framework to study species translo- cations. We address here the early phases of the successful invasion of the common genet (Genetta genetta), a small carnivoran supposedly introduced from Africa to Europe during historical times, by assessing mitochondrial nucleotide variability in 134 individuals from its native and invasive ranges. We identify four lineages within the native species range [northern Algeria, Peninsular Arabia, southern Africa and western Africa + Maghreb (including northern Algeria)], in contradiction with morpho- logical taxonomy. We propose that the co- occurrence in Maghreb of two divergent lineages (autochthonous and western African) is due to secondary contact through intermittent permeability of the Saharan belt during the Plio-Pleistocene. Estimates of coalescence time and genetic diversity, in concert with other available evidences in the literature, indicate that the origin of European populations of common genets is in Maghreb, possibly restricted to northern Algeria. The autoch- thonous mitochondrial lineage of Maghreb was the only contributor to the European pool, suggesting that translocations were associated to a cultural constraint such as a local use of the species, which might have artificially excluded the western African lineage. Haplotype network and nested clade analysis (NCA) provide evidence for independent events of introductions throughout Spain (Andalucia, CatalunË a, and the Balearic Isl.)âand, to a lesser extent, Portugalâacting as a âtranslocation hotspotâ. Due to the reduced number of northern Algerian individuals belonging to the autochthonous mitochondrial line- age of Maghreb, it remains impossible to test hypotheses of historical translocations, although a main contribution of the Moors is likely. Our demographic analyses support a scenario of very recent introduction of a reduced number of individ- uals in Europe followed by rapid population expansion. We suggest that an exceptional combi- nation of factors including multiple translocations, human-driven propagation across natural barriers, and natural processes of colonization allowed by a wide ecological tolerance, promoted the successful spread of the common genet into EuropePeer reviewe