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News Article
Site: http://phys.org/biology-news/

Some species of plants are capable of colonising new habitats thanks to birds that transport their seeds in their plumage or digestive tract. Until recently, it was known that birds could do this over short distances, but a new study shows that they are also capable of dispersing them over more than 300 kilometres. For researchers, this function could be key in the face of climate change, allowing the survival of many species. Birds can act as dispersers of seeds and other propagules —buds, bulbs, tubers or spores— over short distances which, in many cases, do not exceed a kilometre and a half. However, it had not been demonstrated whether they were capable of doing so over longer distances. A team led by scientists at the Doñana Biological Station-CSIC (Spanish Council for Scientific Research) in Seville (Spain) confirmed this hypothesis due to the seeds found in the digestive tract of various species of birds hunted in the Canaries by Eleonora's falcons (Falco eleonorae) during their migration towards Africa. "This mechanism of long-distance dispersion had not been confirmed until now, mainly due to the difficulty involved in sampling propagules transported by birds during their migratory flight. We were able to analyse it thanks to the hunting behaviour of Eleonora's falcons," Duarte Viana, researcher in the Doñana Biological Station and co-author of the study, explained to SINC. The data, published in the journal Proceedings of the Royal Society B, reveal for the first time that there are species that may be excellent dispersers of propagules over long distances of more than 300 km. These birds were flying over the sea in an area located between the Canaries and Africa, and scientists found in them seeds that belonged to a plant that was not native to the Canary Islands, which demonstrates that they are capable of promoting colonisation of distant and remote areas. In total, researchers sampled 408 specimens of 21 species. Five birds from three different species stored 45 seeds inside them: the European pied flycatcher (Ficedula hypoleuca), the common redstart (Phoenicurus phoenicurus) and the common quail (Coturnix coturnix). The first two transported seeds of fleshy fruits (two species of the Rhamnus genus), while the common quail transported up to three different species (Rubus, Genisteae and Persicaria).. "The best dispersers would be frugivorous birds, which eat fruit; granivorous birds, which eat seeds, such as the quail; and water birds, many of which eat the sediment of ponds. We could be talking about thousands of species of birds around the world, many of which are migratory," said Viana. According to researchers, faced with a situation of global change, long-distance dispersers will allow many species of plants and organisms to reach new habitats that offer them optimal conditions for their survival. The seeds transported by migratory birds are defecated and deposited in the place where the birds arrive. If the new habitat is favourable to germination and the subsequent establishment of a viable population, the species of plant dispersed may successfully colonise this area, grow and reproduce. The study was focused on three islands to the northeast of the archipelago of the Canaries: Alegranza -from which a large part of the samples were obtained-, Montaña Clara and Roque del Este, places where Eleonora's falcon nests and towards which the trade winds usually drag the migratory birds that go from Europe to Africa. Here they are hunted, particularly in October, when there is large-scale migration. After examining the stomach and intestine contents of the prey stored in the falcon nests, the experts demonstrate that most of the species to which the seeds belong grow more than 100 or 200km from the islands studies, and one of them, Persicaria, is not even a Canary Island. "In the particular case of Alegranza, the likelihood of colonisation is slim since this islet has an extremely arid climate, which is unsuitable for the life of most plant species. However, other islands of the Canary archipelago may have been colonised through seeds that come from further afield, continental Africa or, more likely, the Iberian Peninsula," concluded Viana. More information: Duarte S. Viana et al. Overseas seed dispersal by migratory birds, Proceedings of the Royal Society B: Biological Sciences (2016). DOI: 10.1098/rspb.2015.2406


News Article
Site: http://phys.org/biology-news/

Rallus aquaticus skull (above) and Rallus "minutus" (below). Scale: 2 cm. / Alcover et al. When Charles Darwin visited the Azores islands in the 19th Century, the birds he observed were familiar to him. However, if he had travelled there 500 years before, he would have found an ornithofauna as particular as that of the Galápagos. The recent discovery in these Portuguese islands and in Madeira of five extinct species of rail, which lost the ability to fly due to having evolved on islands, confirms how fragile they are in the face of changes to their habitat like the ones that must have occurred after the first visits by humans over 500 years ago. In September 1826, the British naturalist Charles Darwin visited the Azores archipelago during the HMS Beagle's return voyage to the United Kingdom after more than four years travelling the world. In his diary he only mentions the existence of starlings, wagtails, finches and blackbirds; however, on the islands also lay the remains of other birds which populated the islands a few centuries before his visit. A new study, published in Zootaxa, now highlights the discovery of five extinct rail species, two in Madeira and three in the Azores. "The species of birds very probably disappeared following the arrival of humans and the animals that came with them, like mice, rats and cats," told Josep Antoni Alcover Paleontological exploration by Spanish, German and Portuguese researchers has made it possible to "discover new species of birds that very probably disappeared following the arrival of humans and the animals that came with them, like mice, rats and cats," SINC was told by Josep Antoni Alcover, a CSIC researcher working at the Mediterranean Institute for Advanced Studies (IMEDEA-CSIC/UIB) and co-author of the paper. The new species are: the Madeira rail (Rallus lowei), a flightless species with a very stout body; the Porto Santo rail (Rallus adolfocaesaris), graceful and probably not a very able flier; the São Miguel rail (Rallus carvaoensis), quite small, stout, flightless and with a somewhat curved beak; the Pico rail (Rallus montivagorum), larger than the São Miguel rail (but smaller than the continental species), graceful and with reduced flying capability; and the São Jorge rail (Rallus "minutus"), diminutive, relatively stout, with short legs, flightless and which does not have a definitive scientific name. According to dating obtained from the bones of these birds, or from those of other species found which were associated to them, these five extinct species lived until fairly recently, especially the Azores rails. "At least one of these species survived until the 15th Century, so we are looking at a very recent extinction process," stresses Alcover. According to the scientist, in Madeira the extinction may have been related to a possible visit by the Vikings (whether it was a colonisation is still not verified), who could have transported mice to the island. These would have brought about the disappearance of rails and other birds. "The bone remains of native bird species which are now appearing show that if Darwin had been able to study the fossils hidden on these islands, or if he had visited 500 years earlier, he would have found a much more singular ornithofauna, with many indigenous bird species, like that which was found on the Galápagos islands," Alcover highlights. Today, there are only 13 living rail species of the Rallus genus. "This is because other species, which only lived on islands, have disappeared recently," the expert clarifies. Two or three thousand insular rail species (rallids) are thought to have lived in the Pacific. In the Atlantic, only on the most remote islands, such as Tristan da Cunha and Gough, are there surviving indigenous rail species today; however, in the Antilles, Bermuda and on the islands of Ascension and Saint Helena, extinct species have been found. The extinct birds found on the islands of Macaronesia "were smaller in size than today's continental rails, such as the water rail (Rallus aquaticus), from which they very probably originate," says Alcover. Fossils uncovered also make it possible to verify that all these species had a reduced flying capability. "Some were completely incapable of regular flight," the researcher reveals. While on continents, rails live near water, on islands, they occupy more terrestrial habitats. The reason for this is that in order to live on islands, they evolve differently, to the point where they become indigenous insular species. This evolution implies changes in their size and body proportions and a reduction or complete loss of their ability to fly; this is why they tend to walk. "For that reason, the rails that reach islands and evolve on them lose their dispersive capacity: they cannot leave the islands and they are trapped in limited insular territories, which is why we observe an extremely reduced distribution area," the scientist explains. "The history of insular rails is an intense story of evolution, and frequently, extinction," Alcover highlights This circumstance also makes them very prone to extinction when there are changes to the islands' ecology (for example, when they are colonised by humans). "The history of insular rails is an intense story of evolution, and frequently, extinction," Alcover highlights. The tip of the iceberg of diversity The fossil remains surfacing on the Madeira and Azores archipelagos represent one part of all the diversity of animals that used to inhabit these islands, and are now beginning to be discovered. In addition to the five rail species the paper describes, there are other species, for example two indigenous species of scops owl. "This is only the tip of the iceberg of what is to come in terms of knowledge about the ornithological fauna native to these islands", according to the authors. "The existence in the past of indigenous species of scops owls and rails points to the great magnitude of the devastation birds suffered on Atlantic islands after the arrival of humans and the fauna that came with them," the scientists conclude. Explore further: An extinct species of scops owl has been discovered in Madeira Five new extinct species of rails (Aves: Gruiformes: Rallidae) from the Macaronesian Islands (North Atlantic Ocean)


News Article
Site: http://phys.org/space-news/

For decades, astronomers have known there is a dense, compact source at the center of RCW 103, the remains of a supernova explosion located about 9,000 light years from Earth. This composite image shows RCW 103 and its central source, known officially as 1E 161348-5055 (1E 1613, for short), in three bands of X-ray light detected by Chandra. In this image, the lowest energy X-rays from Chandra are red, the medium band is green, and the highest energy X-rays are blue. The bright blue X-ray source in the middle of RCW 103 is 1E 1613. The X-ray data have been combined with an optical image from the Digitized Sky Survey. Observers had previously agreed that 1E 1613 is a neutron star, an extremely dense star created by the supernova that produced RCW 103. However, the regular variation in the X-ray brightness of the source, with a period of about six and a half hours, presented a puzzle. All proposed models had problems explaining this slow periodicity, but the main ideas were of either a spinning neutron star that is rotating extremely slowly because of an unexplained slow-down mechanism, or a faster-spinning neutron star that is in orbit with a normal star in a binary system. On June 22, 2016, an instrument aboard NASA's Swift telescope captured the release of a short burst of X-rays from 1E 1613. The Swift detection caught astronomers' attention because the source exhibited intense, extremely rapid fluctuations on a time scale of milliseconds, similar to other known magnetars. These exotic objects possess the most powerful magnetic fields in the Universe -trillions of times that observed on the Sun - and can erupt with enormous amounts of energy. Seeking to investigate further, a team of astronomers led by Nanda Rea of the University of Amsterdam quickly asked two other orbiting telescopes - NASA's Chandra X-ray Observatory and Nuclear Spectroscopic Telescope Array, or NuSTAR - to follow up with observations. New data from this trio of high-energy telescopes, and archival data from Chandra, Swift and ESA's XMM-Newton confirmed that 1E 1613 has the properties of a magnetar, making it only the 30th known. These properties include the relative amounts of X-rays produced at different energies and the way the neutron star cooled after the 2016 burst and another burst seen in 1999. The binary explanation is considered unlikely because the new data show that the strength of the periodic variation in X-rays changes dramatically both with the energy of the X-rays and with time. However, this behavior is typical for magnetars. But the mystery of the slow spin remained. The source is rotating once every 24,000 seconds (6.67 hours), much slower than the slowest magnetars known until now, which spin around once every 10 seconds. This would make it the slowest spinning neutron star ever detected. Astronomers expect that a single neutron star will be spinning quickly after its birth in the supernova explosion and will then slow down over time as it loses energy. However, the researchers estimate that the magnetar within RCW 103 is about 2,000 years old, which is not enough time for the pulsar to slow down to a period of 24,000 seconds by conventional means. While it is still unclear why 1E 1613 is spinning so slowly, scientists do have some ideas. One leading scenario is that debris from the exploded star has fallen back onto magnetic field lines around the spinning neutron star, causing it to spin more slowly with time. Searches are currently being made for other very slowly spinning magnetars to study this idea in more detail. Another group, led by Antonino D'Aì at the National Institute of Astrophysics (INAF) in Palermo, Italy, monitored 1E 1613 in X-rays using Swift and in the near-infrared and visible light using the 2.2-meter telescope at the European Southern Observatory at La Silla, Chile, to search for any low-energy counterpart to the X-ray burst. They also conclude that 1E 1613 is a magnetar with a very slow spin period. A paper describing the findings of Rea's team appears in the September 2, 2016, issue of The Astrophysical Journal Letters and is available online. The authors of that paper are Nanda Rea (University of Amsterdam and IEEC-CSIC, Spain), A. Borghese (Univ. of Amsterdam), P. Esposito (Univ. of Amsterdam), F. Coti Zelati (Univ. of Amsterdam, INAF, Insubria), M. Bachetti (INAF), G. L. Israel (INAF), A. De Luca (INAF). A paper describing the findings of D'Aì's team has been accepted for publication by Monthly Notices of the Royal Astronomical Society and is also available online. NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington. NASA's Swift satellite was launched in November 2004 and is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland.


News Article | April 28, 2016
Site: http://phys.org/biology-news/

A new study led by ICTA-UAB (Universitat Autònoma de Barcelona) researcher Víctor Sarto and colleagues from the Institute of Advanced Chemistry of Catalonia (CSIC-IQAC) has described for the first time in two centuries of knowledge a case of evolutionary convergence in the order of butterflies (Lepidoptera), certainly representing an evolutionary breakthrough to what has been known about their sexual communication. The research has discovered important behavior and physiological changes in the mating process of the moth Paysandisia archon (Castniidae). This neotropical moth that reached Europe in 2001 from Argentina (also inhabiting Uruguay and Brasil) breaks the known sexual rules by behaving like a diurnal butterfly.


News Article
Site: http://phys.org/biology-news/

The turbot lives on the sea-bed, which means it has had to adapt to an environment of very little light and chillier waters. Credit: CSIC Communications Department The first vertebrate to be genetically sequenced in Spain, the Turbot (Scophthalmus maximus), has a much more highly developed sense of sight than other fish, since it has evolved in order to adapt itself to the lack of light on the sea bed. In addition, its genes show us that the levels of fat in its cellular membranes are far higher than in other species, so as to be able to withstand the low water temperatures in its habitat. The complete genome sequencing of this fish, carried out by scientists from the Spanish National Research Council (CSIC), the University of Santiago de Compostela, and Spain's National Centre for Genome Analysis in Barcelona have brought this and other conclusions to light. The work opens the way for further investigation, not only into the Turbot's resistance to different illnesses, but also to look more deeply into how other fish respond to these pathologies. The results, published in the magazine DNA Research, could be used in the future design of genetic selection programmes, or in possible vaccines. The flat-bodied Turbot, rhomboid-shaped, and with both eyes found on its left side, underwent a process of metamorphosis during its development, which is when it began to develop a body distribution which is atypical in flat fish. And it's because of this circumstance it lives on the sea-bed, which means it has had to adapt to an environment of very little light and chillier waters. "We have seen that many of the genes which are involved in sight, mainly those which carry pigment codes, and others involved in forming the crystalline, are repeated in this vertebrate with respect to other fish. This would indicate that they have evolved, refining their sense of sight to adapt to the low levels of light which surrounds them", says CSIC investigator, Antonio Figueras, from the Institute of Marine Investigation in Vigo. In order to tolerate these low temperatures, the Turbot has a number of genes related to fatty acids in the repeated cellular membranes, when compared with other organisms which live at higher temperatures. The lipid composition of these membranes is a key factor when it comes to withstanding cold. Scientists have managed to identify the most important genes involved in growth, sexual differentiation, and disease resistance, including which specific parts of the genome affect these production traits. "This information is essential to the development of more efficient genetic selection projects, with the aim of identifying the breeding fish with the best production traits", highlights Figueras. Spain is the number one producer of farmed turbot in Europe, with 99% of the total harvest produced in Galicia. According to a report by The Business Association of Marine Aquaculture Producers (APROMAR), European Turbot production reached 11,000 tonnes in 2014, 38% up on 2013. In the same year, the estimated value of the catch across Europe was €75.6m. According to Paulino Martínez, a researcher at the University of Santiago de Compostela, although present day turbot farming is well established, the main problems fish farmers face are related to the species' susceptibility to a range of bacterial, viral, or parasitic diseases and illnesses. As yet, no vaccines or effective treatment exist for many of these pathologies. Another of the challenges facing the sector is how to shorten the time required for the fish to reach a marketable size. "This could be improved by selecting those genes which are involved in growth and sexual differentiation, given that females show far better growth rates compared with males", adds Martínez. Explore further: Blind cave fish may provide insight on eye disease and other human health issues

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