Σάββατο 23 Νοεμβρίου 2013

ScienceDaily: Top Environment News

ScienceDaily: Top Environment News


Biodiversity higher in the tropics, but species more likely to arise at higher latitudes

Posted: 22 Nov 2013 10:24 AM PST

A study of 2300 species of mammals and 6700 species of birds helps explain why there are more species in the tropics than at higher latitudes. Researchers found that while the tropics harbor more species, the number of subspecies increases in the harsher environments typical of higher latitudes. The results suggest that the latitudinal diversity gradient may be due higher species turnover -- speciation counterbalanced by extinction -- towards the poles than near the equator.

Powerful tool for genetic engineering

Posted: 22 Nov 2013 08:27 AM PST

Viruses cannot only cause illnesses in humans, they also infect bacteria. Those protect themselves with a kind of "immune system" which -- simply put -- consists of specific sequences in the genetic material of the bacteria and a suitable enzyme. Scientists have now shown that the dual-RNA guided enzyme Cas9 which is involved in the process has developed independently in various strains of bacteria.

Pre-industrial rise in greenhouse gases had natural and anthropogenic causes

Posted: 22 Nov 2013 07:39 AM PST

For years scientists have intensely argued over whether increases of potent methane gas concentrations in the atmosphere -- from about 5,000 years ago to the start of the industrial revolution -- were triggered by natural causes or human activities. A new study suggests the increase in methane likely was caused by both. A new study, published Friday in the journal Science, suggests the increase in methane likely was caused by both.

Sea level rise forecasts helped by insights into glacier melting

Posted: 22 Nov 2013 07:38 AM PST

Predictions of sea level rise could become more accurate, thanks to new insight into how glacier movement is affected by melting ice in summer.

Expert assessment: Sea-level rise could exceed one meter in this century

Posted: 22 Nov 2013 07:38 AM PST

Sea-level rise in this century is likely to be 70-120 centimeters by 2100 if greenhouse-gas emissions are not mitigated, a broad assessment of the most active scientific publishers on that topic has revealed. The 90 experts participating in the survey anticipate a median sea-level rise of 200-300 centimeters by the year 2300 for a scenario with unmitigated emissions.

Smaller islands host shorter food chains

Posted: 22 Nov 2013 05:45 AM PST

That smaller islands will typically sustain fewer species than large ones is a widespread pattern in nature. Now a team of researchers shows that smaller area will mean not only fewer species, but also shorter food chains. This implies that plant and animal communities on small islands may work differently from those on large ones.

Archaeologists discover largest, oldest wine cellar in Near East: 3,700 year-old store room held 2,000 liters of strong, sweet wine

Posted: 22 Nov 2013 05:45 AM PST

Archaeologists have unearthed what may be the oldest -- and largest -- ancient wine cellar in the Near East, containing 40 jars, each of which would have held 50 liters of strong, sweet wine.

Colossal new predatory dino terrorized early tyrannosaurs

Posted: 22 Nov 2013 05:42 AM PST

A new species of carnivorous dinosaur – one of the three largest ever discovered in North America – lived alongside and competed with small-bodied tyrannosaurs 98 million years ago. Siats meekerorum, (pronounced see-atch) was the apex predator of its time.

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