- Migratory Birds’ New Climate Change Strategy: Stay Home
- Fossil Turtle Had Extra-Thick Shell to Fend Off World’s Largest Snake
- Russian Physicists Synthesize New Superheavy Element 117
Posted: 06 Apr 2010 02:42 PM PDT
Birds may have an unexpected strategy for adapting to climate change. In addition to migrating at different times to newly hospitable locales, they may also shorten their migrations, expending energy on breeding and eating rather than flying.
"There's lots of data on bird arrival and bird breeding times, and that gives the impression that these are the most important phenomena," said zoologist Francisco Pulido of the Complutense University of Madrid. The basic impulse to migrate is likely just as important, "but it's been much more difficult to show, and so it hasn't been appreciated," he said.
Pulido and Max Planck Institute ornithologist Peter Berthold describe patterns found in 13 years of data from a southern German population of blackcaps, a common migratory songbird, in a study published April 5 in the Proceedings of the National Academy of Sciences.
As temperatures in central Europe have risen, blackcaps have arrived earlier at summertime breeding areas and departed later for their winter homes. Some researchers have predicted blackcaps would also migrate over ever-shorter distances, and in some cases stop altogether, allowing them to save energy and concentrate on finding food and mates. But this hadn't been tested.
To gauge the birds' migratory energies, Pulido and Berthold removed a few hundred blackcaps from the local population each summer. As captive birds are restless during the time they would typically be migrating, the researchers used them to measure the duration of wild migrations. These dropped slowly but steadily between 1988 and 2001, in keeping with predictions.
(Most of the captured birds were released at the end of each season, eventually catching up to their compatriots.)
In a second part of the study, Pulido and Berthold bred the most sedentary blackcaps. They wanted to accelerate the natural trend, seeing in a few years what would normally take decades. From this, they extrapolated that some blackcap populations could stop migrating altogether within 40 to 50 years. Other birds may do the same.
The next step in the research is connecting changes in migratory impulse to other adapations. Pulido speculates that shorter distances facilitate earlier arrivals, which in turn alter patterns of reproductive development.
However, shorter distances may only be an option for some species. Blackcap migration spans a relatively modest 1,000 miles, and sometimes less. For birds that travel thousands of miles, with no hospitable territory between their destinations, there may be no middle ground.
Blackcaps are also quite common. Species with smaller populations may be more vulnerable to weather extremes that become more common with warming, said Pulido.
"Adaptation requires a large population. Otherwise they'll go extinct," he said.
Image: Ignacio García/Flickr
Citation: "Current selection for lower migratory activity will drive the evolution of residency in a migratory bird population." By Francisco Pulido and Peter Berthold. Proceedings of the National Academy of Sciences, Vol. 107 No. 14, April 5, 2010.
Posted: 06 Apr 2010 02:22 PM PDT
A new fossil turtle species discovered in a Colombian coal mine had a shell as thick as a 400-page book, which may have protected it from crocodiles and the world's biggest known snake.
Scientists from the Smithsonian Tropical Research Institute and the Florida Museum of Natural History uncovered the Cerrejón coal mine. The 60-million-year-old fossilized shell found there was almost 1.5 inches thick and over 3 feet across. The scientists named the species Cerrejonemys wayuunaiki after the language of the local Wayuu people.
The giant snake that lived alongside this is called the Titanoboa cerrejonensis. Fossils of the snake, also discovered in Colombian coal mines in the same area as the turtle, show that it grew to be between 40 and 50 feet long. The longest known living snake species, Python reticulatus, has been measured at 29 feet long.
"The fossils from Cerrejón provide a snapshot of the first modern rainforest in South America — after the big Cretaceous extinctions and before the Andes rose, modern river basins formed and the Panama land bridge connected North and South America," Carlos Jarmillo, staff scientist at the Smithsonian who studies the plants from Cerrejón, said in a press release April 5.
Two more new fossil turtle species have turned up in the mines and will be described by Edwin Cadena of North Carolina State University, first author of the C. wayuunaiki paper publishedin the Journal of Vertebrate Paleontology.
"I hope this will give us an even better understanding of turtle diversity in the region and some important clues about the environment where they lived," Cadena said in the press release.
Images: 1) Edwin Cadena. 2)
Citation: Cadena, Edwin A., and Jonathan I. Bloch and Carlos A. Jaramillo. "New Podocnemidid Turtle (Testudines: Pleurodira) from the Middle-Upper Paleocene of South America." Journal of Vertebrate Paleontology 30.2 (2010): 367-382
Posted: 06 Apr 2010 10:36 AM PDT
Physicists have reported synthesizing element number 117, the latest in the quest to create artificial "superheavy" elements in the laboratory. A paper describing the discovery has been accepted for publication in Physical Review Letters.
A team led by Yuri Oganessian of the Joint Institute for Nuclear Research in Dubna, Russia, reports smashing together calcium-48 — an isotope with 20 protons and 28 neutrons — with berkelium-249, which has 97 protons and 152 neutrons. The collision spit out neutrons to create two isotopes of an element with 117 protons, one with 176 neutrons and the other with 177.
"These are very, very interesting results," says Witold Nazarewicz, a theorist at Oak Ridge National Laboratory in Tennessee. "This was carefully planned, and it would have been very difficult to synthesize this element without the berkelium target."
The new element, which has yet to be named, slips into a place on the periodic table between elements 116 and 118, both of which have already been discovered. Such superheavy elements are usually very radioactive and decay away almost instantly. But many researchers think it is possible that even heavier elements may occupy an "island of stability" in which superheavy atoms stick around for a while.
The new work supports that view. Analyses of the radioactive decay of the new element, Oganessian's team writes in the new paper, "represent an experimental verification for the existence of the predicted 'Island of Stability' for super-heavy elements."
Images: 1) Yuri Oganessian walks from the Joint Institute for Nuclear Research in Dubna, Russia, around 1989 with Ron Lougheed (left) and Ken Moody (right) of Lawrence Livermore National Laboratory, with whom he has collaborated on previous research into superheavy elements./LLNL.
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