By Michael Torrice ScienceNOW Daily News
3 December 2009
During the winter, British bird-lovers lay out suet rolled with seeds and oats for birds landing in their chilly, barren yards. They believe that these handouts help the birds through winter, but scientists have now discovered that the practice may be splitting a species in two.
In the past 50 years, a migratory schism has appeared among central European blackcaps (Sylvia atricapilla). Native to southern Germany and Austria, the small, grayish songbirds used to fly southwest together to Spain to bask in the Mediterranean weather and dine on fruits such as olives. But in the 1960s, bird watchers started noticing some blackcaps wintering in the United Kingdom. These birds had split from their companions, headed northwest, and begun living off the feed left out by generous bird-lovers. Now, roughly 30 generations later, about 10% of blackcaps migrate to the United Kingdom in the winter instead of to Spain.
A recent study showed that this new winter destination has led blackcaps to breed mainly with their migratory companions. The United Kingdom is closer to blackcap breeding grounds in central Europe than is Spain, so the northwest-migrating birds return home 10 days earlier and start mating among themselves.
Evolutionary biologist H. Martin Schaefer of the University of Freiburg in Germany and colleagues wondered whether the breeding separation had evolutionary consequences. So the scientists caught blackcaps when the birds returned to Germany in the spring and sequenced short stretches of their genomes called microsatellites. The genetic difference between the two groups is small but significant--on a scale from zero (totally similar) to one (separate species), they scored a 0.008. Despite this slight difference, the researchers could still use the genetic data to accurately assign 85% of the birds to the correct migratory group.
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Last edited on Fri Dec 4th, 2009 12:35 pm by sydneyst
Scientists have published the first comprehensive description of a 4.4-million-year-old skeleton of Ardipithecus ramidus. Known as Ardi, the specimen is the earliest known skeleton from the human branch of the primate family tree.
Ardi was an adult female that probably stood four feet tall and weighed about 120 pounds. It walked upright but lacked the archlike foot structure and efficient gait of later hominids, and its long arms, long hands and short legs allowed for agile tree-climbing. The skeleton was discovered along the Awash River in Ethiopia, near where the Lucy skeleton was found in 1974.(Source: Science)
Last edited on Wed Oct 14th, 2009 09:07 pm by sydneyst