See evidence of evolution

The competition between two species of sparrow in the Galapagos Islands has made a species' beak smaller, helping them find food more easily. Scientists have witnessed this change.

The large land-dwelling species (above) has competed with the average land-dwelling species to eat large seeds, making the average species tend to evolve into smaller beaks (below).(Photo: Nature)

In a recent article in Science, Peter Grant and Rosemary Grant, both biologists at Princeton University, New Jersey state (USA) have described the competition between average ground finches ( Geospiza fortis ) and species. Large land sparrow ( Geospiza magnirostris ).

G.fortis's average ground- dwelling creature was cornered and had to evolve into a smaller beak when a competitor appeared (the large sparrow Geospiza magnirostris , flew to the island more than 20 years ago) and conditions Recent severe drought.

"It happens very quickly," Peter Grant said. In fact, it happens in a single generation of birds, Grant said.

The evolution began when a few large sparrows came to settle on the island during an unusually wet El Nino in 1982.

Since then, this large species of G. magnirostris has eaten most of the large spiny seeds of vines on the island and gradually forced the average species to depend on smaller seeds of other plants.

As a result, G. fortis with a smaller beak does not compete with large species, and often does not raise their own. This forces some children to develop towards reducing their feeding tools.

But the real problem occurred in the middle of 2004-2004, when severe droughts on the island occurred and all kinds of seeds were scarce.

"Most large beak birds before drought have disappeared , " Grant said. This includes the majority of the new species to G. magnirostris and the G. fortis species that still hold the large beak.

"This is a classic example of rapid evolution," David Skelly, an ecologist and evolutionist at Yale University, commented on the situation.

Usually evolution is considered to be slow in large animals like fish, birds, reptiles and animals. The size of the mine changed for several decades seems to be too fast. Therefore, the Galapagos sparrow is considered to be an extremely fast evolving case caused by the harsh environment.

"Now it seems that Grant's work has shown a trend that can be very popular," Skelly said.

Medium land sparrow - Geospiza fortis (Photo: oursci.org)

Large land sparrow - Geospiza magnirostris (Photo: cahlander)

T. An