Humans Altering the Evolution of Animals

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Taken from Upstream 2009.

Humans Altering Evolution of Animals

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DeliaTheArtist
“Our study documents the profound impact of human activities on the evolutionary trajectories of species,” said researcher Martin Schaefer, an evolutionary biologist at the University of Freiburg in Germany. “It shows that we are influencing the fate not only of rare and endangered species, but also of the common ones that surround our daily lives.”

Over the course of three-and-a-half years, the scientists followed birds known as blackcaps (Sylvia atricapilla) in Central Europe after humans began offering food to them. A recent divide has sprung up, with two groups following distinct migration routes in the winter — one southwest in Spain, the other northwest in the United Kingdom.

“The new northwest migratory route is shorter, and those birds feed on food provided by humans instead of fruits as the birds that migrate southwest do,” Schaefer said. “As a consequence, birds migrating northwest have rounder wings, which provide better maneuverability but make them less suited for long-distance migration.” They also have longer, narrower bills that are less equipped for eating large fruits like olives during the winter.

This discovery, detailed online Dec. 3 in the journal Current Biology, speaks to a long-standing debate in evolution about whether geographic separation is necessary for new species to develop. By now, the level of reproductive isolation between these populations, which live together for part of the year, is now stronger than that of other blackcaps that are always separated from one another by distances of 500 miles (800 km) or more.

“This is a nice example of the speed of evolution,” Schaefer said. “It is something that we can see with our own eyes if we only look closely enough. It doesn’t have to take millions of years.”

If such isolation and differentiation continues, they can ultimately become separate species.

“The initial steps in speciation — that is, the evolution of reproductive isolation, have rarely been studied,” Schaefer said. “This is because speciation is necessarily a historic process, and it is extremely difficult to analyze the selective pressures that lead to speciation in hindsight. Here, we can witness those initial steps.”

http://www.livescience.com/animals/091203-birdfeeding-evolution.html

Humans Altering Evolution of Animals

Image
DeliaTheArtist

“Our study documents the profound impact of human activities on the evolutionary trajectories of species,” said researcher Martin Schaefer, an evolutionary biologist at the University of Freiburg in Germany. “It shows that we are influencing the fate not only of rare and endangered species, but also of the common ones that surround our daily lives.”

Over the course of three-and-a-half years, the scientists followed birds known as blackcaps (Sylvia atricapilla) in Central Europe after humans began offering food to them. A recent divide has sprung up, with two groups following distinct migration routes in the winter — one southwest in Spain, the other northwest in the United Kingdom.

“The new northwest migratory route is shorter, and those birds feed on food provided by humans instead of fruits as the birds that migrate southwest do,” Schaefer said. “As a consequence, birds migrating northwest have rounder wings, which provide better maneuverability but make them less suited for long-distance migration.” They also have longer, narrower bills that are less equipped for eating large fruits like olives during the winter.

This discovery, detailed online Dec. 3 in the journal Current Biology, speaks to a long-standing debate in evolution about whether geographic separation is necessary for new species to develop. By now, the level of reproductive isolation between these populations, which live together for part of the year, is now stronger than that of other blackcaps that are always separated from one another by distances of 500 miles (800 km) or more.

“This is a nice example of the speed of evolution,” Schaefer said. “It is something that we can see with our own eyes if we only look closely enough. It doesn’t have to take millions of years.”

If such isolation and differentiation continues, they can ultimately become separate species.

“The initial steps in speciation — that is, the evolution of reproductive isolation, have rarely been studied,” Schaefer said. “This is because speciation is necessarily a historic process, and it is extremely difficult to analyze the selective pressures that lead to speciation in hindsight. Here, we can witness those initial steps.”

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