Feeding birds can change their evolutionary future

Posted By: Staff
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Washington, December 4 (ANI): A new research has suggested that feeding birds can have profound effects on their evolutionary future, and those changes can be seen in the very near term.

The research showed that what was once a single population of birds known as blackcaps has been split into two reproductively isolated groups in fewer than 30 generations, despite the fact that they continue to breed side by side in the very same forests.

The 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 800 kilometers or more, according to the researchers.

"Our study documents the profound impact of human activities on the evolutionary trajectories of species," said Martin Schaefer of the University of Freiburg.

"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," he added.

The split that the researchers observed followed the recent establishment of a migratory divide between southwest- and northwest-migrating blackcap populations in Central Europe after humans began offering food to them in the winter. he two groups began to follow distinct migratory routes-wintering in Spain and the United Kingdom-and faced distinct selective pressures.

Under that pressure, the two groups have since become locally adapted ecotypes.

Ecotypes represent the initial step of differentiation among populations of the same species. If ecotypes continue down that path, they can ultimately become separate species

"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," he added.

They also have longer, narrower bills that are less equipped for eating large fruits like olives during the winter.

The findings speak to the long-standing debate about whether geographic separation is necessary for speciation to occur.

In particular, it had been contentious whether selection could act strongly and consistently enough in sympatry to separate a united gene pool.

"Our results now show that the initial steps of speciation can occur very quickly in a highly mobile, migratory bird," because divergent selection during the overwintering phase leads to the evolution of reproductive isolation, according to Schaefer. (ANI)

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