The Tasmanian Wedge-Tailed Eagle
was long assumed to have diverged from Australia’s mainland species after being
isolated on Tasmania when water levels rose over 15,000 feet at the end of the
Ice Age. However, recent evidence points toward a much more recent
split—perhaps in the last few hundred years. Scientists have extensively tested
the DNA of mainland birds and the Tasmanian subspecies, and have found that the
genetic variation is actually quite acute, pointing toward a relatively short
isolation period. This means that the bird was not trapped on the island at the
end of the Ice Age at all—all it did was simply fly across the Bass Straight.
So what about the distinct visual
differences among mainland and Tasmanian eagles? We can blame the island for that. It is likely that only
a small, specific group of birds flew to Tasmania, where their phenotypically
distinct characteristics were selected for and perpetuated.
The discovery will help scientists
come up with a better plan to fight the loss of the endangered bird, whose role
as a top predator is vastly important now that the thylacine is extinct, and
the Tasmanian devils are shrinking in population.
An immature wedge-tailed
eagle on Tasmania
Source: http://bit.ly/1AmgzIi
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